Supported Backends
==================

Humphrey supports SQLite, PostgreSQL, and MySQL as data backends, provided that
their adaptors are available (see `SQLAlchemy - Supported Databases`_).

To find out which types of backends are available, a frontend can use::

  from humphrey.core import available_backends

This is a list of dictionaries where each element has the following keys:

``name``
  Name of the database.

``type``
  Type of the database. Possible values are:

  * ``file``: A file-based database.
  * ``tcp``: A TCP socket-based database.

``url``
  Connection string template as required by SQLAlchemy. The template can take
  the following keys for substitution:

  * ``filename``: Name of the database file.
  * ``host``: Address of the host on which the database server runs.
  * ``port``: Port used by the database server.
  * ``dbname``: Name of the database.

``default_host``
  Default value to be used as the database host.

``default_port``
  Default value to be used as the port number to connect to.

.. note:: SQLite is always available.

.. _SQLAlchemy - Supported Databases:
   http://www.sqlalchemy.org/docs/06/dbengine.html#supported-databases