Fix server error from PATCH to inventory source (#16274)

Fix server error from PATCH to inventory source, co-authored with Claude opus 4.6

awx/api/fields.py

@@ -89,7 +89,7 @@ class DeprecatedCredentialField(serializers.IntegerField):
     def to_internal_value(self, pk):
         try:
             pk = int(pk)
-        except ValueError:
+        except (ValueError, TypeError):
             self.fail('invalid')
         try:
             Credential.objects.get(pk=pk)

awx/main/tests/functional/api/test_inventory.py

@@ -463,6 +463,26 @@ class TestInventorySourceCredential:
         assert 'Cloud-based inventory sources (such as ec2)' in r.data['credential'][0]
         assert 'require credentials for the matching cloud service' in r.data['credential'][0]
 
+    def test_credential_dict_value_returns_400(self, inventory, admin_user, put):
+        """Passing a dict for the credential field should return 400, not 500.
+
+        Reproduces a bug where int() raises TypeError on non-scalar types
+        (dict, list) which was uncaught, resulting in a 500 Internal Server Error.
+        """
+        inv_src = InventorySource.objects.create(name='test-src', inventory=inventory, source='ec2')
+        r = put(
+            url=reverse('api:inventory_source_detail', kwargs={'pk': inv_src.pk}),
+            data={
+                'name': 'test-src',
+                'inventory': inventory.pk,
+                'source': 'ec2',
+                'credential': {'username': 'admin', 'password': 'secret'},
+            },
+            user=admin_user,
+            expect=400,
+        )
+        assert r.status_code == 400
+
     def test_vault_credential_not_allowed(self, project, inventory, vault_credential, admin_user, post):
         """Vault credentials cannot be associated via the deprecated field"""
         # TODO: when feature is added, add tests to use the related credentials

awx/main/tests/unit/api/test_fields.py

@@ -0,0 +1,49 @@
+import pytest
+from collections import OrderedDict
+from unittest import mock
+
+from rest_framework.exceptions import ValidationError
+
+from awx.api.fields import DeprecatedCredentialField
+
+
+class TestDeprecatedCredentialField:
+    """Test that DeprecatedCredentialField handles unexpected input types gracefully."""
+
+    def test_dict_value_raises_validation_error(self):
+        """Passing a dict instead of an integer should return a 400 validation error, not a 500 TypeError."""
+        field = DeprecatedCredentialField()
+        with pytest.raises(ValidationError):
+            field.to_internal_value({"username": "admin", "password": "secret"})
+
+    def test_ordered_dict_value_raises_validation_error(self):
+        """Passing an OrderedDict should return a 400 validation error, not a 500 TypeError."""
+        field = DeprecatedCredentialField()
+        with pytest.raises(ValidationError):
+            field.to_internal_value(OrderedDict([("username", "admin")]))
+
+    def test_list_value_raises_validation_error(self):
+        """Passing a list should return a 400 validation error, not a 500 TypeError."""
+        field = DeprecatedCredentialField()
+        with pytest.raises(ValidationError):
+            field.to_internal_value([1, 2, 3])
+
+    def test_string_value_raises_validation_error(self):
+        """Passing a non-numeric string should return a 400 validation error."""
+        field = DeprecatedCredentialField()
+        with pytest.raises(ValidationError):
+            field.to_internal_value("not_a_number")
+
+    @mock.patch('awx.api.fields.Credential.objects')
+    def test_valid_integer_value_works(self, mock_cred_objects):
+        """Passing a valid integer PK should work when the credential exists."""
+        mock_cred_objects.get.return_value = mock.MagicMock()
+        field = DeprecatedCredentialField()
+        assert field.to_internal_value(42) == 42
+
+    @mock.patch('awx.api.fields.Credential.objects')
+    def test_valid_string_integer_value_works(self, mock_cred_objects):
+        """Passing a numeric string PK should work when the credential exists."""
+        mock_cred_objects.get.return_value = mock.MagicMock()
+        field = DeprecatedCredentialField()
+        assert field.to_internal_value("42") == 42