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:mod:`configparser` --- Configuration file parser
=================================================
.. module:: configparser
:synopsis: Configuration file parser.
.. moduleauthor:: Ken Manheimer <klm@zope.com>
.. moduleauthor:: Barry Warsaw <bwarsaw@python.org>
.. moduleauthor:: Eric S. Raymond <esr@thyrsus.com>
.. moduleauthor:: Łukasz Langa <lukasz@langa.pl>
.. sectionauthor:: Christopher G. Petrilli <petrilli@amber.org>
.. sectionauthor:: Łukasz Langa <lukasz@langa.pl>
**Source code:** :source:`Lib/configparser.py`
.. index::
pair: .ini; file
pair: configuration; file
single: ini file
single: Windows ini file
--------------
This module provides the :class:`ConfigParser` class which implements a basic
configuration language which provides a structure similar to what's found in
Microsoft Windows INI files. You can use this to write Python programs which
can be customized by end users easily.
.. note::
This library does *not* interpret or write the value-type prefixes used in
the Windows Registry extended version of INI syntax.
.. seealso::
Module :mod:`shlex`
Support for creating Unix shell-like mini-languages which can be used as
an alternate format for application configuration files.
Module :mod:`json`
The json module implements a subset of JavaScript syntax which can also
be used for this purpose.
.. testsetup::
import configparser
Quick Start
-----------
Let's take a very basic configuration file that looks like this:
.. code-block:: ini
[DEFAULT]
ServerAliveInterval = 45
Compression = yes
CompressionLevel = 9
ForwardX11 = yes
[bitbucket.org]
User = hg
[topsecret.server.com]
Port = 50022
ForwardX11 = no
The structure of INI files is described `in the following section
<#supported-ini-file-structure>`_. Essentially, the file
consists of sections, each of which contains keys with values.
:mod:`configparser` classes can read and write such files. Let's start by
creating the above configuration file programmatically.
.. doctest::
>>> import configparser
>>> config = configparser.ConfigParser()
>>> config['DEFAULT'] = {'ServerAliveInterval': '45',
... 'Compression': 'yes',
... 'CompressionLevel': '9'}
>>> config['bitbucket.org'] = {}
>>> config['bitbucket.org']['User'] = 'hg'
>>> config['topsecret.server.com'] = {}
>>> topsecret = config['topsecret.server.com']
>>> topsecret['Port'] = '50022' # mutates the parser
>>> topsecret['ForwardX11'] = 'no' # same here
>>> config['DEFAULT']['ForwardX11'] = 'yes'
>>> with open('example.ini', 'w') as configfile:
... config.write(configfile)
...
As you can see, we can treat a config parser much like a dictionary.
There are differences, `outlined later <#mapping-protocol-access>`_, but
the behavior is very close to what you would expect from a dictionary.
Now that we have created and saved a configuration file, let's read it
back and explore the data it holds.
.. doctest::
>>> config = configparser.ConfigParser()
>>> config.sections()
[]
>>> config.read('example.ini')
['example.ini']
>>> config.sections()
['bitbucket.org', 'topsecret.server.com']
>>> 'bitbucket.org' in config
True
>>> 'bytebong.com' in config
False
>>> config['bitbucket.org']['User']
'hg'
>>> config['DEFAULT']['Compression']
'yes'
>>> topsecret = config['topsecret.server.com']
>>> topsecret['ForwardX11']
'no'
>>> topsecret['Port']
'50022'
>>> for key in config['bitbucket.org']: # doctest: +SKIP
... print(key)
user
compressionlevel
serveraliveinterval
compression
forwardx11
>>> config['bitbucket.org']['ForwardX11']
'yes'
As we can see above, the API is pretty straightforward. The only bit of magic
involves the ``DEFAULT`` section which provides default values for all other
sections [1]_. Note also that keys in sections are
case-insensitive and stored in lowercase [1]_.
Supported Datatypes
-------------------
Config parsers do not guess datatypes of values in configuration files, always
storing them internally as strings. This means that if you need other
datatypes, you should convert on your own:
.. doctest::
>>> int(topsecret['Port'])
50022
>>> float(topsecret['CompressionLevel'])
9.0
Since this task is so common, config parsers provide a range of handy getter
methods to handle integers, floats and booleans. The last one is the most
interesting because simply passing the value to ``bool()`` would do no good
since ``bool('False')`` is still ``True``. This is why config parsers also
provide :meth:`~ConfigParser.getboolean`. This method is case-insensitive and
recognizes Boolean values from ``'yes'``/``'no'``, ``'on'``/``'off'``,
``'true'``/``'false'`` and ``'1'``/``'0'`` [1]_. For example:
.. doctest::
>>> topsecret.getboolean('ForwardX11')
False
>>> config['bitbucket.org'].getboolean('ForwardX11')
True
>>> config.getboolean('bitbucket.org', 'Compression')
True
Apart from :meth:`~ConfigParser.getboolean`, config parsers also
provide equivalent :meth:`~ConfigParser.getint` and
:meth:`~ConfigParser.getfloat` methods. You can register your own
converters and customize the provided ones. [1]_
Fallback Values
---------------
As with a dictionary, you can use a section's :meth:`get` method to
provide fallback values:
.. doctest::
>>> topsecret.get('Port')
'50022'
>>> topsecret.get('CompressionLevel')
'9'
>>> topsecret.get('Cipher')
>>> topsecret.get('Cipher', '3des-cbc')
'3des-cbc'
Please note that default values have precedence over fallback values.
