Fixed #29282 -- Prevented some admin checks from crashing with TypeEr…

…ror.

Co-authored-by: David Sanders <[email protected]>

AUTHORS

@@ -748,6 +748,7 @@ answer newbie questions, and generally made Django that much better:
     Sam Newman <http://www.magpiebrain.com/>
     Sander Dijkhuis <[email protected]>
     Sanket Saurav <[email protected]>
+    Sanyam Khurana <[email protected]>
     Sarthak Mehrish <[email protected]>
     [email protected]
     Scot Hacker <[email protected]>

django/contrib/admin/checks.py

@@ -20,6 +20,17 @@
 from django.utils.inspect import get_func_args
 
 
+def _issubclass(cls, classinfo):
+    """
+    issubclass() variant that doesn't raise an exception if cls isn't a
+    class.
+    """
+    try:
+        return issubclass(cls, classinfo)
+    except TypeError:
+        return False
+
+
 def check_admin_app(app_configs, **kwargs):
     from django.contrib.admin.sites import all_sites
     errors = []
@@ -341,7 +352,7 @@ def _check_exclude(self, obj):
 
     def _check_form(self, obj):
         """ Check that form subclasses BaseModelForm. """
-        if not issubclass(obj.form, BaseModelForm):
+        if not _issubclass(obj.form, BaseModelForm):
             return must_inherit_from(parent='BaseModelForm', option='form',
                                      obj=obj, id='admin.E016')
         else:
@@ -640,11 +651,20 @@ def _check_inlines(self, obj):
 
     def _check_inlines_item(self, obj, inline, label):
         """ Check one inline model admin. """
-        inline_label = inline.__module__ + '.' + inline.__name__
+        try:
+            inline_label = inline.__module__ + '.' + inline.__name__
+        except AttributeError:
+            return [
+                checks.Error(
+                    "'%s' must inherit from 'InlineModelAdmin'." % obj,
+                    obj=obj.__class__,
+                    id='admin.E104',
+                )
+            ]
 
         from django.contrib.admin.options import InlineModelAdmin
 
-        if not issubclass(inline, InlineModelAdmin):
+        if not _issubclass(inline, InlineModelAdmin):
             return [
                 checks.Error(
                     "'%s' must inherit from 'InlineModelAdmin'." % inline_label,
@@ -660,7 +680,7 @@ def _check_inlines_item(self, obj, inline, label):
                     id='admin.E105',
                 )
             ]
-        elif not issubclass(inline.model, models.Model):
+        elif not _issubclass(inline.model, models.Model):
             return must_be('a Model', option='%s.model' % inline_label, obj=obj, id='admin.E106')
         else:
             return inline(obj.model, obj.admin_site).check()
@@ -763,7 +783,7 @@ def _check_list_filter_item(self, obj, item, label):
 
         if callable(item) and not isinstance(item, models.Field):
             # If item is option 3, it should be a ListFilter...
-            if not issubclass(item, ListFilter):
+            if not _issubclass(item, ListFilter):
                 return must_inherit_from(parent='ListFilter', option=label,
                                          obj=obj, id='admin.E113')
             # ...  but not a FieldListFilter.
@@ -780,7 +800,7 @@ def _check_list_filter_item(self, obj, item, label):
         elif isinstance(item, (tuple, list)):
             # item is option #2
             field, list_filter_class = item
-            if not issubclass(list_filter_class, FieldListFilter):
+            if not _issubclass(list_filter_class, FieldListFilter):
                 return must_inherit_from(parent='FieldListFilter', option='%s[1]' % label, obj=obj, id='admin.E115')
             else:
                 return []
@@ -1041,7 +1061,7 @@ def _check_min_num(self, obj):
     def _check_formset(self, obj):
         """ Check formset is a subclass of BaseModelFormSet. """
 
-        if not issubclass(obj.formset, BaseModelFormSet):
+        if not _issubclass(obj.formset, BaseModelFormSet):
             return must_inherit_from(parent='BaseModelFormSet', option='formset', obj=obj, id='admin.E206')
         else:
             return []

tests/modeladmin/test_checks.py

@@ -225,11 +225,16 @@ class FakeForm:
         class TestModelAdmin(ModelAdmin):
             form = FakeForm
 
-        self.assertIsInvalid(
-            TestModelAdmin, ValidationTestModel,
-            "The value of 'form' must inherit from 'BaseModelForm'.",
-            'admin.E016'
-        )
+        class TestModelAdminWithNoForm(ModelAdmin):
+            form = 'not a form'
+
+        for model_admin in (TestModelAdmin, TestModelAdminWithNoForm):
+            with self.subTest(model_admin):
+                self.assertIsInvalid(
+                    model_admin, ValidationTestModel,
+                    "The value of 'form' must inherit from 'BaseModelForm'.",
+                    'admin.E016'
+                )
 
     def test_fieldsets_with_custom_form_validation(self):
 
