=========

multidict

=========

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Multidict is dict-like collection of *key-value pairs* where key

might occur more than once in the container.

Introduction

------------

*HTTP Headers* and *URL query string* require specific data structure:

*multidict*. It behaves mostly like a regular ``dict`` but it may have

several *values* for the same *key* and *preserves insertion ordering*.

The *key* is ``str`` (or ``istr`` for case-insensitive dictionaries).

``multidict`` has four multidict classes:

``MultiDict``, ``MultiDictProxy``, ``CIMultiDict``

and ``CIMultiDictProxy``.

Immutable proxies (``MultiDictProxy`` and

``CIMultiDictProxy``) provide a dynamic view for the

proxied multidict, the view reflects underlying collection changes. They

implement the ``collections.abc.Mapping`` interface.

Regular mutable (``MultiDict`` and ``CIMultiDict``) classes

implement ``collections.abc.MutableMapping`` and allows them to change

their own content.

*Case insensitive* (``CIMultiDict`` and

``CIMultiDictProxy``) assume the *keys* are case

insensitive, e.g.::

>>> dct = CIMultiDict(key='val')

>>> 'Key' in dct

True

>>> dct['Key']

'val'

*Keys* should be ``str`` or ``istr`` instances.

The library has optional C Extensions for speed.

License

-------

Apache 2

Library Installation

--------------------

.. code-block:: bash

$ pip install multidict

The library is Python 3 only!

PyPI contains binary wheels for Linux, Windows and MacOS. If you want to install

``multidict`` on another operating system (or *Alpine Linux* inside a Docker) the

tarball will be used to compile the library from source. It requires a C compiler and

Python headers to be installed.

To skip the compilation, please use the `MULTIDICT_NO_EXTENSIONS` environment variable,

e.g.:

.. code-block:: bash

$ MULTIDICT_NO_EXTENSIONS=1 pip install multidict

Please note, the pure Python (uncompiled) version is about 20-50 times slower depending on

the usage scenario!!!

Changelog

---------

See `RTD page <http://multidict.aio-libs.org/en/latest/changes>`_.