For instance, in our example the ``'CompressionLevel'`` key was
specified only in the ``'DEFAULT'`` section. If we try to get it from
the section ``'topsecret.server.com'``, we will always get the default,
even if we specify a fallback:
.. doctest::
>>> topsecret.get('CompressionLevel', '3')
'9'
One more thing to be aware of is that the parser-level :meth:`get` method
provides a custom, more complex interface, maintained for backwards
compatibility. When using this method, a fallback value can be provided via
the ``fallback`` keyword-only argument:
.. doctest::
>>> config.get('bitbucket.org', 'monster',
... fallback='No such things as monsters')
'No such things as monsters'
The same ``fallback`` argument can be used with the
:meth:`~ConfigParser.getint`, :meth:`~ConfigParser.getfloat` and
:meth:`~ConfigParser.getboolean` methods, for example:
.. doctest::
>>> 'BatchMode' in topsecret
False
>>> topsecret.getboolean('BatchMode', fallback=True)
True
>>> config['DEFAULT']['BatchMode'] = 'no'
>>> topsecret.getboolean('BatchMode', fallback=True)
False
Supported INI File Structure
----------------------------
A configuration file consists of sections, each led by a ``[section]`` header,
followed by key/value entries separated by a specific string (``=`` or ``:`` by
default [1]_). By default, section names are case sensitive but keys are not
[1]_. Leading and trailing whitespace is removed from keys and values.
Values can be omitted, in which case the key/value delimiter may also be left
out. Values can also span multiple lines, as long as they are indented deeper
than the first line of the value. Depending on the parser's mode, blank lines
may be treated as parts of multiline values or ignored.
Configuration files may include comments, prefixed by specific
characters (``#`` and ``;`` by default [1]_). Comments may appear on
their own on an otherwise empty line, possibly indented. [1]_
For example:
.. code-block:: ini
[Simple Values]
key=value
spaces in keys=allowed
spaces in values=allowed as well
spaces around the delimiter = obviously
you can also use : to delimit keys from values
[All Values Are Strings]
values like this: 1000000
or this: 3.14159265359
are they treated as numbers? : no
integers, floats and booleans are held as: strings
can use the API to get converted values directly: true
[Multiline Values]
chorus: I'm a lumberjack, and I'm okay
I sleep all night and I work all day
[No Values]
key_without_value
empty string value here =
[You can use comments]
# like this
; or this
# By default only in an empty line.
# Inline comments can be harmful because they prevent users
# from using the delimiting characters as parts of values.
# That being said, this can be customized.
[Sections Can Be Indented]
can_values_be_as_well = True
does_that_mean_anything_special = False
purpose = formatting for readability
multiline_values = are
handled just fine as
long as they are indented
deeper than the first line
of a value
# Did I mention we can indent comments, too?
Interpolation of values
-----------------------
On top of the core functionality, :class:`ConfigParser` supports
interpolation. This means values can be preprocessed before returning them
from ``get()`` calls.
.. class:: BasicInterpolation()
The default implementation used by :class:`ConfigParser`. It enables
values to contain format strings which refer to other values in the same
section, or values in the special default section [1]_. Additional default
values can be provided on initialization.
For example:
.. code-block:: ini
[Paths]
home_dir: /Users
my_dir: %(home_dir)s/lumberjack
my_pictures: %(my_dir)s/Pictures
In the example above, :class:`ConfigParser` with *interpolation* set to
``BasicInterpolation()`` would resolve ``%(home_dir)s`` to the value of
``home_dir`` (``/Users`` in this case). ``%(my_dir)s`` in effect would
resolve to ``/Users/lumberjack``. All interpolations are done on demand so
keys used in the chain of references do not have to be specified in any
specific order in the configuration file.
With ``interpolation`` set to ``None``, the parser would simply return
``%(my_dir)s/Pictures`` as the value of ``my_pictures`` and
``%(home_dir)s/lumberjack`` as the value of ``my_dir``.
.. class:: ExtendedInterpolation()
An alternative handler for interpolation which implements a more advanced
syntax, used for instance in ``zc.buildout``. Extended interpolation is
using ``${section:option}`` to denote a value from a foreign section.
Interpolation can span multiple levels. For convenience, if the
``section:`` part is omitted, interpolation defaults to the current section
(and possibly the default values from the special section).
For example, the configuration specified above with basic interpolation,
would look like this with extended interpolation:
.. code-block:: ini
[Paths]
home_dir: /Users
my_dir: ${home_dir}/lumberjack
my_pictures: ${my_dir}/Pictures
Values from other sections can be fetched as well:
.. code-block:: ini
[Common]
home_dir: /Users
library_dir: /Library
system_dir: /System
macports_dir: /opt/local
[Frameworks]
Python: 3.2
path: ${Common:system_dir}/Library/Frameworks/
[Arthur]
nickname: Two Sheds
last_name: Jackson
my_dir: ${Common:home_dir}/twosheds
my_pictures: ${my_dir}/Pictures
python_dir: ${Frameworks:path}/Python/Versions/${Frameworks:Python}
Mapping Protocol Access
-----------------------
.. versionadded:: 3.2
Mapping protocol access is a generic name for functionality that enables using
custom objects as if they were dictionaries. In case of :mod:`configparser`,
the mapping interface implementation is using the
``parser['section']['option']`` notation.
