==================================
Reading and Writing Config Files
==================================
----------------------------------------
ConfigObj 4 Introduction and Reference
----------------------------------------
:Authors: Michael Foord, Nicola Larosa
:Version: ConfigObj 4.5.2
:Date: 2008/02/24
:Homepage: `ConfigObj Homepage`_
:Sourceforge: Sourceforge_
:Development: `SVN Repository`_
:License: `BSD License`_
:Support: `Mailing List`_
.. _Mailing List: http://lists.sourceforge.net/lists/listinfo/configobj-develop
.. _SVN Repository: http://svn.pythonutils.python-hosting.com
.. meta::
:description: ConfigObj - a Python module for easy reading and writing of
config files.
:keywords: python, script, module, config, configuration, data, persistence,
developer, configparser
.. contents:: ConfigObj Manual
.. sectnum::
Introduction
============
**ConfigObj** is a simple but powerful config file reader and writer: an *ini
file round tripper*. Its main feature is that it is very easy to use, with a
straightforward programmer's interface and a simple syntax for config files.
It has lots of other features though :
* Nested sections (subsections), to any level
* List values
* Multiple line values
* String interpolation (substitution)
* Integrated with a powerful validation system
- including automatic type checking/conversion
- repeated sections
- and allowing default values
* When writing out config files, ConfigObj preserves all comments and the order of members and sections
* Many useful methods and options for working with configuration files (like the 'reload' method)
* Full Unicode support
For support and bug reports please use the ConfigObj `Mailing List`_.
Downloading
===========
The current version is **4.5.2**, dated 24th February 2008. ConfigObj 4 is
now stable. We still expect to pick up a few bugs along the way though [#]_.
{sm;:-)}
You can get ConfigObj in the following ways :
Files
-----
* configobj.py_ from Voidspace
ConfigObj has no external dependencies. This file is sufficient to access
all the functionality except Validation_.
* configobj.zip_ from Voidspace
This also contains validate.py_ and `this document`_.
* The latest development version can be obtained from the `Subversion
Repository`_.
* validate.py_ from Voidspace
* You can also download *configobj.zip* from Sourceforge_
Documentation
-------------
*configobj.zip* also contains `this document`_.
* You can view `this document`_ online at the `ConfigObj Homepage`_.
Pythonutils
-----------
ConfigObj is also part of the Pythonutils_ set of modules. This contains
various other useful modules, and is required by many of the `Voidspace Python
Projects`_.
Development Version
-------------------
It is sometimes possible to get the latest *development version* of ConfigObj
from the `Subversion Repository `_.
.. _configobj.py: http://www.voidspace.org.uk/cgi-bin/voidspace/downman.py?file=configobj.py
.. _configobj.zip: http://www.voidspace.org.uk/cgi-bin/voidspace/downman.py?file=configobj-4.5.2.zip
.. _validate.py: http://www.voidspace.org.uk/cgi-bin/voidspace/downman.py?file=validate.py
.. _this document:
.. _configobj homepage: http://www.voidspace.org.uk/python/configobj.html
.. _Sourceforge: http://sourceforge.net/projects/configobj
.. _pythonutils: http://www.voidspace.org.uk/python/pythonutils.html
.. _Voidspace Python Projects: http://www.voidspace.org.uk/python/index.shtml
ConfigObj in the Real World
===========================
**ConfigObj** is widely used. Projects using it include:
* `Bazaar `_.
Bazaar is a Python distributed {acro;VCS;Version Control System}.
ConfigObj is used to read ``bazaar.conf`` and ``branches.conf``.
* `Turbogears `_
Turbogears is a web application framework.
* `Chandler `_
A Python and `wxPython `_
{acro;PIM;Personal Information Manager}, being developed by the
`OSAFoundation `_.
* `matplotlib `_
A 2D plotting library.
* `IPython `_
IPython is an enhanced interactive Python shell. IPython uses ConfigObj in a module called 'TConfig' that combines it with enthought `Traits `_: `tconfig `_.
* `Elisa - the Fluendo Mediacenter `_
Elisa is an open source cross-platform media center solution designed to be simple for people not particularly familiar with computers.
Getting Started
===============
The outstanding feature of using ConfigObj is simplicity. Most functions can be
performed with single line commands.
Reading a Config File
---------------------
The normal way to read a config file, is to give ConfigObj the filename :
.. raw:: html
{+coloring}
from configobj import ConfigObj
config = ConfigObj(filename)
{-coloring}
You can also pass the config file in as a list of lines, or a ``StringIO``
instance, so it doesn't matter where your config data comes from.
You can then access members of your config file as a dictionary. Subsections
will also be dictionaries.
.. raw:: html
{+coloring}
from configobj import ConfigObj
config = ConfigObj(filename)
#
value1 = config['keyword1']
value2 = config['keyword2']
#
section1 = config['section1']
value3 = section1['keyword3']
value4 = section1['keyword4']
#
# you could also write
value3 = config['section1']['keyword3']
value4 = config['section1']['keyword4']
{-coloring}
Writing a Config File
---------------------
Creating a new config file is just as easy as reading one. You can specify a
filename when you create the ConfigObj, or do it later [#]_.
If you *don't* set a filename, then the ``write`` method will return a list of
lines instead of writing to file. See the write_ method for more details.
Here we show creating an empty ConfigObj, setting a filename and some values,
and then writing to file :
.. raw:: html
{+coloring}
from configobj import ConfigObj
config = ConfigObj()
config.filename = filename
#
config['keyword1'] = value1
config['keyword2'] = value2
#
config['section1'] = {}
config['section1']['keyword3'] = value3
config['section1']['keyword4'] = value4
#
section2 = {
'keyword5': value5,
'keyword6': value6,
'sub-section': {
'keyword7': value7
}
}
config['section2'] = section2
#
config['section3'] = {}
config['section3']['keyword 8'] = [value8, value9, value10]
config['section3']['keyword 9'] = [value11, value12, value13]
#
config.write()
{-coloring}
.. caution::
Keywords and section names can only be strings [#]_. Attempting to set
anything else will raise a ``ValueError``.
Config Files
------------
The config files that ConfigObj will read and write are based on the 'INI'
format. This means it will read and write files created for ``ConfigParser``
[#]_.
Keywords and values are separated by an ``'='``, and section markers are
between square brackets. Keywords, values, and section names can be surrounded
by single or double quotes. Indentation is not significant, but can be
preserved.
Subsections are indicated by repeating the square brackets in the section
marker. You nest levels by using more brackets.
You can have list values by separating items with a comma, and values spanning
multiple lines by using triple quotes (single or double).
For full details on all these see `the config file format`_. Here's an example
to illustrate : ::
# This is the 'initial_comment'
# Which may be several lines
keyword1 = value1
'keyword 2' = 'value 2'
[ "section 1" ]
# This comment goes with keyword 3
keyword 3 = value 3
'keyword 4' = value4, value 5, 'value 6'
[[ sub-section ]] # an inline comment
# sub-section is inside "section 1"
'keyword 5' = 'value 7'
'keyword 6' = '''A multiline value,
that spans more than one line :-)
The line breaks are included in the value.'''
[[[ sub-sub-section ]]]
# sub-sub-section is *in* 'sub-section'
# which is in 'section 1'
'keyword 7' = 'value 8'
[section 2] # an inline comment
keyword8 = "value 9"
keyword9 = value10 # an inline comment
# The 'final_comment'
# Which also may be several lines
ConfigObj specifications
========================
.. raw:: html
{+coloring}
config = ConfigObj(infile=None, options=None, **keywargs)
{-coloring}
infile
------
You don't need to specify an infile. If you omit it, an empty ConfigObj will be
created. ``infile`` *can* be :
* Nothing. In which case the ``filename`` attribute of your ConfigObj will be
``None``. You can set a filename at any time.
* A filename. What happens if the file doesn't already exist is determined by
the options_ ``file_error`` and ``create_empty``. The filename will be
preserved as the ``filename`` attribute. This can be changed at any time.
* A list of lines. Any trailing newlines will be removed from the lines. The
``filename`` attribute of your ConfigObj will be ``None``.
* A ``StringIO`` instance or file object, or any object with a ``read`` method.
The ``filename`` attribute of your ConfigObj will be ``None`` [#]_.
* A dictionary. You can initialise a ConfigObj from a dictionary [#]_. The
``filename`` attribute of your ConfigObj will be ``None``. All keys must be
strings. In this case, the order of values and sections is arbitrary.
options
-------
There are various options that control the way ConfigObj behaves. They can be
passed in as a dictionary of options, or as keyword arguments. Explicit keyword
arguments override the dictionary.
All of the options are available as attributes after the config file has been
parsed.
ConfigObj has the following options (with the default values shown) :
* 'raise_errors': ``False``
When parsing, it is possible that the config file will be badly formed. The
default is to parse the whole file and raise a single error at the end. You
can set ``raise_errors = True`` to have errors raised immediately. See the
exceptions_ section for more details.
Altering this value after initial parsing has no effect.
* 'list_values': ``True``
If ``True`` (the default) then list values are possible. If ``False``, the
values are not parsed for lists.
If ``list_values = False`` then single line values are not quoted or
unquoted when reading and writing.
