Migrating to 1.0
================

The 1.0 release of django-filter introduces several API changes and refinements
that break forwards compatibility. Below is a list of deprecations and
instructions on how to migrate to the 1.0 release. A forwards-compatible 0.15
release has also been created to help with migration. It is compatible with
both the existing and new APIs and will raise warnings for deprecated behavior.


MethodFilter and Filter.action replaced by Filter.method
--------------------------------------------------------
Details: https://github.com/carltongibson/django-filter/pull/382

The functionality of ``MethodFilter`` and ``Filter.action`` has been merged
together and replaced by the ``Filter.method`` parameter. The ``method``
parameter takes either a callable or the name of a ``FilterSet`` method. The
signature now takes an additional ``name`` argument that is the name of the
model field to be filtered on.

Since ``method`` is now a parameter of all filters, inputs are validated and
cleaned by its ``field_class``. The function will receive the cleaned value
instead of the raw value.

.. code-block:: python

    # 0.x
    class UserFilter(FilterSet):
        last_login = filters.MethodFilter()

        def filter_last_login(self, qs, value):
            # try to convert value to datetime, which may fail.
            if value and looks_like_a_date(value):
                value = datetime(value)

            return qs.filter(last_login=value})


    # 1.0
    class UserFilter(FilterSet):
        last_login = filters.CharFilter(method='filter_last_login')

        def filter_last_login(self, qs, name, value):
            return qs.filter(**{name: value})


QuerySet methods are no longer proxied
--------------------------------------
Details: https://github.com/carltongibson/django-filter/pull/440

The ``__iter__()``, ``__len__()``, ``__getitem__()``, ``count()`` methods are
no longer proxied from the queryset. To fix this, call the methods on the
``.qs`` property itself.

.. code-block:: python

    f = UserFilter(request.GET, queryset=User.objects.all())

    # 0.x
    for obj in f:
        ...

    # 1.0
    for obj in f.qs:
        ...


Filters no longer autogenerated when Meta.fields is not specified
-----------------------------------------------------------------
Details: https://github.com/carltongibson/django-filter/pull/450

FilterSets had an undocumented behavior of autogenerating filters for all
model fields when either ``Meta.fields`` was not specified or when set to
``None``. This can lead to potentially unsafe data or schema exposure and
has been deprecated in favor of explicitly setting ``Meta.fields`` to the
``'__all__'`` special value. You may also blacklist fields by setting
the ``Meta.exclude`` attribute.

.. code-block:: python

    class UserFilter(FilterSet):
        class Meta:
            model = User
            fields = '__all__'

    # or
    class UserFilter(FilterSet):
        class Meta:
            model = User
            exclude = ['password']


Move FilterSet options to Meta class
------------------------------------
Details: https://github.com/carltongibson/django-filter/issues/430

Several ``FilterSet`` options have been moved to the ``Meta`` class to prevent
potential conflicts with declared filter names. This includes:

* ``filter_overrides``
* ``strict``
* ``order_by_field``

.. code-block:: python

    # 0.x
    class UserFilter(FilterSet):
        filter_overrides = {}
        strict = STRICTNESS.RAISE_VALIDATION_ERROR
        order_by_field = 'order'
        ...

    # 1.0
    class UserFilter(FilterSet):
        ...

        class Meta:
            filter_overrides = {}
            strict = STRICTNESS.RAISE_VALIDATION_ERROR
            order_by_field = 'order'


FilterSet ordering replaced by OrderingFilter
---------------------------------------------
Details: https://github.com/carltongibson/django-filter/pull/472

The FilterSet ordering options and methods have been deprecated and replaced
by :ref:`OrderingFilter <ordering-filter>`. Deprecated options include:


* ``Meta.order_by``
* ``Meta.order_by_field``

These options retain backwards compatibility with the following caveats:

* ``order_by`` asserts that ``Meta.fields`` is not using the dict syntax. This
  previously was undefined behavior, however the migration code is unable to
  support it.
* Prior, if no ordering was specified in the request, the FilterSet implicitly
  filtered by the first param in the ``order_by`` option. This behavior cannot
  be easily emulated but can be fixed by ensuring that the passed in queryset
  explicitly calls ``.order_by()``.

  .. code-block:: python

      filterset = MyFilterSet(queryset=MyModel.objects.order_by('field'))

The following methods are deprecated and will raise an assertion if present
on the FilterSet:

* ``.get_order_by()``
* ``.get_ordering_field()``

To fix this, simply remove the methods from your class. You can subclass
``OrderingFilter`` to migrate any custom logic.


Deprecated ``FILTERS_HELP_TEXT_FILTER`` and ``FILTERS_HELP_TEXT_EXCLUDE``
-------------------------------------------------------------------------
Details: https://github.com/carltongibson/django-filter/pull/437

Generated filter labels in 1.0 will be more descriptive, including humanized
text about the lookup being performed and if the filter is an exclusion filter.

These settings will no longer have an effect and will be removed in the 1.0 release.