``parser['section']`` in particular returns a proxy for the section's data in
the parser. This means that the values are not copied but they are taken from
the original parser on demand. What's even more important is that when values
are changed on a section proxy, they are actually mutated in the original
parser.
:mod:`configparser` objects behave as close to actual dictionaries as possible.
The mapping interface is complete and adheres to the
:class:`~collections.abc.MutableMapping` ABC.
However, there are a few differences that should be taken into account:
* By default, all keys in sections are accessible in a case-insensitive manner
[1]_. E.g. ``for option in parser["section"]`` yields only ``optionxform``'ed
option key names. This means lowercased keys by default. At the same time,
for a section that holds the key ``'a'``, both expressions return ``True``::
"a" in parser["section"]
"A" in parser["section"]
* All sections include ``DEFAULTSECT`` values as well which means that
``.clear()`` on a section may not leave the section visibly empty. This is
because default values cannot be deleted from the section (because technically
they are not there). If they are overridden in the section, deleting causes
the default value to be visible again. Trying to delete a default value
causes a ``KeyError``.
* ``DEFAULTSECT`` cannot be removed from the parser:
* trying to delete it raises ``ValueError``,
* ``parser.clear()`` leaves it intact,
* ``parser.popitem()`` never returns it.
* ``parser.get(section, option, **kwargs)`` - the second argument is **not**
a fallback value. Note however that the section-level ``get()`` methods are
compatible both with the mapping protocol and the classic configparser API.
* ``parser.items()`` is compatible with the mapping protocol (returns a list of
*section_name*, *section_proxy* pairs including the DEFAULTSECT). However,
this method can also be invoked with arguments: ``parser.items(section, raw,
vars)``. The latter call returns a list of *option*, *value* pairs for
a specified ``section``, with all interpolations expanded (unless
``raw=True`` is provided).
The mapping protocol is implemented on top of the existing legacy API so that
subclasses overriding the original interface still should have mappings working
as expected.
Customizing Parser Behaviour
----------------------------
There are nearly as many INI format variants as there are applications using it.
:mod:`configparser` goes a long way to provide support for the largest sensible
set of INI styles available. The default functionality is mainly dictated by
historical background and it's very likely that you will want to customize some
of the features.
The most common way to change the way a specific config parser works is to use
the :meth:`__init__` options:
* *defaults*, default value: ``None``
This option accepts a dictionary of key-value pairs which will be initially
put in the ``DEFAULT`` section. This makes for an elegant way to support
concise configuration files that don't specify values which are the same as
the documented default.
Hint: if you want to specify default values for a specific section, use
:meth:`read_dict` before you read the actual file.
* *dict_type*, default value: :class:`dict`
This option has a major impact on how the mapping protocol will behave and how
the written configuration files look. With the standard dictionary, every
section is stored in the order they were added to the parser. Same goes for
options within sections.
An alternative dictionary type can be used for example to sort sections and
options on write-back.
Please note: there are ways to add a set of key-value pairs in a single
operation. When you use a regular dictionary in those operations, the order
of the keys will be ordered. For example:
.. doctest::
>>> parser = configparser.ConfigParser()
>>> parser.read_dict({'section1': {'key1': 'value1',
... 'key2': 'value2',
... 'key3': 'value3'},
... 'section2': {'keyA': 'valueA',
... 'keyB': 'valueB',
... 'keyC': 'valueC'},
... 'section3': {'foo': 'x',
... 'bar': 'y',
... 'baz': 'z'}
... })
>>> parser.sections() # doctest: +SKIP
['section1', 'section2', 'section3']
>>> [option for option in parser['section3']] # doctest: +SKIP
['foo', 'bar', 'baz']
* *allow_no_value*, default value: ``False``
Some configuration files are known to include settings without values, but
which otherwise conform to the syntax supported by :mod:`configparser`. The
*allow_no_value* parameter to the constructor can be used to
indicate that such values should be accepted:
.. doctest::
>>> import configparser
>>> sample_config = """
... [mysqld]
... user = mysql
... pid-file = /var/run/mysqld/mysqld.pid
... skip-external-locking
... old_passwords = 1
... skip-bdb
... # we don't need ACID today
... skip-innodb
... """
>>> config = configparser.ConfigParser(allow_no_value=True)
>>> config.read_string(sample_config)
>>> # Settings with values are treated as before:
>>> config["mysqld"]["user"]
'mysql'
>>> # Settings without values provide None:
>>> config["mysqld"]["skip-bdb"]
>>> # Settings which aren't specified still raise an error:
>>> config["mysqld"]["does-not-exist"]
Traceback (most recent call last):
...
KeyError: 'does-not-exist'
* *delimiters*, default value: ``('=', ':')``
Delimiters are substrings that delimit keys from values within a section.