Changing this value affects whether single line values will be quoted or
not when writing.
* 'create_empty': ``False``
If this value is ``True`` and the file specified by ``infile`` doesn't
exist, ConfigObj will create an empty file. This can be a useful test that
the filename makes sense: an impossible filename will cause an error.
Altering this value after initial parsing has no effect.
* 'file_error': ``False``
If this value is ``True`` and the file specified by ``infile`` doesn't
exist, ConfigObj will raise an ``IOError``.
Altering this value after initial parsing has no effect.
* 'interpolation': ``True``
Whether string interpolation is switched on or not. It is on (``True``) by
default.
You can set this attribute to change whether string interpolation is done
when values are fetched. See the `String Interpolation`_ section for more details.
* 'configspec': ``None``
If you want to use the validation system, you supply a configspec. This is
effectively a type of config file that specifies a check for each member.
This check can be used to do type conversion as well as check that the
value is within your required parameters.
You provide a configspec in the same way as you do the initial file: a
filename, or list of lines, etc. See the validation_ section for full
details on how to use the system.
When parsed, every section has a ``configspec`` with a dictionary of
configspec checks for *that section*.
* 'stringify': ``True``
If you use the validation scheme, it can do type checking *and* conversion
for you. This means you may want to set members to integers, or other
non-string values.
If 'stringify' is set to ``True`` (default) then non-string values will
be converted to strings when you write the config file. The validation_
process converts values from strings to the required type.
If 'stringify' is set to ``False``, attempting to set a member to a
non-string value [#]_ will raise a ``TypeError`` (no type conversion is
done by validation).
* 'indent_type': ``' '``
Indentation is not significant; it can however be present in the input and
output config. Any combination of tabs and spaces may be used: the string
will be repeated for each level of indentation. Typical values are: ``''``
(no indentation), ``' '`` (indentation with four spaces, the default),
``'\t'`` (indentation with one tab).
If this option is not specified, and the ConfigObj is initialised with a
dictionary, the indentation used in the output is the default one, that is,
four spaces.
If this option is not specified, and the ConfigObj is initialised with a
list of lines or a file, the indentation used in the first indented line is
selected and used in all output lines. If no input line is indented, no
output line will be either.
If this option *is* specified, the option value is used in the output
config, overriding the type of indentation in the input config (if any).
* 'encoding': ``None``
By default **ConfigObj** does not decode the file/strings you pass it into
Unicode [#]_. If you want your config file as Unicode (keys and members)
you need to provide an encoding to decode the file with. This encoding will
also be used to encode the config file when writing.
You can change the encoding attribute at any time.
Any characters in your strings that can't be encoded with the specified
encoding will raise a ``UnicodeEncodeError``.
.. note::
``UTF16`` encoded files will automatically be detected and decoded,
even if ``encoding`` is ``None``.
This is because it is a 16-bit encoding, and ConfigObj will mangle it
(split characters on byte boundaries) if it parses it without decoding.
* 'default_encoding': ``None``
When using the ``write`` method, **ConfigObj** uses the ``encoding``
attribute to encode the Unicode strings. If any members (or keys) have
been set as byte strings instead of Unicode, these must first be decoded
to Unicode before outputting in the specified encoding.
``default_encoding``, if specified, is the encoding used to decode byte
strings in the **ConfigObj** before writing. If this is ``None``, then
the Python default encoding (``sys.defaultencoding`` - usually ASCII) is
used.
For most Western European users, a value of ``latin-1`` is sensible.
``default_encoding`` is *only* used if an ``encoding`` is specified.
Any characters in byte-strings that can't be decoded using the
``default_encoding`` will raise a ``UnicodeDecodeError``.
* 'unrepr': ``False``
The ``unrepr`` option reads and writes files in a different mode. This
allows you to store and retrieve the basic Python data-types using config
files.
This uses Python syntax for lists and quoting. See `unrepr mode`_ for the
full details.
* 'write_empty_values': ``False``
If ``write_empty_values`` is ``True``, empty strings are written as
empty values. See `Empty Values`_ for more details.
Methods
-------
The ConfigObj is a subclass of an object called ``Section``, which is itself a
subclass of ``dict``, the builtin dictionary type. This means it also has
**all** the normal dictionary methods.
In addition, the following `Section Methods`_ may be useful :
* 'restore_default'
* 'restore_defaults'
* 'walk'
* 'merge'
* 'dict'
* 'as_bool'
* 'as_float'
* 'as_int'
Read about Sections_ for details of all the methods.
.. hint::
The *merge* method of sections is a recursive update.
You can use this to merge sections, or even whole ConfigObjs, into each
other.
You would typically use this to create a default ConfigObj and then merge
in user settings. This way users only need to specify values that are
different from the default. You can use configspecs and validation to
achieve the same thing of course.
The public methods available on ConfigObj are :
* 'write'
* 'validate'
* 'reset'
* 'reload'
write
~~~~~
::
write(file_object=None)
This method writes the current ConfigObj and takes a single, optional argument
[#]_.
If you pass in a file like object to the ``write`` method, the config file will
be written to this. (The only method of this object that is used is its
``write`` method, so a ``StringIO`` instance, or any other file like object
will work.)
Otherwise, the behaviour of this method depends on the ``filename`` attribute
of the ConfigObj.
``filename``
ConfigObj will write the configuration to the file specified.
``None``
``write`` returns a list of lines. (Not ``'\n'`` terminated)
First the 'initial_comment' is written, then the config file, followed by the
'final_comment'. Comment lines and inline comments are written with each
key/value.
validate
~~~~~~~~
::
validate(validator, preserve_errors=False, copy=False)
.. raw:: html
{+coloring}
# filename is the config file
# filename2 is the configspec
# (which could also be hardcoded into your program)
config = ConfigObj(filename, configspec=filename2)
#
from validate import Validator
val = Validator()
test = config.validate(val)
if test == True:
print 'Succeeded.'
{-coloring}
The validate method uses the `validate
`__ module to do the
validation.
This method validates the ConfigObj against the configspec. By doing type
conversion as well it can abstract away the config file altogether and present
the config *data* to your application (in the types it expects it to be).
If the ``configspec`` attribute of the ConfigObj is ``None``, it raises a
``ValueError``.
If the stringify_ attribute is set, this process will convert values to the
type defined in the configspec.
The validate method uses checks specified in the configspec and defined in the
``Validator`` object. It is very easy to extend.
The configspec looks like the config file, but instead of the value, you
specify the check (and any default value). See the validation_ section for
details.
.. hint::
The system of configspecs can seem confusing at first, but is actually
quite simple and powerful. For a concrete example of how to use it, you may
find this blog entry helpful :
`Transforming Values with ConfigObj `_.
The ``copy`` parameter fills in missing values from the configspec (default
values), *without* marking the values as defaults. It also causes comments to
be copied from the configspec into the config file. This allows you to use a
configspec to create default config files. (Normally default values aren't
written out by the ``write`` method.)
As of ConfigObj 4.3.0 you can also pass in a ConfigObj instance as your
configspec. This is especially useful if you need to specify the encoding of
your configspec file. When you read your configspec file, you *must* specify
``list_values=False``.
.. raw:: html
{+coloring}
from configobj import ConfigObj
configspec = ConfigObj(configspecfilename, encoding='UTF8',
list_values=False)
config = ConfigObj(filename, configspec=configspec)
{-coloring}
Return Value
############
By default, the validate method either returns ``True`` (everything passed)
or a dictionary of ``True``/``False`` representing pass/fail. The dictionary
follows the structure of the ConfigObj.
If a whole section passes then it is replaced with the value ``True``. If a
whole section fails, then it is replaced with the value ``False``.
If a value is missing, and there is no default in the check, then the check
automatically fails.
The ``validate`` method takes an optional keyword argument ``preserve_errors``.
If you set this to ``True``, instead of getting ``False`` for failed checks you
get the actual error object from the **validate** module. This usually contains
useful information about why the check failed.
See the `flatten_errors`_ function for how to turn your results dictionary into
a useful list of error messages.
Even if ``preserve_errors`` is ``True``, missing keys or sections will still be
represented by a ``False`` in the results dictionary.
Mentioning Default Values
#########################
In the check in your configspec, you can specify a default to be used - by
using the ``default`` keyword. E.g. ::
key1 = integer(0, 30, default=15)
key2 = integer(default=15)
key3 = boolean(default=True)
key4 = option('Hello', 'Goodbye', 'Not Today', default='Not Today')
If the configspec check supplies a default and the value is missing in the
config, then the default will be set in your ConfigObj. (It is still passed to
the ``Validator`` so that type conversion can be done: this means the default
value must still pass the check.)
ConfigObj keeps a record of which values come from defaults, using the
``defaults`` attribute of sections_. Any key in this list isn't written out by
the ``write`` method. If a key is set from outside (even to the same value)
then it is removed from the ``defaults`` list.
.. note:
Even if all the keys in a section are in the defaults list, the section
marker is still written out.
There is additionally a special case default value of ``None``. If you set the
default value to ``None`` and the value is missing, the value will always be
set to ``None``. As the other checks don't return ``None`` (unless you
implement your own that do), you can tell that this value came from a default
value (and was missing from the config file). It allows an easy way of
implementing optional values. Simply check (and ignore) members that are set
to ``None``.