@@ -598,6 +603,40 @@ class TestModelAdmin(ModelAdmin):
             'admin.E112'
         )
 
+    def test_not_list_filter_class(self):
+        class TestModelAdmin(ModelAdmin):
+            list_filter = ['RandomClass']
+
+        self.assertIsInvalid(
+            TestModelAdmin, ValidationTestModel,
+            "The value of 'list_filter[0]' refers to 'RandomClass', which "
+            "does not refer to a Field.",
+            'admin.E116'
+        )
+
+    def test_callable(self):
+        def random_callable():
+            pass
+
+        class TestModelAdmin(ModelAdmin):
+            list_filter = [random_callable]
+
+        self.assertIsInvalid(
+            TestModelAdmin, ValidationTestModel,
+            "The value of 'list_filter[0]' must inherit from 'ListFilter'.",
+            'admin.E113'
+        )
+
+    def test_not_callable(self):
+        class TestModelAdmin(ModelAdmin):
+            list_filter = [[42, 42]]
+
+        self.assertIsInvalid(
+            TestModelAdmin, ValidationTestModel,
+            "The value of 'list_filter[0][1]' must inherit from 'FieldListFilter'.",
+            'admin.E115'
+        )
+
     def test_missing_field(self):
         class TestModelAdmin(ModelAdmin):
             list_filter = ('non_existent_field',)
@@ -655,6 +694,19 @@ class TestModelAdmin(ModelAdmin):
             'admin.E115'
         )
 
+    def test_list_filter_is_func(self):
+        def get_filter():
+            pass
+
+        class TestModelAdmin(ModelAdmin):
+            list_filter = [get_filter]
+
+        self.assertIsInvalid(
+            TestModelAdmin, ValidationTestModel,
+            "The value of 'list_filter[0]' must inherit from 'ListFilter'.",
+            'admin.E113'
+        )
+
     def test_not_associated_with_field_name(self):
         class TestModelAdmin(ModelAdmin):
             list_filter = (BooleanFieldListFilter,)
@@ -918,6 +970,16 @@ class TestModelAdmin(ModelAdmin):
             'admin.E103'
         )
 
+    def test_not_correct_inline_field(self):
+        class TestModelAdmin(ModelAdmin):
+            inlines = [42]
+
+        self.assertIsInvalidRegexp(
+            TestModelAdmin, ValidationTestModel,
+            r"'.*\.TestModelAdmin' must inherit from 'InlineModelAdmin'\.",
+            'admin.E104'
+        )
+
     def test_not_model_admin(self):
         class ValidationTestInline:
             pass
@@ -960,6 +1022,32 @@ class TestModelAdmin(ModelAdmin):
             'admin.E106'
         )
 
+    def test_invalid_model(self):
+        class ValidationTestInline(TabularInline):
+            model = 'Not a class'
+
+        class TestModelAdmin(ModelAdmin):
+            inlines = [ValidationTestInline]
+
+        self.assertIsInvalidRegexp(
+            TestModelAdmin, ValidationTestModel,
+            r"The value of '.*\.ValidationTestInline.model' must be a Model\.",
+            'admin.E106'
+        )
+
+    def test_invalid_callable(self):
+        def random_obj():
+            pass
+
+        class TestModelAdmin(ModelAdmin):
+            inlines = [random_obj]
+
+        self.assertIsInvalidRegexp(
+            TestModelAdmin, ValidationTestModel,
+            r"'.*\.random_obj' must inherit from 'InlineModelAdmin'\.",
+            'admin.E104'
+        )
+
     def test_valid_case(self):
         class ValidationTestInline(TabularInline):
             model = ValidationTestInlineModel
@@ -1102,6 +1190,21 @@ class TestModelAdmin(ModelAdmin):
             invalid_obj=ValidationTestInline
         )
 
+    def test_inline_without_formset_class(self):
+        class ValidationTestInlineWithoutFormsetClass(TabularInline):
+            model = ValidationTestInlineModel
+            formset = 'Not a FormSet Class'
+
+        class TestModelAdminWithoutFormsetClass(ModelAdmin):
+            inlines = [ValidationTestInlineWithoutFormsetClass]
+
+        self.assertIsInvalid(
+            TestModelAdminWithoutFormsetClass, ValidationTestModel,
+            "The value of 'formset' must inherit from 'BaseModelFormSet'.",
+            'admin.E206',
+            invalid_obj=ValidationTestInlineWithoutFormsetClass
+        )
+
     def test_valid_case(self):
         class RealModelFormSet(BaseModelFormSet):
             pass