The first occurrence of a delimiting substring on a line is considered
a delimiter. This means values (but not keys) can contain the delimiters.
See also the *space_around_delimiters* argument to
:meth:`ConfigParser.write`.
* *comment_prefixes*, default value: ``('#', ';')``
* *inline_comment_prefixes*, default value: ``None``
Comment prefixes are strings that indicate the start of a valid comment within
a config file. *comment_prefixes* are used only on otherwise empty lines
(optionally indented) whereas *inline_comment_prefixes* can be used after
every valid value (e.g. section names, options and empty lines as well). By
default inline comments are disabled and ``'#'`` and ``';'`` are used as
prefixes for whole line comments.
.. versionchanged:: 3.2
In previous versions of :mod:`configparser` behaviour matched
``comment_prefixes=('#',';')`` and ``inline_comment_prefixes=(';',)``.
Please note that config parsers don't support escaping of comment prefixes so
using *inline_comment_prefixes* may prevent users from specifying option
values with characters used as comment prefixes. When in doubt, avoid
setting *inline_comment_prefixes*. In any circumstances, the only way of
storing comment prefix characters at the beginning of a line in multiline
values is to interpolate the prefix, for example::
>>> from configparser import ConfigParser, ExtendedInterpolation
>>> parser = ConfigParser(interpolation=ExtendedInterpolation())
>>> # the default BasicInterpolation could be used as well
>>> parser.read_string("""
... [DEFAULT]
... hash = #
...
... [hashes]
... shebang =
... ${hash}!/usr/bin/env python
... ${hash} -*- coding: utf-8 -*-
...
... extensions =
... enabled_extension
... another_extension
... #disabled_by_comment
... yet_another_extension
...
... interpolation not necessary = if # is not at line start
... even in multiline values = line #1
... line #2
... line #3
... """)
>>> print(parser['hashes']['shebang'])
<BLANKLINE>
#!/usr/bin/env python
# -*- coding: utf-8 -*-
>>> print(parser['hashes']['extensions'])
<BLANKLINE>
enabled_extension
another_extension
yet_another_extension
>>> print(parser['hashes']['interpolation not necessary'])
if # is not at line start
>>> print(parser['hashes']['even in multiline values'])
line #1
line #2
line #3
* *strict*, default value: ``True``
When set to ``True``, the parser will not allow for any section or option
duplicates while reading from a single source (using :meth:`read_file`,
:meth:`read_string` or :meth:`read_dict`). It is recommended to use strict
parsers in new applications.
.. versionchanged:: 3.2
In previous versions of :mod:`configparser` behaviour matched
``strict=False``.
* *empty_lines_in_values*, default value: ``True``
In config parsers, values can span multiple lines as long as they are
indented more than the key that holds them. By default parsers also let
empty lines to be parts of values. At the same time, keys can be arbitrarily
indented themselves to improve readability. In consequence, when
configuration files get big and complex, it is easy for the user to lose
track of the file structure. Take for instance:
.. code-block:: ini
[Section]
key = multiline
value with a gotcha
this = is still a part of the multiline value of 'key'
This can be especially problematic for the user to see if she's using a
proportional font to edit the file. That is why when your application does
not need values with empty lines, you should consider disallowing them. This
will make empty lines split keys every time. In the example above, it would
produce two keys, ``key`` and ``this``.
* *default_section*, default value: ``configparser.DEFAULTSECT`` (that is:
``"DEFAULT"``)
The convention of allowing a special section of default values for other
sections or interpolation purposes is a powerful concept of this library,
letting users create complex declarative configurations. This section is
normally called ``"DEFAULT"`` but this can be customized to point to any
other valid section name. Some typical values include: ``"general"`` or
``"common"``. The name provided is used for recognizing default sections
when reading from any source and is used when writing configuration back to
a file. Its current value can be retrieved using the
``parser_instance.default_section`` attribute and may be modified at runtime
(i.e. to convert files from one format to another).
* *interpolation*, default value: ``configparser.BasicInterpolation``
Interpolation behaviour may be customized by providing a custom handler
through the *interpolation* argument. ``None`` can be used to turn off
interpolation completely, ``ExtendedInterpolation()`` provides a more
advanced variant inspired by ``zc.buildout``. More on the subject in the
`dedicated documentation section <#interpolation-of-values>`_.
:class:`RawConfigParser` has a default value of ``None``.
* *converters*, default value: not set
Config parsers provide option value getters that perform type conversion. By
default :meth:`~ConfigParser.getint`, :meth:`~ConfigParser.getfloat`, and
:meth:`~ConfigParser.getboolean` are implemented. Should other getters be
desirable, users may define them in a subclass or pass a dictionary where each
key is a name of the converter and each value is a callable implementing said
conversion. For instance, passing ``{'decimal': decimal.Decimal}`` would add
:meth:`getdecimal` on both the parser object and all section proxies. In
other words, it will be possible to write both
``parser_instance.getdecimal('section', 'key', fallback=0)`` and
``parser_instance['section'].getdecimal('key', 0)``.
If the converter needs to access the state of the parser, it can be
implemented as a method on a config parser subclass. If the name of this
method starts with ``get``, it will be available on all section proxies, in
the dict-compatible form (see the ``getdecimal()`` example above).
