Add unknown_field_behavior feature

django_filters/__init__.py

@@ -2,7 +2,7 @@
 from importlib import util as importlib_util
 
 from .filters import *
-from .filterset import FilterSet
+from .filterset import FilterSet, UnknownFieldBehavior
 
 # We make the `rest_framework` module available without an additional import.
 #   If DRF is not installed, no-op.

django_filters/filterset.py

@@ -1,5 +1,7 @@
 import copy
+import warnings
 from collections import OrderedDict
+from enum import Enum
 
 from django import forms
 from django.db import models
@@ -43,6 +45,12 @@ def remote_queryset(field):
     return model._default_manager.complex_filter(limit_choices_to)
 
 
+class UnknownFieldBehavior(Enum):
+    RAISE = "raise"
+    WARN = "warn"
+    IGNORE = "ignore"
+
+
 class FilterSetOptions:
     def __init__(self, options=None):
         self.model = getattr(options, "model", None)
@@ -53,6 +61,13 @@ def __init__(self, options=None):
 
         self.form = getattr(options, "form", forms.Form)
 
+        behavior = getattr(options, "unknown_field_behavior", UnknownFieldBehavior.RAISE)
+
+        if not isinstance(behavior, UnknownFieldBehavior):
+            raise ValueError(f"Invalid unknown_field_behavior: {behavior}")
+
+        self.unknown_field_behavior = behavior
+
 
 class FilterSetMetaclass(type):
     def __new__(cls, name, bases, attrs):
@@ -338,9 +353,11 @@ def get_filters(cls):
                     continue
 
                 if field is not None:
-                    filters[filter_name] = cls.filter_for_field(
+                    filter_instance = cls.filter_for_field(
                         field, field_name, lookup_expr
                     )
+                    if filter_instance is not None:
+                        filters[filter_name] = filter_instance
 
         # Allow Meta.fields to contain declared filters *only* when a list/tuple
         if isinstance(cls._meta.fields, (list, tuple)):
@@ -357,6 +374,18 @@ def get_filters(cls):
         filters.update(cls.declared_filters)
         return filters
 
+    @classmethod
+    def handle_unrecognized_field(cls, field_name, message):
+        behavior = cls._meta.unknown_field_behavior
+        if behavior == UnknownFieldBehavior.RAISE:
+            raise AssertionError(message)
+        elif behavior == UnknownFieldBehavior.WARN:
+            warnings.warn(f"Unrecognized field type for '{field_name}'. Field will be ignored.")
+        elif behavior == UnknownFieldBehavior.IGNORE:
+            pass
+        else:
+            raise ValueError(f"Invalid unknown_field_behavior: {behavior}")
+
     @classmethod
     def filter_for_field(cls, field, field_name, lookup_expr=None):
         if lookup_expr is None:
@@ -371,12 +400,14 @@ def filter_for_field(cls, field, field_name, lookup_expr=None):
         filter_class, params = cls.filter_for_lookup(field, lookup_type)
         default.update(params)
 
-        assert filter_class is not None, (
-            "%s resolved field '%s' with '%s' lookup to an unrecognized field "
-            "type %s. Try adding an override to 'Meta.filter_overrides'. See: "
-            "https://django-filter.readthedocs.io/en/main/ref/filterset.html"
-            "#customise-filter-generation-with-filter-overrides"
-        ) % (cls.__name__, field_name, lookup_expr, field.__class__.__name__)
+        if filter_class is None:
+            cls.handle_unrecognized_field(field_name, (
+                "%s resolved field '%s' with '%s' lookup to an unrecognized field "
+                "type %s. Try adding an override to 'Meta.filter_overrides'. See: "
+                "https://django-filter.readthedocs.io/en/main/ref/filterset.html"
+                "#customise-filter-generation-with-filter-overrides"
+            ) % (cls.__name__, field_name, lookup_expr, field.__class__.__name__))
+            return None
 
         return filter_class(**default)
 

docs/ref/filterset.txt

@@ -12,6 +12,7 @@ Meta options
 - :ref:`exclude <exclude>`
 - :ref:`form <form>`
 - :ref:`filter_overrides <filter_overrides>`
+- :ref:`unknown_field_behavior <unknown_field_behavior>`
 
 
 .. _model:
@@ -146,6 +147,34 @@ This is a map of model fields to filter classes with options::
                 },
             }
 
+
+.. _unknown_field_behavior:
+
+Handling unknown fields with ``unknown_field_behavior``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``unknown_field_behavior`` option specifies how unknown fields are handled 
+in a ``FilterSet``. You can set this option using the values of the 
+``UnknownFieldBehavior`` enum:
+
+- ``UnknownFieldBehavior.RAISE``: Raise an assertion error (default)
+- ``UnknownFieldBehavior.WARN``: Issue a warning and ignore the field
+- ``UnknownFieldBehavior.IGNORE``: Silently ignore the field
+
+Note that both the ``WARN`` and ``IGNORE`` options do not include the unknown 
+field(s) in the list of filters.
+
+.. code-block:: python
+
+    from django_filters import UnknownFieldBehavior
+
+    class UserFilter(django_filters.FilterSet):
+        class Meta:
+            model = User
+            fields = ['username', 'last_login']
+            unknown_field_behavior = UnknownFieldBehavior.WARN
+
+
 Overriding ``FilterSet`` methods
 --------------------------------
 

tests/test_filterset.py

@@ -1,4 +1,5 @@
 import unittest
+import warnings
 from unittest import mock
 
 from django.db import models
@@ -23,6 +24,7 @@
 from django_filters.filterset import (
     FILTER_FOR_DBFIELD_DEFAULTS,
     FilterSet,
+    UnknownFieldBehavior,
     filterset_factory,
 )
 from django_filters.widgets import BooleanWidget
@@ -147,6 +149,7 @@ def test_field_that_is_subclassed(self):
 
     def test_unknown_field_type_error(self):
         f = NetworkSetting._meta.get_field("mask")
+        FilterSet._meta.unknown_field_behavior = UnknownFieldBehavior.RAISE
 
         with self.assertRaises(AssertionError) as excinfo:
             FilterSet.filter_for_field(f, "mask")
@@ -157,6 +160,14 @@ def test_unknown_field_type_error(self):
             excinfo.exception.args[0],
         )
 
+    def test_return_none(self):
+        f = NetworkSetting._meta.get_field("mask")
+        # Set unknown_field_behavior to 'ignore' to avoid raising exceptions
+        FilterSet._meta.unknown_field_behavior = UnknownFieldBehavior.IGNORE
+        result = FilterSet.filter_for_field(f, "mask")
+
+        self.assertIsNone(result)
+
     def test_symmetrical_selfref_m2m_field(self):
         f = Node._meta.get_field("adjacents")
         result = FilterSet.filter_for_field(f, "adjacents")
@@ -202,6 +213,73 @@ def test_filter_overrides(self):
         pass
 
 
+class HandleUnknownFieldTests(TestCase):
+    def setUp(self):
+        class NetworkSettingFilterSet(FilterSet):
+            class Meta:
+                model = NetworkSetting
+                fields = ["ip", "mask"]
+                # Initial field behavior set to 'ignore' to avoid crashing in setUp
+                unknown_field_behavior = UnknownFieldBehavior.IGNORE
+
+        self.FilterSet = NetworkSettingFilterSet
+
+    def test_raise_unknown_field_behavior(self):
+        self.FilterSet._meta.unknown_field_behavior = UnknownFieldBehavior.RAISE
+
+        with self.assertRaises(AssertionError) as excinfo:
+            self.FilterSet.handle_unrecognized_field("mask", "test_message")
+
+        self.assertIn(
+            "test_message",
+            excinfo.exception.args[0],
+        )
+
+    def test_unknown_field_warn_behavior(self):
+        self.FilterSet._meta.unknown_field_behavior = UnknownFieldBehavior.WARN
+
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter("always")
+            self.FilterSet.handle_unrecognized_field("mask", "test_message")
+
+        self.assertIn(
+            "Unrecognized field type for 'mask'. "
+            "Field will be ignored.",
+            str(w[-1].message),
+        )
+
+    def test_unknown_field_ignore_behavior(self):
+        # No exception or warning should be raised
+        self.FilterSet._meta.unknown_field_behavior = UnknownFieldBehavior.IGNORE
+        self.FilterSet.handle_unrecognized_field("mask", "test_message")
+
+    def test_unknown_field_invalid_initial_behavior(self):
+        # Creation of new custom FilterSet to set initial field behavior
+        with self.assertRaises(ValueError) as excinfo:
+
+            class InvalidBehaviorFilterSet(FilterSet):
+                class Meta:
+                    model = NetworkSetting
+                    fields = ["ip", "mask"]
+                    unknown_field_behavior = "invalid"
+
+        self.assertIn(
+            "Invalid unknown_field_behavior: invalid",
+            str(excinfo.exception),
+        )
+
+    def test_unknown_field_invalid_changed_option_behavior(self):
+        self.FilterSet._meta.unknown_field_behavior = "invalid"
+
+        with self.assertRaises(ValueError) as excinfo:
+            self.FilterSet.handle_unrecognized_field("mask", "test_message")
+
+        self.assertIn(
+            "Invalid unknown_field_behavior: invalid",
+            str(excinfo.exception),
+        )
+
+
 class FilterSetFilterForLookupTests(TestCase):
     def test_filter_for_ISNULL_lookup(self):
         f = Article._meta.get_field("author")