.. note::
If stringify_ is ``False`` then ``default=None`` returns ``''`` instead of
``None``. This is because setting a value to a non-string raises an error
if stringify is unset.
The default value can be a list. See `List Values`_ for the way to do this.
Writing invalid default values is a *guaranteed* way of confusing your users.
Default values **must** pass the check.
Mentioning Repeated Sections
############################
In the configspec it is possible to cause *every* sub-section in a section to
be validated using the same configspec. You do this with a section in the
configspec called ``__many__``. Every sub-section in that section has the
``__many__`` configspec applied to it (without you having to explicitly name
them in advance).
If you define a ``__many__`` type section it must the only sub-section in that
section. Having a ``__many__`` *and* other sub-sections defined in the same
section will raise a ``RepeatSectionError``.
Your ``__many__`` section can have nested subsections, which can also include
``__many__`` type sections.
See `Repeated Sections`_ for examples.
Mentioning SimpleVal
####################
If you just want to check if all members are present, then you can use the
``SimpleVal`` object that comes with ConfigObj. It only fails members if they
are missing.
Write a configspec that has all the members you want to check for, but set
every section to ``''``.
.. raw:: html
{+coloring}
val = SimpleVal()
test = config.validate(val)
if test is True:
print 'Succeeded.'
{-coloring}
Mentioning copy Mode
####################
As discussed in `Mentioning Default Values`_, you can use a configspec to
supply default values. These are marked in the ConfigObj instance as defaults,
and *not* written out by the ``write`` mode. This means that your users only
need to supply values that are different from the defaults.
This can be inconvenient if you *do* want to write out the default values,
for example to write out a default config file.
If you set ``copy=True`` when you call validate, then no values are marked as
defaults. In addition, all comments from the configspec are copied into
your ConfigObj instance. You can then call ``write`` to create your config
file.
There is a limitation with this. In order to allow `String Interpolation`_ to work
within configspecs, ``DEFAULT`` sections are not processed by
validation; even in copy mode.
reload
~~~~~~
If a ConfigObj instance was loaded from the filesystem, then this method will reload it. It
will also reuse any configspec you supplied at instantiation (including reloading it from
the filesystem if you passed it in as a filename).
If the ConfigObj does not have a filename attribute pointing to a file, then a ``ReloadError``
will be raised.
reset
~~~~~
This method takes no arguments and doesn't return anything. It restores a ConfigObj
instance to a freshly created state.
Attributes
----------
A ConfigObj has the following attributes :
* indent_type
* interpolate
* stringify
* BOM
* initial_comment
* final_comment
* list_values
* encoding
* default_encoding
* unrepr
* write_empty_values
* newlines
.. note::
This doesn't include *comments*, *inline_comments*, *defaults*, or
*configspec*. These are actually attributes of Sections_.
It also has the following attributes as a result of parsing. They correspond to
options_ when the ConfigObj was created, but changing them has no effect.
* raise_errors
* create_empty
* file_error
interpolation
~~~~~~~~~~~~~
ConfigObj can perform string interpolation in a *similar* way to
``ConfigParser``. See the `String Interpolation`_ section for full details.
If ``interpolation`` is set to ``False``, then interpolation is *not* done when
you fetch values.
stringify
~~~~~~~~~
If this attribute is set (``True``) then the validate_ method changes the
values in the ConfigObj. These are turned back into strings when write_ is
called.
If stringify is unset (``False``) then attempting to set a value to a non
string (or a list of strings) will raise a ``TypeError``.
BOM
~~~
If the initial config file *started* with the UTF8 Unicode signature (known
slightly incorrectly as the {acro;BOM;Byte Order Mark}), or the UTF16 BOM, then
this attribute is set to ``True``. Otherwise it is ``False``.
If it is set to ``True`` when ``write`` is called then, if ``encoding`` is set
to ``None`` *or* to ``utf_8`` (and variants) a UTF BOM will be written.
For UTF16 encodings, a BOM is *always* written.
initial_comment
~~~~~~~~~~~~~~~
This is a list of lines. If the ConfigObj is created from an existing file, it
will contain any lines of comments before the start of the members.
If you create a new ConfigObj, this will be an empty list.
The write method puts these lines before it starts writing out the members.
final_comment
~~~~~~~~~~~~~
This is a list of lines. If the ConfigObj is created from an existing file, it
will contain any lines of comments after the last member.
If you create a new ConfigObj, this will be an empty list.
The ``write`` method puts these lines after it finishes writing out the
members.
list_values
~~~~~~~~~~~
This attribute is ``True`` or ``False``. If set to ``False`` then values are
not parsed for list values. In addition single line values are not unquoted.
This allows you to do your own parsing of values. It exists primarily to
support the reading of the configspec_ - but has other use cases.
For example you could use the ``LineParser`` from the
`listquote module `_
to read values for nested lists.
Single line values aren't quoted when writing - but multiline values are
handled as normal.
.. caution::
Because values aren't quoted, leading or trailing whitespace can be
lost.
This behaviour was changed in version 4.0.1.
Prior to this, single line values might have been quoted; even with
``list_values=False``. This means that files written by **ConfigObj**
*could* now be incompatible - and need the quotes removing by hand.
encoding
~~~~~~~~
This is the encoding used to encode the output, when you call ``write``. It
must be a valid encoding `recognised by Python `_.
If this value is ``None`` then no encoding is done when ``write`` is called.
default_encoding
~~~~~~~~~~~~~~~~
If encoding is set, any byte-strings in your ConfigObj instance (keys or
members) will first be decoded to Unicode using the encoding specified by the
``default_encoding`` attribute. This ensures that the output is in the encoding
specified.
If this value is ``None`` then ``sys.defaultencoding`` is used instead.
unrepr
~~~~~~
Another boolean value. If this is set, then ``repr(value)`` is used to write
values. This writes values in a slightly different way to the normal ConfigObj
file syntax.
This preserves basic Python data-types when read back in. See `unrepr mode`_
for more details.
write_empty_values
~~~~~~~~~~~~~~~~~~
Also boolean. If set, values that are an empty string (``''``) are written as
empty values. See `Empty Values`_ for more details.
newlines
~~~~~~~~
When a config file is read, ConfigObj records the type of newline separators in the
file and uses this separator when writing. It defaults to ``None``, and ConfigObj
uses the system default (``os.sep``) if write is called without newlines having
been set.
The Config File Format
======================
You saw an example config file in the `Config Files`_ section. Here is a fuller
specification of the config files used and created by ConfigObj.
The basic pattern for keywords is : ::
# comment line
# comment line
keyword = value # inline comment
Both keyword and value can optionally be surrounded in quotes. The equals sign
is the only valid divider.
Values can have comments on the lines above them, and an inline comment after
them. This, of course, is optional. See the comments_ section for details.
If a keyword or value starts or ends with whitespace, or contains a quote mark
or comma, then it should be surrounded by quotes. Quotes are not necessary if
whitespace is surrounded by non-whitespace.
Values can also be lists. Lists are comma separated. You indicate a single
member list by a trailing comma. An empty list is shown by a single comma : ::
keyword1 = value1, value2, value3
keyword2 = value1, # a single member list
keyword3 = , # an empty list
Values that contain line breaks (multi-line values) can be surrounded by triple
quotes. These can also be used if a value contains both types of quotes. List
members cannot be surrounded by triple quotes : ::
keyword1 = ''' A multi line value
on several
lines''' # with a comment
keyword2 = '''I won't be "afraid".'''
#
keyword3 = """ A multi line value
on several
lines""" # with a comment
keyword4 = """I won't be "afraid"."""
.. warning::
There is no way of safely quoting values that contain both types of triple
quotes.
A line that starts with a '#', possibly preceded by whitespace, is a comment.
New sections are indicated by a section marker line. That is the section name
in square brackets. Whitespace around the section name is ignored. The name can
be quoted with single or double quotes. The marker can have comments before it
and an inline comment after it : ::
# The First Section
[ section name 1 ] # first section
keyword1 = value1
# The Second Section
[ "section name 2" ] # second section
keyword2 = value2
Any subsections (sections that are *inside* the current section) are
designated by repeating the square brackets before and after the section name.
The number of square brackets represents the nesting level of the sub-section.
Square brackets may be separated by whitespace; such whitespace, however, will
not be present in the output config written by the ``write`` method.
Indentation is not significant, but can be preserved. See the description of
the ``indent_type`` option, in the `ConfigObj specifications`_ chapter, for the
details.
A *NestingError* will be raised if the number of the opening and the closing
brackets in a section marker is not the same, or if a sub-section's nesting
level is greater than the nesting level of it parent plus one.
In the outer section, single values can only appear before any sub-section.
Otherwise they will belong to the sub-section immediately before them. ::
# initial comment
keyword1 = value1
keyword2 = value2
[section 1]
keyword1 = value1
keyword2 = value2
[[sub-section]]
# this is in section 1
keyword1 = value1
keyword2 = value2
[[[nested section]]]
# this is in sub section
keyword1 = value1
keyword2 = value2
[[sub-section2]]
# this is in section 1 again
keyword1 = value1
keyword2 = value2
[[sub-section3]]
# this is also in section 1, indentation is misleading here
keyword1 = value1
keyword2 = value2
# final comment
When parsed, the above config file produces the following data structure :
.. raw:: html
{+coloring}
ConfigObj({
'keyword1': 'value1',
'keyword2': 'value2',
'section 1': {
'keyword1': 'value1',
'keyword2': 'value2',
'sub-section': {
'keyword1': 'value1',
'keyword2': 'value2',
'nested section': {
'keyword1': 'value1',
'keyword2': 'value2',
},
},
'sub-section2': {
'keyword1': 'value1',
'keyword2': 'value2',
},
'sub-section3': {
'keyword1': 'value1',
'keyword2': 'value2',
},
},
})
{-coloring}
Sections are ordered: note how the structure of the resulting ConfigObj is in
the same order as the original file.
.. note::
In ConfigObj 4.3.0 *empty values* became valid syntax. They are read as the
empty string. There is also an option/attribute (``write_empty_values``) to
allow the writing of these.
This is mainly to support 'legacy' config files, written from other
applications. This is documented under `Empty Values`_.
`unrepr mode`_ introduces *another* syntax variation, used for storing
basic Python datatypes in config files. {sm;:-)}
Sections
========
Every section in a ConfigObj has certain properties. The ConfigObj itself also
has these properties, because it too is a section (sometimes called the *root
section*).
``Section`` is a subclass of the standard new-class dictionary, therefore it
has **all** the methods of a normal dictionary. This means you can ``update``
and ``clear`` sections.
.. note::
You create a new section by assigning a member to be a dictionary.
The new ``Section`` is created *from* the dictionary, but isn't the same
thing as the dictionary. (So references to the dictionary you use to create
the section *aren't* references to the new section).
Note the following.
.. raw:: html
{+coloring}
config = ConfigObj()
vals = {'key1': 'value 1',
'key2': 'value 2'
}
config['vals'] = vals
config['vals'] == vals
True
config['vals'] is vals
False
{-coloring}
If you now change ``vals``, the changes won't be reflected in ``config['vals']``.
A section is ordered, following its ``scalars`` and ``sections``
attributes documented below. This means that the following dictionary
attributes return their results in order.
* '__iter__'
More commonly known as ``for member in section:``.
* '__repr__' and '__str__'
Any time you print or display the ConfigObj.
* 'items'
* 'iteritems'
* 'iterkeys'
* 'itervalues'
* 'keys'
* 'popitem'
* 'values'
Section Attributes
------------------
* main
A reference to the main ConfigObj.
* parent
A reference to the 'parent' section, the section that this section is a
member of.
On the ConfigObj this attribute is a reference to itself. You can use this
to walk up the sections, stopping when ``section.parent is section``.
* depth
The nesting level of the current section.
If you create a new ConfigObj and add sections, 1 will be added to the
depth level between sections.
* defaults
This attribute is a list of scalars that came from default values. Values
that came from defaults aren't written out by the ``write`` method.
Setting any of these values in the section removes them from the defaults
list.
* default_values
This attribute is a dictionary mapping keys to the default values for the
keys. By default it is an empty dictionary and is populated when you
validate the ConfigObj.
* scalars, sections
These attributes are normal lists, representing the order that members,
single values and subsections appear in the section. The order will either
be the order of the original config file, *or* the order that you added
members.
The order of members in this lists is the order that ``write`` creates in
the config file. The ``scalars`` list is output before the ``sections``
list.
Adding or removing members also alters these lists. You can manipulate the
lists directly to alter the order of members.
.. warning::
If you alter the ``scalars``, ``sections``, or ``defaults`` attributes
so that they no longer reflect the contents of the section, you will
break your ConfigObj.
See also the ``rename`` method.
* comments
This is a dictionary of comments associated with each member. Each entry is
a list of lines. These lines are written out before the member.
* inline_comments
This is *another* dictionary of comments associated with each member. Each
entry is a string that is put inline with the member.
* configspec
The configspec attribute is a dictionary mapping scalars to *checks*. A
check defines the expected type and possibly the allowed values for a
member.
The configspec has the same format as a config file, but instead of values
it has a specification for the value (which may include a default value).
The validate_ method uses it to check the config file makes sense. If a
configspec is passed in when the ConfigObj is created, then it is parsed
and broken up to become the ``configspec`` attribute of each section.
If you didn't pass in a configspec, this attribute will be ``None`` on the
root section (the main ConfigObj).
You can set the configspec attribute directly on a section.
See the validation_ section for full details of how to write configspecs.
Section Methods
---------------
* **dict**
This method takes no arguments. It returns a deep copy of the section as a
dictionary. All subsections will also be dictionaries, and list values will
be copies, rather than references to the original [#]_.
* **rename**
``rename(oldkey, newkey)``
This method renames a key, without affecting its position in the sequence.
It is mainly implemented for the ``encode`` and ``decode`` methods, which
provide some Unicode support.
* **merge**
``merge(indict)``
This method is a *recursive update* method. It allows you to merge two
config files together.
You would typically use this to create a default ConfigObj and then merge
in user settings. This way users only need to specify values that are
different from the default.
For example :
.. raw:: html
{+coloring}
# def_cfg contains your default config settings
# user_cfg contains the user settings
cfg = ConfigObj(def_cfg)
usr = ConfigObj(user_cfg)
#
cfg.merge(usr)
"""
cfg now contains a combination of the default settings and the user
settings.
The user settings will have overwritten any of the default ones.
"""
{-coloring}
* **walk**
This method can be used to transform values and names. See `walking a
section`_ for examples and explanation.
* **decode**
``decode(encoding)``
This method decodes names and values into Unicode objects, using the
supplied encoding.
* **encode**
``encode(encoding)``
This method is the opposite of ``decode`` {sm;:!:}.
It encodes names and values using the supplied encoding. If any of your
names/values are strings rather than Unicode, Python will have to do an
implicit decode first. (This method uses ``sys.defaultencoding`` for
implicit decodes.)
* **as_bool**
``as_bool(key)``
Returns ``True`` if the key contains a string that represents ``True``, or
is the ``True`` object.
Returns ``False`` if the key contains a string that represents ``False``,
or is the ``False`` object.
Raises a ``ValueError`` if the key contains anything else.
Strings that represent ``True`` are (not case sensitive) : ::
true, yes, on, 1
Strings that represent ``False`` are : ::
false, no, off, 0
.. note::
In ConfigObj 4.1.0, this method was called ``istrue``. That method is
now deprecated and will issue a warning when used. It will go away
in a future release.
* **as_int**
``as_int(key)``
This returns the value contained in the specified key as an integer.
It raises a ``ValueError`` if the conversion can't be done.
* **as_float**
``as_float(key)``
This returns the value contained in the specified key as a float.
It raises a ``ValueError`` if the conversion can't be done.
* **restore_default**
``restore_default(key)``
Restore (and return) the default value for the specified key.
This method will only work for a ConfigObj that was created
with a configspec and has been validated.
If there is no default value for this key, ``KeyError`` is raised.
* **restore_defaults**
``restore_defaults()``
Recursively restore default values to all members
that have them.
This method will only work for a ConfigObj that was created
with a configspec and has been validated.
It doesn't delete or modify entries without default values.
Walking a Section
-----------------
.. note::
The walk method allows you to call a function on every member/name.
.. raw:: html
{+coloring}
walk(function, raise_errors=True,
call_on_sections=False, **keywargs):
{-coloring}
``walk`` is a method of the ``Section`` object. This means it is also a method
of ConfigObj.
It walks through every member and calls a function on the keyword and value. It
walks recursively through subsections.
It returns a dictionary of all the computed values.
If the function raises an exception, the default is to propagate the error, and
stop. If ``raise_errors=False`` then it sets the return value for that keyword
to ``False`` instead, and continues. This is similar to the way validation_
works.
Your function receives the arguments ``(section, key)``. The current value is
then ``section[key]`` [#]_. Any unrecognised keyword arguments you pass to
walk, are passed on to the function.
Normally ``walk`` just recurses into subsections. If you are transforming (or
checking) names as well as values, then you want to be able to change the names
of sections. In this case set ``call_on_sections`` to ``True``. Now, on
encountering a sub-section, *first* the function is called for the *whole*
sub-section, and *then* it recurses into it's members. This means your function
must be able to handle receiving dictionaries as well as strings and lists.
If you are using the return value from ``walk`` *and* ``call_on_sections``,
note that walk discards the return value when it calls your function.
.. caution::
You can use ``walk`` to transform the names of members of a section
but you mustn't add or delete members.
Examples
--------
Examples that use the walk method are the ``encode`` and ``decode`` methods.
They both define a function and pass it to walk. Because these functions
transform names as well as values (from byte strings to Unicode) they set
``call_on_sections=True``.
To see how they do it, *read the source Luke* {sm;:cool:}.
You can use this for transforming all values in your ConfigObj. For example
you might like the nested lists from ConfigObj 3. This was provided by the
listquote_ module. You could switch off the parsing for list values
(``list_values=False``) and use listquote to parse every value.
Another thing you might want to do is use the Python escape codes in your
values. You might be *used* to using ``\n`` for line feed and ``\t`` for tab.