More advanced customization may be achieved by overriding default values of
these parser attributes. The defaults are defined on the classes, so they may
be overridden by subclasses or by attribute assignment.
.. attribute:: BOOLEAN_STATES
By default when using :meth:`~ConfigParser.getboolean`, config parsers
consider the following values ``True``: ``'1'``, ``'yes'``, ``'true'``,
``'on'`` and the following values ``False``: ``'0'``, ``'no'``, ``'false'``,
``'off'``. You can override this by specifying a custom dictionary of strings
and their Boolean outcomes. For example:
.. doctest::
>>> custom = configparser.ConfigParser()
>>> custom['section1'] = {'funky': 'nope'}
>>> custom['section1'].getboolean('funky')
Traceback (most recent call last):
...
ValueError: Not a boolean: nope
>>> custom.BOOLEAN_STATES = {'sure': True, 'nope': False}
>>> custom['section1'].getboolean('funky')
False
Other typical Boolean pairs include ``accept``/``reject`` or
``enabled``/``disabled``.
.. method:: optionxform(option)
This method transforms option names on every read, get, or set
operation. The default converts the name to lowercase. This also
means that when a configuration file gets written, all keys will be
lowercase. Override this method if that's unsuitable.
For example:
.. doctest::
>>> config = """
... [Section1]
... Key = Value
...
... [Section2]
... AnotherKey = Value
... """
>>> typical = configparser.ConfigParser()
>>> typical.read_string(config)
>>> list(typical['Section1'].keys())
['key']
>>> list(typical['Section2'].keys())
['anotherkey']
>>> custom = configparser.RawConfigParser()
>>> custom.optionxform = lambda option: option
>>> custom.read_string(config)
>>> list(custom['Section1'].keys())
['Key']
>>> list(custom['Section2'].keys())
['AnotherKey']
.. attribute:: SECTCRE
A compiled regular expression used to parse section headers. The default
matches ``[section]`` to the name ``"section"``. Whitespace is considered
part of the section name, thus ``[ larch ]`` will be read as a section of
name ``" larch "``. Override this attribute if that's unsuitable. For
example:
.. doctest::
>>> import re
>>> config = """
... [Section 1]
... option = value
...
... [ Section 2 ]
... another = val
... """
>>> typical = configparser.ConfigParser()
>>> typical.read_string(config)
>>> typical.sections()
['Section 1', ' Section 2 ']
>>> custom = configparser.ConfigParser()
>>> custom.SECTCRE = re.compile(r"\[ *(?P<header>[^]]+?) *\]")
>>> custom.read_string(config)
>>> custom.sections()
['Section 1', 'Section 2']
.. note::
While ConfigParser objects also use an ``OPTCRE`` attribute for recognizing
option lines, it's not recommended to override it because that would
interfere with constructor options *allow_no_value* and *delimiters*.
Legacy API Examples
-------------------
Mainly because of backwards compatibility concerns, :mod:`configparser`
provides also a legacy API with explicit ``get``/``set`` methods. While there
are valid use cases for the methods outlined below, mapping protocol access is
preferred for new projects. The legacy API is at times more advanced,
low-level and downright counterintuitive.
An example of writing to a configuration file::
import configparser
config = configparser.RawConfigParser()
# Please note that using RawConfigParser's set functions, you can assign
# non-string values to keys internally, but will receive an error when
# attempting to write to a file or when you get it in non-raw mode. Setting
# values using the mapping protocol or ConfigParser's set() does not allow
# such assignments to take place.
config.add_section('Section1')
config.set('Section1', 'an_int', '15')
config.set('Section1', 'a_bool', 'true')
config.set('Section1', 'a_float', '3.1415')
config.set('Section1', 'baz', 'fun')
config.set('Section1', 'bar', 'Python')
config.set('Section1', 'foo', '%(bar)s is %(baz)s!')
# Writing our configuration file to 'example.cfg'
with open('example.cfg', 'w') as configfile:
config.write(configfile)
An example of reading the configuration file again::
import configparser
config = configparser.RawConfigParser()
config.read('example.cfg')
# getfloat() raises an exception if the value is not a float
# getint() and getboolean() also do this for their respective types
a_float = config.getfloat('Section1', 'a_float')
an_int = config.getint('Section1', 'an_int')
print(a_float + an_int)
# Notice that the next output does not interpolate '%(bar)s' or '%(baz)s'.
# This is because we are using a RawConfigParser().
if config.getboolean('Section1', 'a_bool'):
print(config.get('Section1', 'foo'))
To get interpolation, use :class:`ConfigParser`::
import configparser
cfg = configparser.ConfigParser()
cfg.read('example.cfg')
# Set the optional *raw* argument of get() to True if you wish to disable
# interpolation in a single get operation.
print(cfg.get('Section1', 'foo', raw=False)) # -> "Python is fun!"
print(cfg.get('Section1', 'foo', raw=True)) # -> "%(bar)s is %(baz)s!"
