Fixed #36865 -- Removed casting from exact lookups in admin searches.

Instead of casting non-text fields to CharField (which prevents index
usage), skip exact lookups when the search term fails
formfield.to_python().

This preserves index usage for valid searches while gracefully handling
invalid search terms by simply not including them in the query for that
field.

For multi-term searches like 'foo 123' on search_fields=['name', 'age__exact']:
- 'foo': invalid for age, so only name lookup is used
- '123': valid for both, so both lookups are used

This entails a slight increase in permissiveness for search terms that
can be normalized by formfield.to_python().

2 files changed, 79 insertions, 0 deletions

diff --git a/tests/admin_changelist/models.py b/tests/admin_changelist/models.py
index a84c27a066..0b594300d2 100644
--- a/tests/admin_changelist/models.py
+++ b/tests/admin_changelist/models.py
@@ -140,3 +140,10 @@ class CharPK(models.Model):
 class ProxyUser(User):
     class Meta:
         proxy = True
+
+
+class MixedFieldsModel(models.Model):
+    """Model with multiple field types for testing search validation."""
+
+    int_field = models.IntegerField(null=True, blank=True)
+    json_field = models.JSONField(null=True, blank=True)
diff --git a/tests/admin_changelist/tests.py b/tests/admin_changelist/tests.py
index 7a50dbff77..e0772a3e6d 100644
--- a/tests/admin_changelist/tests.py
+++ b/tests/admin_changelist/tests.py
@@ -66,6 +66,7 @@ from .models import (
     Group,
     Invitation,
     Membership,
+    MixedFieldsModel,
     Musician,
     OrderedObject,
     Parent,
@@ -868,6 +869,77 @@ class ChangeListTests(TestCase):
         cl = m.get_changelist_instance(request)
         self.assertCountEqual(cl.queryset, [])
 
+    def test_exact_lookup_mixed_terms(self):
+        """
+        Multi-term search validates each term independently.
+
+        For 'foo 123' with search_fields=['name__icontains', 'age__exact']:
+        - 'foo': age lookup skipped (invalid), name lookup used
+        - '123': both lookups used (valid for age)
+        No Cast should be used; invalid lookups are simply skipped.
+        """
+        child = Child.objects.create(name="foo123", age=123)
+        Child.objects.create(name="other", age=456)
+        m = admin.ModelAdmin(Child, custom_site)
+        m.search_fields = ["name__icontains", "age__exact"]
+
+        request = self.factory.get("/", data={SEARCH_VAR: "foo 123"})
+        request.user = self.superuser
+
+        # One result matching on foo and 123.
+        cl = m.get_changelist_instance(request)
+        self.assertCountEqual(cl.queryset, [child])
+
+        # "xyz" - invalid for age (skipped), no match for name either.
+        request = self.factory.get("/", data={SEARCH_VAR: "xyz"})
+        request.user = self.superuser
+        cl = m.get_changelist_instance(request)
+        self.assertCountEqual(cl.queryset, [])
+
+    def test_exact_lookup_with_more_lenient_formfield(self):
+        """
+        Exact lookups on BooleanField use formfield().to_python() for lenient
+        parsing. Using model field's to_python() would reject 'false' whereas
+        the form field accepts it.
+        """
+        obj = UnorderedObject.objects.create(bool=False)
+        UnorderedObject.objects.create(bool=True)
+        m = admin.ModelAdmin(UnorderedObject, custom_site)
+        m.search_fields = ["bool__exact"]
+
+        # 'false' is accepted by form field but rejected by model field.
+        request = self.factory.get("/", data={SEARCH_VAR: "false"})
+        request.user = self.superuser
+
+        cl = m.get_changelist_instance(request)
+        self.assertCountEqual(cl.queryset, [obj])
+
+    def test_exact_lookup_validates_each_field_independently(self):
+        """
+        Each field validates the search term independently without leaking
+        converted values between fields.
+
+        "3." is valid for IntegerField (converts to 3) but invalid for
+        JSONField. The converted value must not leak to the JSONField check.
+        """
+        # obj_int has int_field=3, should match "3." via IntegerField.
+        obj_int = MixedFieldsModel.objects.create(
+            int_field=3, json_field={"key": "value"}
+        )
+        # obj_json has json_field=3, should NOT match "3." because "3." is
+        # invalid JSON.
+        MixedFieldsModel.objects.create(int_field=99, json_field=3)
+        m = admin.ModelAdmin(MixedFieldsModel, custom_site)
+        m.search_fields = ["int_field__exact", "json_field__exact"]
+
+        # "3." is valid for int (becomes 3) but invalid JSON.
+        # Only obj_int should match via int_field.
+        request = self.factory.get("/", data={SEARCH_VAR: "3."})
+        request.user = self.superuser
+
+        cl = m.get_changelist_instance(request)
+        self.assertCountEqual(cl.queryset, [obj_int])
+
     def test_search_with_exact_lookup_for_non_string_field(self):
         child = Child.objects.create(name="Asher", age=11)
         model_admin = ChildAdmin(Child, custom_site)