Obviously we'd need to decode strings that come from the config file (using the
escape codes). Before writing out we'll need to put the escape codes back in
encode.
As an example we'll write a function to use with walk, that encodes or decodes
values using the ``string-escape`` codec.
The function has to take each value and set the new value. As a bonus we'll
create one function that will do decode *or* encode depending on a keyword
argument.
We don't want to work with section names, we're only transforming values, so
we can leave ``call_on_sections`` as ``False``. This means the two datatypes we
have to handle are strings and lists, we can ignore everything else. (We'll
treat tuples as lists as well).
We're not using the return values, so it doesn't need to return anything, just
change the values if appropriate.
.. raw:: html
{+coloring}
def string_escape(section, key, encode=False):
"""
A function to encode or decode using the 'string-escape' codec.
To be passed to the walk method of a ConfigObj.
By default it decodes.
To encode, pass in the keyword argument ``encode=True``.
"""
val = section[key]
# is it a type we can work with
# NOTE: for platforms where Python > 2.2
# you can use basestring instead of (str, unicode)
if not isinstance(val, (str, unicode, list, tuple)):
# no !
return
elif isinstance(val, (str, unicode)):
# it's a string !
if not encode:
section[key] = val.decode('string-escape')
else:
section[key] = val.encode('string-escape')
else:
# it must be a list or tuple!
# we'll be lazy and create a new list
newval = []
# we'll check every member of the list
for entry in val:
if isinstance(entry, (str, unicode)):
if not encode:
newval.append(entry.decode('string-escape'))
else:
newval.append(entry.encode('string-escape'))
else:
newval.append(entry)
# done !
section[key] = newval
# assume we have a ConfigObj called ``config``
#
# To decode
config.walk(string_escape)
#
# To encode.
# Because ``walk`` doesn't recognise the ``encode`` argument
# it passes it to our function.
config.walk(string_escape, encode=True)
{-coloring}
Here's a simple example of using ``walk`` to transform names and values. One
usecase of this would be to create a *standard* config file with placeholders
for section and keynames. You can then use walk to create new config files
and change values and member names :
.. raw:: html
{+coloring}
# We use 'XXXX' as a placeholder
config = '''
XXXXkey1 = XXXXvalue1
XXXXkey2 = XXXXvalue2
XXXXkey3 = XXXXvalue3
[XXXXsection1]
XXXXkey1 = XXXXvalue1
XXXXkey2 = XXXXvalue2
XXXXkey3 = XXXXvalue3
[XXXXsection2]
XXXXkey1 = XXXXvalue1
XXXXkey2 = XXXXvalue2
XXXXkey3 = XXXXvalue3
[[XXXXsection1]]
XXXXkey1 = XXXXvalue1
XXXXkey2 = XXXXvalue2
XXXXkey3 = XXXXvalue3
'''.splitlines()
cfg = ConfigObj(config)
#
def transform(section, key):
val = section[key]
newkey = key.replace('XXXX', 'CLIENT1')
section.rename(key, newkey)
if isinstance(val, (tuple, list, dict)):
pass
else:
val = val.replace('XXXX', 'CLIENT1')
section[newkey] = val
#
cfg.walk(transform, call_on_sections=True)
print cfg
ConfigObj({'CLIENT1key1': 'CLIENT1value1', 'CLIENT1key2': 'CLIENT1value2',
'CLIENT1key3': 'CLIENT1value3',
'CLIENT1section1': {'CLIENT1key1': 'CLIENT1value1',
'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3'},
'CLIENT1section2': {'CLIENT1key1': 'CLIENT1value1',
'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3',
'CLIENT1section1': {'CLIENT1key1': 'CLIENT1value1',
'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3'}}})
{-coloring}
Exceptions
==========
There are several places where ConfigObj may raise exceptions (other than
because of bugs).
1) If a configspec filename you pass in doesn't exist, or a config file
filename doesn't exist *and* ``file_error=True``, an ``IOError`` will be
raised.
2) If you try to set a non-string key, or a non string value when
``stringify=False``, a ``TypeError`` will be raised.
3) A badly built config file will cause parsing errors.
4) A parsing error can also occur when reading a configspec.
5) In string interpolation you can specify a value that doesn't exist, or
create circular references (recursion).
6) If you have a ``__many__`` repeated section with other section definitions
(in a configspec), a ``RepeatSectionError`` will be raised.
Number 5 (which is actually two different types of exceptions) is documented
in `String Interpolation`_.
Number 6 is explained in the validation_ section.
*This* section is about errors raised during parsing.
The base error class is ``ConfigObjError``. This is a subclass of
``SyntaxError``, so you can trap for ``SyntaxError`` without needing to
directly import any of the ConfigObj exceptions.
The following other exceptions are defined (all deriving from
``ConfigObjError``) :
* ``NestingError``
This error indicates either a mismatch in the brackets in a section marker,
or an excessive level of nesting.
* ``ParseError``
This error indicates that a line is badly written. It is neither a valid
``key = value`` line, nor a valid section marker line, nor a comment line.
* ``DuplicateError``
The keyword or section specified already exists.
* ``ConfigspecError``
An error occurred whilst parsing a configspec.
* ``UnreprError``
An error occurred when parsing a value in `unrepr mode`_.
* ``ReloadError``
``reload`` was called on a ConfigObj instance that doesn't have a valid
filename attribute.
When parsing a configspec, ConfigObj will stop on the first error it
encounters. It will raise a ``ConfigspecError``. This will have an ``error``
attribute, which is the actual error that was raised.
Behaviour when parsing a config file depends on the option ``raise_errors``.
If ConfigObj encounters an error while parsing a config file:
If ``raise_errors=True`` then ConfigObj will raise the appropriate error
and parsing will stop.
If ``raise_errors=False`` (the default) then parsing will continue to the
end and *all* errors will be collected.
If ``raise_errors`` is False and multiple errors are found a ``ConfigObjError``
is raised. The error raised has a ``config`` attribute, which is the parts of
the ConfigObj that parsed successfully. It also has an attribute ``errors``,
which is a list of *all* the errors raised. Each entry in the list is an
instance of the appropriate error type. Each one has the following attributes
(useful for delivering a sensible error message to your user) :
* ``line``: the original line that caused the error.
* ``line_number``: its number in the config file.
* ``message``: the error message that accompanied the error.
If only one error is found, then that error is re-raised. The error still has
the ``config`` and ``errors`` attributes. This means that your error handling
code can be the same whether one error is raised in parsing , or several.
It also means that in the most common case (a single error) a useful error
message will be raised.
.. note::
One wrongly written line could break the basic structure of your config
file. This could cause every line after it to flag an error, so having a
list of all the lines that caused errors may not be as useful as it sounds.
{sm;:-(}.
Validation
==========
.. hint::
The system of configspecs can seem confusing at first, but is actually
quite simple and powerful. For a concrete example of how to use it, you may
find this blog entry helpful :
`Transforming Values with ConfigObj `_.
Validation is done through a combination of the configspec_ and a ``Validator``
object. For this you need *validate.py* [#]_. See downloading_ if you don't
have a copy.
Validation can perform two different operations :
1) Check that a value meets a specification. For example, check that a value
is an integer between one and six, or is a choice from a specific set of
options.
2) It can convert the value into the type required. For example, if one of
your values is a port number, validation will turn it into an integer for
you.
So validation can act as a transparent layer between the datatypes of your
application configuration (boolean, integers, floats, etc) and the text format
of your config file.
configspec
----------
The ``validate`` method checks members against an entry in the configspec. Your
configspec therefore resembles your config file, with a check for every member.
In order to perform validation you need a ``Validator`` object. This has
several useful built-in check functions. You can also create your own custom
functions and register them with your Validator object.
Each check is the name of one of these functions, including any parameters and
keyword arguments. The configspecs look like function calls, and they map to
function calls.
The basic datatypes that an un-extended Validator can test for are :
* boolean values (True and False)
* integers (including minimum and maximum values)
* floats (including min and max)
* strings (including min and max length)
* IP addresses (v4 only)
It can also handle lists of these types and restrict a value to being one from
a set of options.
An example configspec is going to look something like : ::
port = integer(0, 100)
user = string(max=25)
mode = option('quiet', 'loud', 'silent')
You can specify default values, and also have the same configspec applied to
several sections. This is called `repeated sections`_.
For full details on writing configspecs, please refer to the `validate.py
documentation`_.
.. important::
Your configspec is read by ConfigObj in the same way as a config file.
That means you can do interpolation *within* your configspec.
In order to allow this, checks in the 'DEFAULT' section (of the root level
of your configspec) are *not* used.
If you need to specify the encoding of your configspec, then you can pass in a
ConfigObj instance as your configspec. When you read your configspec file, you
*must* specify ``list_values=False``.
.. raw:: html
{+coloring}
from configobj import ConfigObj
configspec = ConfigObj(configspecfilename, encoding='UTF8',
list_values=False)
config = ConfigObj(filename, configspec=configspec)
{-coloring}
.. _validate.py documentation: http://www.voidspace.org.uk/python/validate.html
Type Conversion
---------------
By default, validation does type conversion. This means that if you specify
``integer`` as the check, then calling validate_ will actually change the value
to an integer (so long as the check succeeds).