# The optional *vars* argument is a dict with members that will take
# precedence in interpolation.
print(cfg.get('Section1', 'foo', vars={'bar': 'Documentation',
'baz': 'evil'}))
# The optional *fallback* argument can be used to provide a fallback value
print(cfg.get('Section1', 'foo'))
# -> "Python is fun!"
print(cfg.get('Section1', 'foo', fallback='Monty is not.'))
# -> "Python is fun!"
print(cfg.get('Section1', 'monster', fallback='No such things as monsters.'))
# -> "No such things as monsters."
# A bare print(cfg.get('Section1', 'monster')) would raise NoOptionError
# but we can also use:
print(cfg.get('Section1', 'monster', fallback=None))
# -> None
Default values are available in both types of ConfigParsers. They are used in
interpolation if an option used is not defined elsewhere. ::
import configparser
# New instance with 'bar' and 'baz' defaulting to 'Life' and 'hard' each
config = configparser.ConfigParser({'bar': 'Life', 'baz': 'hard'})
config.read('example.cfg')
print(config.get('Section1', 'foo')) # -> "Python is fun!"
config.remove_option('Section1', 'bar')
config.remove_option('Section1', 'baz')
print(config.get('Section1', 'foo')) # -> "Life is hard!"
.. _configparser-objects:
ConfigParser Objects
--------------------
.. class:: ConfigParser(defaults=None, dict_type=dict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=('#', ';'), inline_comment_prefixes=None, strict=True, empty_lines_in_values=True, default_section=configparser.DEFAULTSECT, interpolation=BasicInterpolation(), converters={})
The main configuration parser. When *defaults* is given, it is initialized
into the dictionary of intrinsic defaults. When *dict_type* is given, it
will be used to create the dictionary objects for the list of sections, for
the options within a section, and for the default values.
When *delimiters* is given, it is used as the set of substrings that
divide keys from values. When *comment_prefixes* is given, it will be used
as the set of substrings that prefix comments in otherwise empty lines.
Comments can be indented. When *inline_comment_prefixes* is given, it will
be used as the set of substrings that prefix comments in non-empty lines.
When *strict* is ``True`` (the default), the parser won't allow for
any section or option duplicates while reading from a single source (file,
string or dictionary), raising :exc:`DuplicateSectionError` or
:exc:`DuplicateOptionError`. When *empty_lines_in_values* is ``False``
(default: ``True``), each empty line marks the end of an option. Otherwise,
internal empty lines of a multiline option are kept as part of the value.
When *allow_no_value* is ``True`` (default: ``False``), options without
values are accepted; the value held for these is ``None`` and they are
serialized without the trailing delimiter.
When *default_section* is given, it specifies the name for the special
section holding default values for other sections and interpolation purposes
(normally named ``"DEFAULT"``). This value can be retrieved and changed on
runtime using the ``default_section`` instance attribute.
Interpolation behaviour may be customized by providing a custom handler
through the *interpolation* argument. ``None`` can be used to turn off
interpolation completely, ``ExtendedInterpolation()`` provides a more
advanced variant inspired by ``zc.buildout``. More on the subject in the
`dedicated documentation section <#interpolation-of-values>`_.
All option names used in interpolation will be passed through the
:meth:`optionxform` method just like any other option name reference. For
example, using the default implementation of :meth:`optionxform` (which
converts option names to lower case), the values ``foo %(bar)s`` and ``foo
%(BAR)s`` are equivalent.
When *converters* is given, it should be a dictionary where each key
represents the name of a type converter and each value is a callable
implementing the conversion from string to the desired datatype. Every
converter gets its own corresponding :meth:`get*()` method on the parser
object and section proxies.
.. versionchanged:: 3.1
The default *dict_type* is :class:`collections.OrderedDict`.
.. versionchanged:: 3.2
*allow_no_value*, *delimiters*, *comment_prefixes*, *strict*,
*empty_lines_in_values*, *default_section* and *interpolation* were
added.
.. versionchanged:: 3.5
The *converters* argument was added.
.. versionchanged:: 3.7
The *defaults* argument is read with :meth:`read_dict()`,
providing consistent behavior across the parser: non-string
keys and values are implicitly converted to strings.
.. versionchanged:: 3.7
The default *dict_type* is :class:`dict`, since it now preserves
insertion order.
.. method:: defaults()
Return a dictionary containing the instance-wide defaults.
.. method:: sections()
Return a list of the sections available; the *default section* is not
included in the list.
.. method:: add_section(section)
Add a section named *section* to the instance. If a section by the given
name already exists, :exc:`DuplicateSectionError` is raised. If the
*default section* name is passed, :exc:`ValueError` is raised. The name
of the section must be a string; if not, :exc:`TypeError` is raised.
.. versionchanged:: 3.2
Non-string section names raise :exc:`TypeError`.
.. method:: has_section(section)
Indicates whether the named *section* is present in the configuration.
The *default section* is not acknowledged.
.. method:: options(section)
Return a list of options available in the specified *section*.
.. method:: has_option(section, option)
If the given *section* exists, and contains the given *option*, return
:const:`True`; otherwise return :const:`False`. If the specified
*section* is :const:`None` or an empty string, DEFAULT is assumed.
.. method:: read(filenames, encoding=None)
Attempt to read and parse an iterable of filenames, returning a list of
filenames which were successfully parsed.
If *filenames* is a string, a :class:`bytes` object or a
:term:`path-like object`, it is treated as
a single filename. If a file named in *filenames* cannot be opened, that
file will be ignored. This is designed so that you can specify an
iterable of potential configuration file locations (for example, the
current directory, the user's home directory, and some system-wide
directory), and all existing configuration files in the iterable will be
read.
If none of the named files exist, the :class:`ConfigParser`
instance will contain an empty dataset. An application which requires
initial values to be loaded from a file should load the required file or
files using :meth:`read_file` before calling :meth:`read` for any
optional files::
import configparser, os
config = configparser.ConfigParser()
config.read_file(open('defaults.cfg'))
config.read(['site.cfg', os.path.expanduser('~/.myapp.cfg')],
encoding='cp1250')
.. versionadded:: 3.2
The *encoding* parameter. Previously, all files were read using the
default encoding for :func:`open`.
.. versionadded:: 3.6.1
The *filenames* parameter accepts a :term:`path-like object`.
.. versionadded:: 3.7
The *filenames* parameter accepts a :class:`bytes` object.
.. method:: read_file(f, source=None)
Read and parse configuration data from *f* which must be an iterable
yielding Unicode strings (for example files opened in text mode).
Optional argument *source* specifies the name of the file being read. If
not given and *f* has a :attr:`name` attribute, that is used for
*source*; the default is ``'<???>'``.
.. versionadded:: 3.2
Replaces :meth:`readfp`.
.. method:: read_string(string, source='<string>')
Parse configuration data from a string.
Optional argument *source* specifies a context-specific name of the
string passed. If not given, ``'<string>'`` is used. This should
commonly be a filesystem path or a URL.
.. versionadded:: 3.2
.. method:: read_dict(dictionary, source='<dict>')
Load configuration from any object that provides a dict-like ``items()``
method. Keys are section names, values are dictionaries with keys and
values that should be present in the section. If the used dictionary
type preserves order, sections and their keys will be added in order.
Values are automatically converted to strings.
Optional argument *source* specifies a context-specific name of the
dictionary passed. If not given, ``<dict>`` is used.
This method can be used to copy state between parsers.
.. versionadded:: 3.2
.. method:: get(section, option, *, raw=False, vars=None[, fallback])
Get an *option* value for the named *section*. If *vars* is provided, it
must be a dictionary. The *option* is looked up in *vars* (if provided),
*section*, and in *DEFAULTSECT* in that order. If the key is not found
and *fallback* is provided, it is used as a fallback value. ``None`` can
be provided as a *fallback* value.
All the ``'%'`` interpolations are expanded in the return values, unless
the *raw* argument is true. Values for interpolation keys are looked up
in the same manner as the option.
.. versionchanged:: 3.2
Arguments *raw*, *vars* and *fallback* are keyword only to protect
users from trying to use the third argument as the *fallback* fallback
(especially when using the mapping protocol).
.. method:: getint(section, option, *, raw=False, vars=None[, fallback])
A convenience method which coerces the *option* in the specified *section*
to an integer. See :meth:`get` for explanation of *raw*, *vars* and
*fallback*.
.. method:: getfloat(section, option, *, raw=False, vars=None[, fallback])
A convenience method which coerces the *option* in the specified *section*
to a floating point number. See :meth:`get` for explanation of *raw*,
*vars* and *fallback*.
.. method:: getboolean(section, option, *, raw=False, vars=None[, fallback])
A convenience method which coerces the *option* in the specified *section*
to a Boolean value. Note that the accepted values for the option are
``'1'``, ``'yes'``, ``'true'``, and ``'on'``, which cause this method to
return ``True``, and ``'0'``, ``'no'``, ``'false'``, and ``'off'``, which
cause it to return ``False``. These string values are checked in a
case-insensitive manner. Any other value will cause it to raise
:exc:`ValueError`. See :meth:`get` for explanation of *raw*, *vars* and
*fallback*.
.. method:: items(raw=False, vars=None)
items(section, raw=False, vars=None)
When *section* is not given, return a list of *section_name*,
*section_proxy* pairs, including DEFAULTSECT.
Otherwise, return a list of *name*, *value* pairs for the options in the
given *section*. Optional arguments have the same meaning as for the
:meth:`get` method.
.. versionchanged:: 3.8
Items present in *vars* no longer appear in the result. The previous
behaviour mixed actual parser options with variables provided for
interpolation.
.. method:: set(section, option, value)
If the given section exists, set the given option to the specified value;
otherwise raise :exc:`NoSectionError`. *option* and *value* must be
strings; if not, :exc:`TypeError` is raised.
.. method:: write(fileobject, space_around_delimiters=True)
Write a representation of the configuration to the specified :term:`file
object`, which must be opened in text mode (accepting strings). This
representation can be parsed by a future :meth:`read` call. If
*space_around_delimiters* is true, delimiters between
keys and values are surrounded by spaces.
.. method:: remove_option(section, option)
Remove the specified *option* from the specified *section*. If the
section does not exist, raise :exc:`NoSectionError`. If the option
existed to be removed, return :const:`True`; otherwise return
:const:`False`.
.. method:: remove_section(section)
Remove the specified *section* from the configuration. If the section in
fact existed, return ``True``. Otherwise return ``False``.
