Refs #26001 -- Handled relationship exact lookups in ModelAdmin.search_fields.

django/contrib/admin/options.py

@@ -1178,17 +1178,17 @@ class ModelAdmin(BaseModelAdmin):
         # Apply keyword searches.
         def construct_search(field_name):
             if field_name.startswith("^"):
-                return "%s__istartswith" % field_name.removeprefix("^")
+                return "%s__istartswith" % field_name.removeprefix("^"), None
             elif field_name.startswith("="):
-                return "%s__iexact" % field_name.removeprefix("=")
+                return "%s__iexact" % field_name.removeprefix("="), None
             elif field_name.startswith("@"):
-                return "%s__search" % field_name.removeprefix("@")
+                return "%s__search" % field_name.removeprefix("@"), None
             # Use field_name if it includes a lookup.
             opts = queryset.model._meta
             lookup_fields = field_name.split(LOOKUP_SEP)
             # Go through the fields, following all relations.
             prev_field = None
-            for path_part in lookup_fields:
+            for i, path_part in enumerate(lookup_fields):
                 if path_part == "pk":
                     path_part = opts.pk.name
                 try:
@@ -1196,44 +1196,39 @@ class ModelAdmin(BaseModelAdmin):
                 except FieldDoesNotExist:
                     # Use valid query lookups.
                     if prev_field and prev_field.get_lookup(path_part):
-                        return field_name
+                        if path_part == "exact" and not isinstance(
+                            prev_field, (models.CharField, models.TextField)
+                        ):
+                            field_name_without_exact = "__".join(lookup_fields[:i])
+                            alias = Cast(
+                                field_name_without_exact,
+                                output_field=models.CharField(),
+                            )
+                            alias_name = "_".join(lookup_fields[:i])
+                            return f"{alias_name}_str", alias
+                        else:
+                            return field_name, None
                 else:
                     prev_field = field
                     if hasattr(field, "path_infos"):
                         # Update opts to follow the relation.
                         opts = field.path_infos[-1].to_opts
             # Otherwise, use the field with icontains.
-            return "%s__icontains" % field_name
+            return "%s__icontains" % field_name, None
 
         may_have_duplicates = False
         search_fields = self.get_search_fields(request)
         if search_fields and search_term:
-            str_annotations = {}
+            str_aliases = {}
             orm_lookups = []
             for field in search_fields:
-                if field.endswith("__exact"):
-                    field_name = field.rsplit("__exact", 1)[0]
-                    try:
-                        field_obj = queryset.model._meta.get_field(field_name)
-                    except FieldDoesNotExist:
-                        lookup = construct_search(field)
-                        orm_lookups.append(lookup)
-                        continue
-                    # Add string cast annotations for non-string exact lookups.
-                    if not isinstance(field_obj, (models.CharField, models.TextField)):
-                        str_annotations[f"{field_name}_str"] = Cast(
-                            field_name, output_field=models.CharField()
-                        )
-                        orm_lookups.append(f"{field_name}_str__exact")
-                    else:
-                        lookup = construct_search(field)
-                        orm_lookups.append(lookup)
-                else:
-                    lookup = construct_search(str(field))
-                    orm_lookups.append(lookup)
+                lookup, str_alias = construct_search(str(field))
+                orm_lookups.append(lookup)
+                if str_alias:
+                    str_aliases[lookup] = str_alias
 
-            if str_annotations:
-                queryset = queryset.annotate(**str_annotations)
+            if str_aliases:
+                queryset = queryset.alias(**str_aliases)
 
             term_queries = []
             for bit in smart_split(search_term):

tests/admin_changelist/admin.py

@@ -56,6 +56,7 @@ class ChildAdmin(admin.ModelAdmin):
 
 class GrandChildAdmin(admin.ModelAdmin):
     list_display = ["name", "parent__name", "parent__parent__name"]
+    search_fields = ["parent__name__exact", "parent__age__exact"]
 
 
 site.register(GrandChild, GrandChildAdmin)

tests/admin_changelist/tests.py

@@ -879,6 +879,28 @@ class ChangeListTests(TestCase):
                     cl = model_admin.get_changelist_instance(request)
                 self.assertCountEqual(cl.queryset, expected_result)
 
+    def test_search_with_exact_lookup_relationship_field(self):
+        child = Child.objects.create(name="I am a child", age=11)
+        grandchild = GrandChild.objects.create(name="I am a grandchild", parent=child)
+        model_admin = GrandChildAdmin(GrandChild, custom_site)
+
+        request = self.factory.get("/", data={SEARCH_VAR: "'I am a child'"})
+        request.user = self.superuser
+        cl = model_admin.get_changelist_instance(request)
+        self.assertCountEqual(cl.queryset, [grandchild])
+        for search_term, expected_result in [
+            ("11", [grandchild]),
+            ("'I am a child'", [grandchild]),
+            ("1", []),
+            ("A", []),
+            ("random", []),
+        ]:
+            request = self.factory.get("/", data={SEARCH_VAR: search_term})
+            request.user = self.superuser
+            with self.subTest(search_term=search_term):
+                cl = model_admin.get_changelist_instance(request)
+                self.assertCountEqual(cl.queryset, expected_result)
+
     def test_no_distinct_for_m2m_in_list_filter_without_params(self):
         """
         If a ManyToManyField is in list_filter but isn't in any lookup params,