It also means that when you call the write_ method, the value will be converted
back into a string using the ``str`` function.
To switch this off, and leave values as strings after validation, you need to
set the stringify_ attribute to ``False``. If this is the case, attempting to
set a value to a non-string will raise an error.
Default Values
--------------
You can set a default value in your check. If the value is missing from the
config file then this value will be used instead. This means that your user
only has to supply values that differ from the defaults.
If you *don't* supply a default then for a value to be missing is an error,
and this will show in the `return value`_ from validate.
Additionally you can set the default to be ``None``. This means the value will
be set to ``None`` (the object) *whichever check is used*. (It will be set to
``''`` rather than ``None`` if stringify_ is ``False``). You can use this
to easily implement optional values in your config files. ::
port = integer(0, 100, default=80)
user = string(max=25, default=0)
mode = option('quiet', 'loud', 'silent', default='loud')
nick = string(default=None)
.. note::
Because the default goes through type conversion, it also has to pass the
check.
Note that ``default=None`` is case sensitive.
List Values
~~~~~~~~~~~
It's possible that you will want to specify a list as a default value. To avoid
confusing syntax with commas and quotes you use a list constructor to specify
that keyword arguments are lists. This includes the ``default`` value. This
makes checks look something like : ::
checkname(default=list('val1', 'val2', 'val3'))
This works with all keyword arguments, but is most useful for default values.
Repeated Sections
-----------------
Repeated sections are a way of specifying a configspec for a section that
should be applied to *all* subsections in the same section.
The easiest way of explaining this is to give an example. Suppose you have a
config file that describes a dog. That dog has various attributes, but it can
also have many fleas. You don't know in advance how many fleas there will be,
or what they will be called, but you want each flea validated against the same
configspec.
We can define a section called *fleas*. We want every flea in that section
(every sub-section) to have the same configspec applied to it. We do this by
defining a single section called ``__many__``. ::
[dog]
name = string(default=Rover)
age = float(0, 99, default=0)
[[fleas]]
[[[__many__]]]
bloodsucker = boolean(default=True)
children = integer(default=10000)
size = option(small, tiny, micro, default=tiny)
Every flea on our dog will now be validated using the ``__many__`` configspec.
If you define another sub-section in a section *as well as* a ``__many__`` then
you will get an error.
``__many__`` sections can have sub-sections, including their own ``__many__``
sub-sections. Defaults work in the normal way in repeated sections.
Copy Mode
---------
Because you can specify default values in your configspec, you can use
ConfigObj to write out default config files for your application.
However, normally values supplied from a default in a configspec are *not*
written out by the ``write`` method.
To do this, you need to specify ``copy=True`` when you call validate. As well
as not marking values as default, all the comments in the configspec file
will be copied into your ConfigObj instance.
.. raw:: html
{+coloring}
from configobj import ConfigObj
from validate import Validator
vdt = Validator()
config = ConfigObj(configspec='default.ini')
config.filename = 'new_default.ini'
config.validate(vdt, copy=True)
config.write()
{-coloring}
Validation and Interpolation
----------------------------
String interpolation and validation don't play well together. When validation
changes type it sets the value. If the value uses interpolation, then the
interpolation reference would normally be overwritten. Calling ``write`` would
then use the absolute value and the interpolation reference would be lost.
As a compromise - if the value is unchanged by validation then it is not reset.
This means strings that pass through validation unmodified will not be
overwritten. If validation changes type - the value has to be overwritten, and
any interpolation references are lost {sm;:-(}.
SimpleVal
---------
You may not need a full validation process, but still want to check if all the
expected values are present.
Provided as part of the ConfigObj module is the ``SimpleVal`` object. This has
a dummy ``test`` method that always passes.
The only reason a test will fail is if the value is missing. The return value
from ``validate`` will either be ``True``, meaning all present, or a dictionary
with ``False`` for all missing values/sections.
To use it, you still need to pass in a valid configspec when you create the
ConfigObj, but just set all the values to ``''``. Then create an instance of
``SimpleVal`` and pass it to the ``validate`` method.
As a trivial example if you had the following config file : ::
# config file for an application
port = 80
protocol = http
domain = voidspace
top_level_domain = org.uk
You would write the following configspec : ::
port = ''
protocol = ''
domain = ''
top_level_domain = ''
.. raw:: html
{+coloring}
config = Configobj(filename, configspec=configspec)
val = SimpleVal()
test = config.validate(val)
if test == True:
print 'All values present.'
elif test == False:
print 'No values present!'
else:
for entry in test:
if test[entry] == False:
print '"%s" missing.' % entry
{-coloring}
Empty values
============
Many config files from other applications allow empty values. As of version
4.3.0, ConfigObj will read these as an empty string.
A new option/attribute has been added (``write_empty_values``) to allow
ConfigObj to write empty strings as empty values.
.. raw:: html
{+coloring}
from configobj import ConfigObj
cfg = '''
key =
key2 = # a comment
'''.splitlines()
config = ConfigObj(cfg)
print config
ConfigObj({'key': '', 'key2': ''})
config.write_empty_values = True
for line in config.write():
print line
key =
key2 = # a comment
{-coloring}
unrepr mode
===========
The ``unrepr`` option allows you to store and retrieve the basic Python
data-types using config files. It has to use a slightly different syntax to
normal ConfigObj files. Unsurprisingly it uses Python syntax.
This means that lists are different (they are surrounded by square brackets),
and strings *must* be quoted.
The types that ``unrepr`` can work with are :
| strings, lists tuples
| None, True, False
| dictionaries, integers, floats
| longs and complex numbers
You can't store classes, types or instances.
``unrepr`` uses ``repr(object)`` to write out values, so it currently *doesn't*
check that you are writing valid objects. If you attempt to read an unsupported
value, ConfigObj will raise a ``configobj.UnknownType`` exception.
Values that are triple quoted cased. The triple quotes are removed *before*
converting. This means that you can use triple quotes to write dictionaries
over several lines in your config files. They won't be written like this
though.
If you are writing config files by hand, for use with ``unrepr``, you should
be aware of the following differences from normal ConfigObj syntax :
| List : ``['A List', 'With', 'Strings']``
| Strings : ``"Must be quoted."``
| Backslash : ``"The backslash must be escaped \\"``
These all follow normal Python syntax.
In unrepr mode *inline comments* are not saved. This is because lines are
parsed using the `compiler package `_
which discards comments.
String Interpolation
====================
ConfigObj allows string interpolation *similar* to the way ``ConfigParser``
or ``string.Template`` work. The value of the ``interpolation`` attribute
determines which style of interpolation you want to use. Valid values are
"ConfigParser" or "Template" (case-insensitive, so "configparser" and
"template" will also work). For backwards compatibility reasons, the value
``True`` is also a valid value for the ``interpolation`` attribute, and
will select ``ConfigParser``-style interpolation. At some undetermined point
in the future, that default *may* change to ``Template``-style interpolation.
For ``ConfigParser``-style interpolation, you specify a value to be
substituted by including ``%(name)s`` in the value.
For ``Template``-style interpolation, you specify a value to be substituted
by including ``${cl}name{cr}`` in the value. Alternately, if 'name' is a valid
Python identifier (i.e., is composed of nothing but alphanumeric characters,
plus the underscore character), then the braces are optional and the value
can be written as ``$name``.
Note that ``ConfigParser``-style interpolation and ``Template``-style
interpolation are mutually exclusive; you cannot have a configuration file
that's a mix of one or the other. Pick one and stick to it. ``Template``-style
interpolation is simpler to read and write by hand, and is recommended if
you don't have a particular reason to use ``ConfigParser``-style.
Interpolation checks first the current section to see if ``name`` is the key
to a value. ('name' is case sensitive).
If it doesn't find it, next it checks the 'DEFAULT' sub-section of the current
section.
If it still doesn't find it, it moves on to check the parent section and the
parent section's 'DEFAULT' subsection, and so on all the way up to the main
section.
If the value specified isn't found in any of these locations, then a
``MissingInterpolationOption`` error is raised (a subclass of
``ConfigObjError``).
If it is found then the returned value is also checked for substitutions. This
allows you to make up compound values (for example directory paths) that use
more than one default value. It also means it's possible to create circular
references. If there are any circular references which would cause an infinite
interpolation loop, an ``InterpolationLoopError`` is raised.
Both of these errors are subclasses of ``InterpolationError``, which is a
subclass of ``ConfigObjError``.
String interpolation and validation don't play well together. This is because
validation overwrites values - and so may erase the interpolation references.
See `Validation and Interpolation`_. (This can only happen if validation
has to *change* the value).
Comments
========
Any line that starts with a '#', possibly preceded by whitespace, is a comment.
If a config file starts with comments then these are preserved as the
initial_comment_.
If a config file ends with comments then these are preserved as the
final_comment_.
Every key or section marker may have lines of comments immediately above it.
These are saved as the ``comments`` attribute of the section. Each member is a
list of lines.
You can also have a comment inline with a value. These are saved as the
``inline_comments`` attribute of the section, with one entry per member of the
section.
Subsections (section markers in the config file) can also have comments.
