Database
--------

The ``clld`` database models are declared using SQLAlchemy's
`declarative <http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/index.html>`_
extension. In particular we follow the approach of
`mixins and custom base class <http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html>`_,
to provide building blocks with enough shared commonality for custom data models.

.. _db_objects:

Declarative base and mixins
~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. autoclass:: clld.db.meta.Base
    :members:
    :exclude-members: first, replacement_id


.. autoclass:: clld.db.meta.CustomModelMixin

.. autoclass:: clld.db.models.common.IdNameDescriptionMixin
    :members:


While the above mixin only adds columns to a model, the following mixins do also add
relations between models, thus have to be used in combination, tied together by naming
conventions.

.. autoclass:: clld.db.models.common.DataMixin
    :members:

.. autoclass:: clld.db.models.common.HasDataMixin
    :members:

.. autoclass:: clld.db.models.common.FilesMixin
    :members:

.. autoclass:: clld.db.models.common.HasFilesMixin
    :members:

Typical usage looks like

.. code-block:: python

    class MyModel_data(Base, Versioned, DataMixin):
        pass

    class MyModel_files(Base, Versioned, FilesMixin):
        pass

    class MyModel(Base, HasDataMixin, HasFilesMixin):
        pass




Core models
~~~~~~~~~~~

The CLLD data model includes the following entities commonly found in linguistic databases
and publications:

.. autoclass:: clld.db.models.common.Dataset
    :members:

.. autoclass:: clld.db.models.common.Language
    :members:

.. autoclass:: clld.db.models.common.Parameter
    :members:

.. autoclass:: clld.db.models.common.ValueSet
    :members:

.. autoclass:: clld.db.models.common.Value
    :members:

.. autoclass:: clld.db.models.common.Contribution
    :members:

.. autoclass:: clld.db.models.common.Contributor
    :members:

.. autoclass:: clld.db.models.common.Source
    :members:

.. autoclass:: clld.db.models.common.Unit
    :members:

.. autoclass:: clld.db.models.common.UnitParameter
    :members:

.. autoclass:: clld.db.models.common.UnitValue
    :members: