Fixed #26229 -- Improved check for model admin check admin.E124

Refs #22792

django/contrib/admin/checks.py

@@ -806,10 +806,10 @@ class ModelAdminChecks(BaseModelAdminChecks):
                         id='admin.E123',
                     )
                 ]
-            # Check that list_display_links is set, and that the first values of list_editable and list_display are
-            # not the same. See ticket #22792 for the use case relating to this.
-            elif (obj.list_display[0] in obj.list_editable and obj.list_display[0] != obj.list_editable[0] and
-                  obj.list_display_links is not None):
+            # If list_display[0] is in list_editable, check that
+            # list_display_links is set. See #22792 and #26229 for use cases.
+            elif (obj.list_display[0] == field_name and not obj.list_display_links
+                    and obj.list_display_links is not None):
                 return [
                     checks.Error(
                         "The value of '%s' refers to the first field in 'list_display' ('%s'), "

tests/modeladmin/tests.py

@@ -1553,10 +1553,10 @@ class ListDisplayEditableTests(CheckTestCase):
             list_display_links = None
         self.assertIsValid(ProductAdmin, ValidationTestModel)
 
-    def test_list_display_same_as_list_editable(self):
+    def test_list_display_first_item_same_as_list_editable_first_item(self):
         """
-        The first item in list_display can be the same as the first
-        in list_editable
+        The first item in list_display can be the same as the first in
+        list_editable.
         """
         class ProductAdmin(ModelAdmin):
             list_display = ['name', 'slug', 'pub_date']
@@ -1564,6 +1564,49 @@ class ListDisplayEditableTests(CheckTestCase):
             list_display_links = ['pub_date']
         self.assertIsValid(ProductAdmin, ValidationTestModel)
 
+    def test_list_display_first_item_in_list_editable(self):
+        """
+        The first item in list_display can be in list_editable as long as
+        list_display_links is defined.
+        """
+        class ProductAdmin(ModelAdmin):
+            list_display = ['name', 'slug', 'pub_date']
+            list_editable = ['slug', 'name']
+            list_display_links = ['pub_date']
+        self.assertIsValid(ProductAdmin, ValidationTestModel)
+
+    def test_list_display_first_item_same_as_list_editable_no_list_display_links(self):
+        """
+        The first item in list_display cannot be the same as the first item
+        in list_editable if list_display_links is not defined.
+        """
+        class ProductAdmin(ModelAdmin):
+            list_display = ['name']
+            list_editable = ['name']
+        self.assertIsInvalid(
+            ProductAdmin, ValidationTestModel,
+            "The value of 'list_editable[0]' refers to the first field "
+            "in 'list_display' ('name'), which cannot be used unless "
+            "'list_display_links' is set.",
+            id='admin.E124',
+        )
+
+    def test_list_display_first_item_in_list_editable_no_list_display_links(self):
+        """
+        The first item in list_display cannot be in list_editable if
+        list_display_links isn't defined.
+        """
+        class ProductAdmin(ModelAdmin):
+            list_display = ['name', 'slug', 'pub_date']
+            list_editable = ['slug', 'name']
+        self.assertIsInvalid(
+            ProductAdmin, ValidationTestModel,
+            "The value of 'list_editable[1]' refers to the first field "
+            "in 'list_display' ('name'), which cannot be used unless "
+            "'list_display_links' is set.",
+            id='admin.E124',
+        )
+
 
 class ModelAdminPermissionTests(SimpleTestCase):