See `Section Attributes`_ for more on these attributes.
These comments are all written back out by the ``write`` method.
flatten_errors
==============
::
flatten_errors(cfg, res)
Validation_ is a powerful way of checking that the values supplied by the user
make sense.
The validate_ method returns a results dictionary that represents pass or fail
for each value. This doesn't give you any information about *why* the check
failed.
``flatten_errors`` is an example function that turns a results dictionary into
a flat list, that only contains values that *failed*.
``cfg`` is the ConfigObj instance being checked, ``res`` is the results
dictionary returned by ``validate``.
It returns a list of keys that failed. Each member of the list is a tuple : ::
([list of sections...], key, result)
If ``validate`` was called with ``preserve_errors=False`` (the default)
then ``result`` will always be ``False``.
*list of sections* is a flattened list of sections that the key was found
in.
If the section was missing then key will be ``None``.
If the value (or section) was missing then ``result`` will be ``False``.
If ``validate`` was called with ``preserve_errors=True`` and a value
was present, but failed the check, then ``result`` will be the exception
object returned. You can use this as a string that describes the failure.
For example :
*The value "3" is of the wrong type*.
Example Usage
-------------
The output from ``flatten_errors`` is a list of tuples.
Here is an example of how you could present this information to the user.
.. raw:: html
{+coloring}
vtor = validate.Validator()
# ini is your config file - cs is the configspec
cfg = ConfigObj(ini, configspec=cs)
res = cfg.validate(vtor, preserve_errors=True)
for entry in flatten_errors(cfg, res):
# each entry is a tuple
section_list, key, error = entry
if key is not None:
section_list.append(key)
else:
section_list.append('[missing section]')
section_string = ', '.join(section_list)
if error == False:
error = 'Missing value or section.'
print section_string, ' = ', error
{-coloring}
ConfigObj 3
===========
ConfigObj 3 is now deprecated in favour of ConfigObj 4. I can fix bugs in
ConfigObj 3 if needed, though.
For anyone who still needs it, you can download it here: `ConfigObj 3.3.1`_
You can read the old docs at : `ConfigObj 3 Docs`_
.. _ConfigObj 3.3.1: http://www.voidspace.org.uk/cgi-bin/voidspace/downman.py?file=configobj3.zip
.. _ConfigObj 3 Docs: http://www.voidspace.org.uk/python/configobj3.html
CREDITS
=======
ConfigObj 4 is written by (and copyright) `Michael Foord`_ and
`Nicola Larosa`_.
Particularly thanks to Nicola Larosa for help on the config file spec, the
validation system and the doctests.
*validate.py* was originally written by Michael Foord and Mark Andrews.
Thanks to others for input and bugfixes.
LICENSE
=======
ConfigObj, and related files, are licensed under the BSD license. This is a
very unrestrictive license, but it comes with the usual disclaimer. This is
free software: test it, break it, just don't blame us if it eats your data !
Of course if it does, let us know and we'll fix the problem so it doesn't
happen to anyone else {sm;:-)}. ::
Copyright (c) 2004 - 2008, Michael Foord & Nicola Larosa
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.
* Neither the name of Michael Foord nor Nicola Larosa
may be used to endorse or promote products derived from this
software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
You should also be able to find a copy of this license at : `BSD License`_
.. _BSD License: http://www.voidspace.org.uk/python/license.shtml
TODO
====
Better support for configuration from multiple files, including tracking
*where* the original file came from and writing changes to the correct
file.
Make ``newline`` an option (as well as an attribute) ?
``UTF16`` encoded files, when returned as a list of lines, will have the
BOM at the start of every line. Should this be removed from all but the
first line ?
Option to set warning type for unicode decode ? (Defaults to strict).
A method to optionally remove uniform indentation from multiline values.
(do as an example of using ``walk`` - along with string-escape)
Should the results dictionary from validate be an ordered dictionary if
`odict `_ is available ?
Implement some of the sequence methods (which include slicing) from the
newer ``odict`` ?
Preserve line numbers of values (and possibly the original text of each value).
ISSUES
======
.. note::
Please file any bug reports to `Michael Foord`_ or the **ConfigObj**
`Mailing List`_.
There is currently no way to specify the encoding of a configspec file.
When using ``copy`` mode for validation, it won't copy ``DEFAULT``
sections. This is so that you *can* use interpolation in configspec
files.
``validate`` doesn't report *extra* values or sections.
You can't have a keyword with the same name as a section (in the same
section). They are both dictionary keys - so they would overlap.
ConfigObj doesn't quote and unquote values if ``list_values=False``.
This means that leading or trailing whitespace in values will be lost when
writing. (Unless you manually quote).
Interpolation checks first the current section, then the 'DEFAULT' subsection
of the current section, before moving on to the current section's parent and
so on up the tree.
Does it matter that we don't support the ':' divider, which is supported
by ``ConfigParser`` ?
String interpolation and validation don't play well together. When
validation changes type it sets the value. This will correctly fetch the
value using interpolation - but then overwrite the interpolation reference.
If the value is unchanged by validation (it's a string) - but other types
will be.
CHANGELOG
=========
This is an abbreviated changelog showing the major releases up to version 4.
From version 4 it lists all releases and changes.
2008/02/05 - Version 4.5.2
--------------------------
Distribution updated to include version 0.3.2 of validate_. This means that
``None`` as a default value win configspecs works.
2008/02/05 - Version 4.5.1
--------------------------
Distribution updated to include version 0.3.1 of validate_. This means that
Unicode configspecs now work.
2008/02/05 - Version 4.5.0
--------------------------
ConfigObj will now guarantee that files will be written terminated with a
newline.
ConfigObj will no longer attempt to import the ``validate`` module, until/unless
you call ``ConfigObj.validate`` with ``preserve_errors=True``. This makes it
faster to import.
New methods ``restore_default`` and ``restore_defaults``. ``restore_default``
resets an entry to its default value (and returns that value). ``restore_defaults``
resets all entries to their default value. It doesn't modify entries without a
default value. You must have validated a ConfigObj (which populates the
``default_values`` dictionary) before calling these methods.
BUGFIX: Proper quoting of keys, values and list values that contain hashes
(when writing). When ``list_values=False``, values containing hashes are
triple quoted.
Added the ``reload`` method. This reloads a ConfigObj from file. If the filename
attribute is not set then a ``ReloadError`` (a new exception inheriting from
``IOError``) is raised.
BUGFIX: Files are read in with 'rb' mode, so that native/non-native line endings work!
Minor efficiency improvement in ``unrepr`` mode.
Added missing docstrings for some overidden dictionary methods.
Added the ``reset`` method. This restores a ConfigObj to a freshly created state.
Removed old CHANGELOG file.
2007/02/04 - Version 4.4.0
--------------------------
Official release of 4.4.0
2006/12/17 - Version 4.3.3-alpha4
---------------------------------
By Nicola Larosa
Allowed arbitrary indentation in the ``indent_type`` parameter, removed the
``NUM_INDENT_SPACES`` and ``MAX_INTERPOL_DEPTH`` (a leftover) constants,
added indentation tests (including another docutils workaround, sigh), updated
the documentation.
By Michael Foord
Made the import of ``compiler`` conditional so that ``ConfigObj`` can be used
with `IronPython `_.
2006/12/17 - Version 4.3.3-alpha3
---------------------------------
By Nicola Larosa
Added a missing ``self.`` in the _handle_comment method and a related test,
per Sourceforge bug #1523975.
2006/12/09 - Version 4.3.3-alpha2
---------------------------------
By Nicola Larosa
Changed interpolation search strategy, based on this patch by Robin Munn:
http://sourceforge.net/mailarchive/message.php?msg_id=17125993
2006/12/09 - Version 4.3.3-alpha1
---------------------------------
By Nicola Larosa
Added Template-style interpolation, with tests, based on this patch by
Robin Munn: http://sourceforge.net/mailarchive/message.php?msg_id=17125991
(awful archives, bad Sourceforge, bad).
2006/06/04 - Version 4.3.2
--------------------------
Changed error handling, if parsing finds a single error then that error will
be re-raised. That error will still have an ``errors`` and a ``config``
attribute.
Fixed bug where '\\n' terminated files could be truncated.
Bugfix in ``unrepr`` mode, it couldn't handle '#' in values. (Thanks to
Philippe Normand for the report.)
As a consequence of this fix, ConfigObj doesn't now keep inline comments in
``unrepr`` mode. This is because the parser in the `compiler package`_
doesn't keep comments. {sm;:-)}
Error messages are now more useful. They tell you the number of parsing errors
and the line number of the first error. (In the case of multiple errors.)
Line numbers in exceptions now start at 1, not 0.
Errors in ``unrepr`` mode are now handled the same way as in the normal mode.
The errors stored will be an ``UnreprError``.
2006/04/29 - Version 4.3.1
--------------------------
Added ``validate.py`` back into ``configobj.zip``. (Thanks to Stewart
Midwinter)
Updated to `validate.py`_ 0.2.2.
Preserve tuples when calling the ``dict`` method. (Thanks to Gustavo Niemeyer.)
Changed ``__repr__`` to return a string that contains ``ConfigObj({ ... })``.
