debian-django-filter/docs/ref/filterset.txt

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FilterSet Guide
===============
This document provides a guide on using additional FilterSet features.
Meta options
------------
- :ref:`model <model>`
- :ref:`fields <fields>`
- :ref:`exclude <exclude>`
- :ref:`order_by <order-by>`
- :ref:`form <form>`
- :ref:`together <together>`
.. _model:
Automatic filter generation with ``model``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``FilterSet`` is capable of automatically generating filters for a given
``model``'s fields. Similar to Django's ``ModelForm``, filters are created
based on the underlying model field's type. This option must be combined with
either the ``fields`` or ``exclude`` option, which is the same requirement for
Django's ``ModelForm`` class, detailed `here`__.
__ https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#selecting-the-fields-to-use
.. code-block:: python
class UserFilter(django_filters.FilterSet):
class Meta:
model = User
fields = ['username', 'last_login']
.. _fields:
Declaring filterable ``fields``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``fields`` option is combined with ``model`` to automatically generate
filters. Note that generated filters will not overwrite filters declared on
the ``FilterSet``. The ``fields`` option accepts two syntaxes:
* a list of field names
* a dictionary of field names mapped to a list of lookups
.. code-block:: python
class UserFilter(django_filters.FilterSet):
class Meta:
model = User
fields = ['username', 'last_login']
# or
class UserFilter(django_filters.FilterSet):
class Meta:
model = User
fields = {
'username': ['exact', 'contains'],
'last_login': ['exact', 'year__gt'],
}
The list syntax will create an ``exact`` lookup filter for each field included
in ``fields``. The dictionary syntax will create a filter for each lookup
expression declared for its corresponding model field. These expressions may
include both transforms and lookups, as detailed in the `lookup reference`__.
__ https://docs.djangoproject.com/en/dev/ref/models/lookups/#module-django.db.models.lookups
.. _exclude:
Disable filter fields with ``exclude``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The ``exclude`` option accepts a blacklist of field names to exclude from
automatic filter generation. Note that this option will not disable filters
declared directly on the ``FilterSet``.
.. code-block:: python
class UserFilter(django_filters.FilterSet):
class Meta:
model = User
exclude = ['password']
.. _order-by:
Ordering using ``order_by``
~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can allow the user to control ordering by providing the
``order_by`` argument in the Filter's Meta class. ``order_by`` can be either a
``list`` or ``tuple`` of field names, in which case those are the options, or
it can be a ``bool`` which, if True, indicates that all fields that
the user can filter on can also be sorted on. An example of ordering using a list::
import django_filters
class ProductFilter(django_filters.FilterSet):
price = django_filters.NumberFilter(lookup_expr='lt')
class Meta:
model = Product
fields = ['price', 'release_date']
order_by = ['price']
If you want to control the display of items in ``order_by``, you can set it to
a list or tuple of 2-tuples in the format ``(field_name, display_name)``.
This lets you override the displayed names for your ordering fields::
order_by = (
('name', 'Company Name'),
('average_rating', 'Stars'),
)
Note that the default query parameter name used for ordering is ``o``. You
can override this by setting an ``order_by_field`` attribute on the
``FilterSet`` class to the string value you would like to use.
.. _form:
Custom Forms using ``form``
~~~~~~~~~~~~~~~~~~~~~~~~~~~
The inner ``Meta`` class also takes an optional ``form`` argument. This is a
form class from which ``FilterSet.form`` will subclass. This works similar to
the ``form`` option on a ``ModelAdmin.``
.. _together:
Group fields with ``together``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The inner ``Meta`` class also takes an optional ``together`` argument. This
is a list of lists, each containing field names. For convenience can be a
single list/tuple when dealing with a single set of fields. Fields within a
field set must either be all or none present in the request for
``FilterSet.form`` to be valid::
import django_filters
class ProductFilter(django_filters.FilterSet):
class Meta:
model = Product
fields = ['price', 'release_date', 'rating']
together = ['rating', 'price']
Non-Meta options
----------------
Note that these options do not go in the Meta class, they are specified directly
in your FilterSet class.
- filter_overrides
- order_by_field
- :ref:`strict <strict>`
.. _strict:
``strict``
~~~~~~~~~~
The ``strict`` option controls whether results are returned when an invalid
value is specified by the user for any filter field. By default, ``strict`` is
set to ``STRICTNESS.RETURN_NO_RESULTS`` meaning that an empty queryset is
returned if any field contains an invalid value. You can loosen this behavior
by setting ``strict`` to ``STRICTNESS.IGNORE`` which will effectively ignore a
filter field if its value is invalid. A third option of
``STRICTNESS.RAISE_VALIDATION_ERROR`` will cause a ``ValidationError`` to be
raised if any field contains an invalid value.
Overriding ``FilterSet`` methods
--------------------------------
``filter_for_lookup()``
~~~~~~~~~~~~~~~~~~~~~~~
Prior to version 0.13.0, filter generation did not take into account the
``lookup_expr`` used. This commonly caused malformed filters to be generated
for 'isnull', 'in', and 'range' lookups (as well as transformed lookups). The
current implementation provides the following behavior:
- 'isnull' lookups return a ``BooleanFilter``
- 'in' lookups return a filter derived from the CSV-based ``BaseInFilter``.
- 'range' lookups return a filter derived from the CSV-based ``BaseRangeFilter``.
If you want to override the ``filter_class`` and ``params`` used to instantiate
filters for a model field, you can override ``filter_for_lookup()``. Ex::
class ProductFilter(django_filters.FilterSet):
class Meta:
model = Product
fields = {
'release_date': ['exact', 'range'],
}
@classmethod
def filter_for_lookup(cls, f, lookup_type):
# override date range lookups
if isinstance(f, models.DateField) and lookup_type == 'range':
return django_filters.DateRangeFiler, {}
# use default behavior otherwise
return super(ProductFilter, cls).filter_for_lookup(f, lookup_type)
``get_ordering_field()``
~~~~~~~~~~~~~~~~~~~~~~~~
If you want to use a custom widget, or in any other way override the ordering
field you can override the ``get_ordering_field()`` method on a ``FilterSet``.
This method just needs to return a Form Field.
Ordering on multiple fields, or other complex orderings can be achieved by
overriding the ``FilterSet.get_order_by()`` method. This is passed the selected
``order_by`` value, and is expected to return an iterable of values to pass to
``QuerySet.order_by``. For example, to sort a ``User`` table by last name, then
first name::
class UserFilter(django_filters.FilterSet):
class Meta:
order_by = (
('username', 'Username'),
('last_name', 'Last Name')
)
def get_order_by(self, order_value):
if order_value == 'last_name':
return ['last_name', 'first_name']
return super(UserFilter, self).get_order_by(order_value)