.. method:: optionxform(option)
Transforms the option name *option* as found in an input file or as passed
in by client code to the form that should be used in the internal
structures. The default implementation returns a lower-case version of
*option*; subclasses may override this or client code can set an attribute
of this name on instances to affect this behavior.
You don't need to subclass the parser to use this method, you can also
set it on an instance, to a function that takes a string argument and
returns a string. Setting it to ``str``, for example, would make option
names case sensitive::
cfgparser = ConfigParser()
cfgparser.optionxform = str
Note that when reading configuration files, whitespace around the option
names is stripped before :meth:`optionxform` is called.
.. method:: readfp(fp, filename=None)
.. deprecated:: 3.2
Use :meth:`read_file` instead.
.. versionchanged:: 3.2
:meth:`readfp` now iterates on *fp* instead of calling ``fp.readline()``.
For existing code calling :meth:`readfp` with arguments which don't
support iteration, the following generator may be used as a wrapper
around the file-like object::
def readline_generator(fp):
line = fp.readline()
while line:
yield line
line = fp.readline()
Instead of ``parser.readfp(fp)`` use
``parser.read_file(readline_generator(fp))``.
.. data:: MAX_INTERPOLATION_DEPTH
The maximum depth for recursive interpolation for :meth:`get` when the *raw*
parameter is false. This is relevant only when the default *interpolation*
is used.
.. _rawconfigparser-objects:
RawConfigParser Objects
-----------------------
.. class:: RawConfigParser(defaults=None, dict_type=dict, \
allow_no_value=False, *, delimiters=('=', ':'), \
comment_prefixes=('#', ';'), \
inline_comment_prefixes=None, strict=True, \
empty_lines_in_values=True, \
default_section=configparser.DEFAULTSECT[, \
interpolation])
Legacy variant of the :class:`ConfigParser`. It has interpolation
disabled by default and allows for non-string section names, option
names, and values via its unsafe ``add_section`` and ``set`` methods,
as well as the legacy ``defaults=`` keyword argument handling.
.. versionchanged:: 3.7
The default *dict_type* is :class:`dict`, since it now preserves
insertion order.
.. note::
Consider using :class:`ConfigParser` instead which checks types of
the values to be stored internally. If you don't want interpolation, you
can use ``ConfigParser(interpolation=None)``.
.. method:: add_section(section)
Add a section named *section* to the instance. If a section by the given
name already exists, :exc:`DuplicateSectionError` is raised. If the
*default section* name is passed, :exc:`ValueError` is raised.
Type of *section* is not checked which lets users create non-string named
sections. This behaviour is unsupported and may cause internal errors.
.. method:: set(section, option, value)
If the given section exists, set the given option to the specified value;
otherwise raise :exc:`NoSectionError`. While it is possible to use
:class:`RawConfigParser` (or :class:`ConfigParser` with *raw* parameters
set to true) for *internal* storage of non-string values, full
functionality (including interpolation and output to files) can only be
achieved using string values.
This method lets users assign non-string values to keys internally. This
behaviour is unsupported and will cause errors when attempting to write
to a file or get it in non-raw mode. **Use the mapping protocol API**
which does not allow such assignments to take place.
Exceptions
----------
.. exception:: Error
Base class for all other :mod:`configparser` exceptions.
.. exception:: NoSectionError
Exception raised when a specified section is not found.
.. exception:: DuplicateSectionError
Exception raised if :meth:`add_section` is called with the name of a section
that is already present or in strict parsers when a section if found more
than once in a single input file, string or dictionary.
.. versionadded:: 3.2
Optional ``source`` and ``lineno`` attributes and arguments to
:meth:`__init__` were added.
.. exception:: DuplicateOptionError
Exception raised by strict parsers if a single option appears twice during
reading from a single file, string or dictionary. This catches misspellings
and case sensitivity-related errors, e.g. a dictionary may have two keys
representing the same case-insensitive configuration key.
.. exception:: NoOptionError
Exception raised when a specified option is not found in the specified
section.
.. exception:: InterpolationError
Base class for exceptions raised when problems occur performing string
interpolation.
.. exception:: InterpolationDepthError
Exception raised when string interpolation cannot be completed because the
number of iterations exceeds :const:`MAX_INTERPOLATION_DEPTH`. Subclass of
:exc:`InterpolationError`.
.. exception:: InterpolationMissingOptionError
Exception raised when an option referenced from a value does not exist.
Subclass of :exc:`InterpolationError`.
.. exception:: InterpolationSyntaxError
Exception raised when the source text into which substitutions are made does
not conform to the required syntax. Subclass of :exc:`InterpolationError`.
.. exception:: MissingSectionHeaderError
Exception raised when attempting to parse a file which has no section
headers.
.. exception:: ParsingError
Exception raised when errors occur attempting to parse a file.
.. versionchanged:: 3.2
The ``filename`` attribute and :meth:`__init__` argument were renamed to
``source`` for consistency.
.. rubric:: Footnotes
.. [1] Config parsers allow for heavy customization. If you are interested in
changing the behaviour outlined by the footnote reference, consult the
`Customizing Parser Behaviour`_ section.
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