Change so that an options dictionary isn't modified by passing it to ConfigObj.
(Thanks to Artarious.)
Added ability to handle negative integers in ``unrepr``. (Thanks to Kevin
Dangoor.)
2006/03/24 - Version 4.3.0
--------------------------
Moved the tests and the CHANGELOG (etc) into a separate file. This has reduced
the size of ``configobj.py`` by about 40%.
Added the ``unrepr`` mode to reading and writing config files. Thanks to Kevin
Dangoor for this suggestion.
Empty values are now valid syntax. They are read as an empty string ``''``.
(``key =``, or ``key = # comment``.)
``validate`` now honours the order of the configspec.
Added the ``copy`` mode to validate. Thanks to Louis Cordier for this
suggestion.
Fixed bug where files written on windows could be given ``'\r\r\n'`` line
terminators.
Fixed bug where last occurring comment line could be interpreted as the
final comment if the last line isn't terminated.
Fixed bug where nested list values would be flattened when ``write`` is
called. Now sub-lists have a string representation written instead.
Deprecated ``encode`` and ``decode`` methods instead.
You can now pass in a ConfigObj instance as a configspec (remember to read
the configspec file using ``list_values=False``).
Sorted footnotes in the docs.
2006/02/16 - Version 4.2.0
--------------------------
Removed ``BOM_UTF8`` from ``__all__``.
The ``BOM`` attribute has become a boolean. (Defaults to ``False``.) It is
*only* ``True`` for the ``UTF16/UTF8`` encodings.
File like objects no longer need a ``seek`` attribute.
Full unicode support added. New options/attributes ``encoding``,
``default_encoding``.
ConfigObj no longer keeps a reference to file like objects. Instead the
``write`` method takes a file like object as an optional argument. (Which
will be used in preference of the ``filename`` attribute if that exists as
well.)
utf16 files decoded to unicode.
If ``BOM`` is ``True``, but no encoding specified, then the utf8 BOM is
written out at the start of the file. (It will normally only be ``True`` if
the utf8 BOM was found when the file was read.)
Thanks to Aaron Bentley for help and testing on the unicode issues.
File paths are *not* converted to absolute paths, relative paths will
remain relative as the ``filename`` attribute.
Fixed bug where ``final_comment`` wasn't returned if ``write`` is returning
a list of lines.
Deprecated ``istrue``, replaced it with ``as_bool``.
Added ``as_int`` and ``as_float``.
2005/12/14 - Version 4.1.0
--------------------------
Added ``merge``, a recursive update.
Added ``preserve_errors`` to ``validate`` and the ``flatten_errors``
example function.
Thanks to Matthew Brett for suggestions and helping me iron out bugs.
Fixed bug where a config file is *all* comment, the comment will now be
``initial_comment`` rather than ``final_comment``.
Validation no longer done on the 'DEFAULT' section (only in the root level).
This allows interpolation in configspecs.
Also use the new list syntax in validate_ 0.2.1. (For configspecs).
2005/12/02 - Version 4.0.2
--------------------------
Fixed bug in ``create_empty``. Thanks to Paul Jimenez for the report.
2005/11/05 - Version 4.0.1
--------------------------
Fixed bug in ``Section.walk`` when transforming names as well as values.
Added the ``istrue`` method. (Fetches the boolean equivalent of a string
value).
Fixed ``list_values=False`` - they are now only quoted/unquoted if they
are multiline values.
List values are written as ``item, item`` rather than ``item,item``.
2005/10/17 - Version 4.0.0
--------------------------
**ConfigObj 4.0.0 Final**
Fixed bug in ``setdefault``. When creating a new section with setdefault the
reference returned would be to the dictionary passed in *not* to the new
section. Bug fixed and behaviour documented.
Obscure typo/bug fixed in ``write``. Wouldn't have affected anyone though.
2005/09/09 - Version 4.0.0 beta 5
---------------------------------
Removed ``PositionError``.
Allowed quotes around keys as documented.
Fixed bug with commas in comments. (matched as a list value)
2005/09/07 - Version 4.0.0 beta 4
---------------------------------
Fixed bug in ``__delitem__``. Deleting an item no longer deletes the
``inline_comments`` attribute.
Fixed bug in initialising ConfigObj from a ConfigObj.
Changed the mailing list address.
2005/08/28 - Version 4.0.0 beta 3
---------------------------------
Interpolation is switched off before writing out files.
Fixed bug in handling ``StringIO`` instances. (Thanks to report from
Gustavo Niemeyer.)
Moved the doctests from the ``__init__`` method to a separate function.
(For the sake of IDE calltips).
2005/08/25 - Version 4.0.0 beta 2
---------------------------------
Amendments to *validate.py*.
First public release.
2005/08/21 - Version 4.0.0 beta 1
---------------------------------
Reads nested subsections to any depth.
Multiline values.
Simplified options and methods.
New list syntax.
Faster, smaller, and better parser.
Validation greatly improved. Includes:
* type conversion
* default values
* repeated sections
Improved error handling.
Plus lots of other improvements. {sm;:grin:}
2004/05/24 - Version 3.0.0
--------------------------
Several incompatible changes: another major overhaul and change. (Lots of
improvements though).
Added support for standard config files with sections. This has an entirely
new interface: each section is a dictionary of values.
Changed the update method to be called writein: update clashes with a dict
method.
Made various attributes keyword arguments, added several.
Configspecs and orderlists have changed a great deal.
Removed support for adding dictionaries: use update instead.
Now subclasses a new class called caselessDict. This should add various
dictionary methods that could have caused errors before.
It also preserves the original casing of keywords when writing them back out.
Comments are also saved using a ``caselessDict``.
Using a non-string key will now raise a ``TypeError`` rather than converting
the key.
Added an exceptions keyword for *much* better handling of errors.
Made ``creatempty=False`` the default.
Now checks indict *and* any keyword args. Keyword args take precedence over
indict.
``' ', ':', '=', ','`` and ``'\t'`` are now all valid dividers where the
keyword is unquoted.
ConfigObj now does no type checking against configspec when you set items.
delete and add methods removed (they were unnecessary).
Docs rewritten to include all this gumph and more; actually ConfigObj is
*really* easy to use.
Support for stdout was removed.
A few new methods added.
Charmap is now incorporated into ConfigObj.
2004/03/14 - Version 2.0.0 beta
-------------------------------
Re-written it to subclass dict. My first forays into inheritance and operator
overloading.
The config object now behaves like a dictionary.
I've completely broken the interface, but I don't think anyone was really
using it anyway.
This new version is much more 'classy'. {sm;:wink:}
It will also read straight from/to a filename and completely parse a config
file without you *having* to supply a config spec.
Uses listparse, so can handle nested list items as values.
No longer has getval and setval methods: use normal dictionary methods, or add
and delete.
2004/01/29 - Version 1.0.5
--------------------------
Version 1.0.5 has a couple of bugfixes as well as a couple of useful additions
over previous versions.
Since 1.0.0 the buildconfig function has been moved into this distribution,
and the methods reset, verify, getval and setval have been added.
A couple of bugs have been fixed.
Origins
-------
ConfigObj originated in a set of functions for reading config files in the
`atlantibots `_ project. The original
functions were written by Rob McNeur.
----------
Footnotes
=========
.. [#] And if you discover any bugs, let us know. We'll fix them quickly.
.. [#] If you specify a filename that doesn't exist, ConfigObj will assume you
are creating a new one. See the *create_empty* and *file_error* options_.
.. [#] They can be byte strings (*ordinary* strings) or Unicode.
.. [#] Except we don't support the RFC822 style line continuations, nor ':' as
a divider.
.. [#] This is a change in ConfigObj 4.2.0. Note that ConfigObj doesn't call
the seek method of any file like object you pass in. You may want to call
``file_object.seek(0)`` yourself, first.
.. [#] A side effect of this is that it enables you to copy a ConfigObj :
.. raw:: html
{+coloring}
# only copies members
# not attributes/comments
config2 = ConfigObj(config1)
{-coloring}
The order of values and sections will not be preserved, though.
.. [#] Other than lists of strings.
.. [#] The exception is if it detects a ``UTF16`` encoded file which it
must decode before parsing.
.. [#] The method signature shows that this method takes
two arguments. The second is the section to be written. This is because the
``write`` method is called recursively.
.. [#] The dict method doesn't actually use the deepcopy mechanism. This means
if you add nested lists (etc) to your ConfigObj, then the dictionary
returned by dict may contain some references. For all *normal* ConfigObjs
it will return a deepcopy.
.. [#] Passing ``(section, key)`` rather than ``(value, key)`` allows you to
change the value by setting ``section[key] = newval``. It also gives you
access to the *rename* method of the section.
.. [#] Minimum required version of *validate.py* 0.2.0 .
.. note::
Rendering this document with docutils also needs the
textmacros module and the PySrc CSS stuff. See
http://www.voidspace.org.uk/python/firedrop2/textmacros.shtml
.. raw:: html
.. _listquote: http://www.voidspace.org.uk/python/modules.shtml#listquote
.. _Michael Foord: http://www.voidspace.org.uk/python/weblog/index.shtml
.. _Nicola Larosa: http://www.teknico.net
