`psycopg2.extras` -- Miscellaneous goodies for Psycopg 2
=============================================================

.. sectionauthor:: Daniele Varrazzo <daniele.varrazzo@gmail.com>

.. module:: psycopg2.extras

.. testsetup::

    import psycopg2.extras
    from psycopg2.extras import Inet

    create_test_table()

This module is a generic place used to hold little helper functions and
classes until a better place in the distribution is found.


.. index::
    pair: Cursor; Dictionary

.. _dict-cursor:

Dictionary-like cursor
----------------------

The dict cursors allow to access to the retrieved records using an iterface
similar to the Python dictionaries instead of the tuples. You can use it
either passing `DictConnection` as `connection_factory` argument
to the `~psycopg2.connect()` function or passing `DictCursor` as
the `!cursor_factory` argument to the `~connection.cursor()` method
of a regular `connection`.

    >>> dict_cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
    >>> dict_cur.execute("INSERT INTO test (num, data) VALUES(%s, %s)",
    ...                  (100, "abc'def"))
    >>> dict_cur.execute("SELECT * FROM test")
    >>> rec = dict_cur.fetchone()
    >>> rec['id']
    1
    >>> rec['num']
    100
    >>> rec['data']
    "abc'def"

The records still support indexing as the original tuple:

    >>> rec[2]
    "abc'def"


.. autoclass:: DictCursor

.. autoclass:: DictConnection

.. autoclass:: DictRow


Real dictionary cursor
^^^^^^^^^^^^^^^^^^^^^^

.. autoclass:: RealDictCursor

.. autoclass:: RealDictConnection

.. autoclass:: RealDictRow



.. index::
    pair: Cursor; Logging

Logging cursor
--------------

.. autoclass:: LoggingConnection
    :members: initialize,filter

.. autoclass:: LoggingCursor


.. autoclass:: MinTimeLoggingConnection
    :members: initialize,filter

.. autoclass:: MinTimeLoggingCursor



.. index::
    pair: hstore; Data types
    pair: dict; Adaptation

Hstore data type
----------------

Python `dict` objects can be converted into the PostgreSQL |hstore|_ data
type. Only dictionaries with string/unicode keys and values are supported.
None are also allowed as values.

The |hstore| type has received a lot of improvements in the PostgreSQL 9.0
release and the Psycopg adapter uses a more efficient representation if the
new release is detected.


.. |hstore| replace:: :sql:`hstore`
.. _hstore: http://www.postgresql.org/docs/9.0/static/hstore.html


.. autofunction:: register_hstore



.. index::
    pair: UUID; Data types

UUID data type
--------------

.. versionadded:: 2.0.9
.. versionchanged:: 2.0.13 added UUID array support.

.. doctest::

    >>> psycopg2.extras.register_uuid()
    <psycopg2._psycopg.type object at 0x...>

    >>> # Python UUID can be used in SQL queries
    >>> import uuid
    >>> my_uuid = uuid.UUID('{12345678-1234-5678-1234-567812345678}')
    >>> psycopg2.extensions.adapt(my_uuid).getquoted()
    "'12345678-1234-5678-1234-567812345678'::uuid"

    >>> # PostgreSQL UUID are transformed into Python UUID objects.
    >>> cur.execute("SELECT 'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'::uuid")
    >>> cur.fetchone()[0]
    UUID('a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11')


.. autofunction:: register_uuid

.. autoclass:: UUID_adapter



.. index::
    pair: INET; Data types

:sql:`inet` data type
----------------------

.. versionadded:: 2.0.9

.. doctest::

    >>> psycopg2.extras.register_inet()
    <psycopg2._psycopg.type object at 0x...>

    >>> cur.mogrify("SELECT %s", (Inet('127.0.0.1/32'),))
    "SELECT E'127.0.0.1/32'::inet"

    >>> cur.execute("SELECT '192.168.0.1/24'::inet")
    >>> cur.fetchone()[0].addr
    '192.168.0.1/24'


.. autofunction:: register_inet()

.. autoclass:: Inet



.. index::
    single: Time zones; Fractional

Fractional time zones
---------------------

.. autofunction:: register_tstz_w_secs

    .. versionadded:: 2.0.9

    .. versionchanged:: 2.2.2
        function is no-op: see :ref:`tz-handling`.

.. index::
   pair: Example; Coroutine;

Coroutine support
-----------------

.. autofunction:: wait_select(conn)