feat: Add ValidationError code to OperationMessage (#358)

Fix #356

docs/guide/mutations.md

@@ -61,6 +61,9 @@ type OperationMessage {
   The field that caused the error, or `null` if it isn't associated with any particular field.
   """
   field: String
+
+  """The error code, or `null` if no error code was set."""
+  code: String
 }
 
 type Fruit {

strawberry_django/fields/types.py

@@ -178,6 +178,10 @@ class Kind(enum.Enum):
         ),
         default=None,
     )
+    code: Optional[str] = strawberry.field(
+        description="The error code, or `null` if no error code was set.",
+        default=None,
+    )
 
     def __eq__(self, other: Self):
         if not isinstance(other, OperationMessage):
@@ -187,10 +191,11 @@ def __eq__(self, other: Self):
             self.kind == other.kind
             and self.message == other.message
             and self.field == other.field
+            and self.code == other.code
         )
 
     def __hash__(self):
-        return hash((self.__class__, self.kind, self.message, self.field))
+        return hash((self.__class__, self.kind, self.message, self.field, self.code))
 
 
 @strawberry.type

strawberry_django/mutations/fields.py

@@ -52,19 +52,21 @@ def _get_validation_errors(error: Exception):
 
     if isinstance(error, ValidationError) and hasattr(error, "error_dict"):
         # convert field errors
-        for field, field_errors in error.message_dict.items():
+        for field, field_errors in error.error_dict.items():
             for e in field_errors:
                 yield OperationMessage(
                     kind=kind,
                     field=to_camel_case(field) if field != NON_FIELD_ERRORS else None,
-                    message=e,
+                    message=e.message % e.params if e.params else e.message,
+                    code=getattr(e, "code", None),
                 )
     elif isinstance(error, ValidationError) and hasattr(error, "error_list"):
         # convert non-field errors
         for e in error.error_list:
             yield OperationMessage(
                 kind=kind,
                 message=e.message % e.params if e.params else e.message,
+                code=getattr(error, "code", None),
             )
     else:
         msg = getattr(error, "msg", None)
@@ -74,6 +76,7 @@ def _get_validation_errors(error: Exception):
         yield OperationMessage(
             kind=kind,
             message=msg,
+            code=getattr(error, "code", None),
         )
 
 

tests/projects/schema.py

@@ -402,15 +402,29 @@ def create_project(
     ) -> ProjectType:
         """Create project documentation."""
         if cost > 500:
+            # Field error without error code:
             raise ValidationError({"cost": "Cost cannot be higher than 500"})
+        if cost < 0:
+            # Field error with error code:
+            raise ValidationError(
+                {
+                    "cost": ValidationError(
+                        "Cost cannot be lower than zero",
+                        code="min_cost",
+                    ),
+                },
+            )
+        project = Project(
+            name=name,
+            cost=cost,
+            due_date=due_date,
+        )
+        project.full_clean()
+        project.save()
 
         return cast(
             ProjectType,
-            Project.objects.create(
-                name=name,
-                cost=cost,
-                due_date=due_date,
-            ),
+            project,
         )
 
     @mutations.input_mutation(handle_django_errors=True)

tests/projects/snapshots/schema.gql

@@ -380,6 +380,9 @@ type OperationMessage {
   The field that caused the error, or `null` if it isn't associated with any particular field.
   """
   field: String
+
+  """The error code, or `null` if no error code was set."""
+  code: String
 }
 
 enum OperationMessageKind {

tests/test_input_mutations.py

@@ -43,7 +43,88 @@ def test_input_mutation(db, gql_client: GraphQLTestClient):
                 # The cost is properly set, but this user doesn't have
                 # permission to see it
                 "cost": None,
-                "dueDate": "2030-01-01T00:00:00",
+                "dueDate": "2030-01-01",
+            },
+        }
+
+
+@pytest.mark.django_db(transaction=True)
+def test_input_mutation_with_internal_error_code(db, gql_client: GraphQLTestClient):
+    query = """
+    mutation CreateProject ($input: CreateProjectInput!) {
+        createProject (input: $input) {
+          ... on ProjectType {
+            name
+            cost
+          }
+          ... on OperationInfo {
+            messages {
+              field
+              message
+              kind
+              code
+            }
+          }
+        }
+      }
+    """
+    with assert_num_queries(0):
+        res = gql_client.query(
+            query,
+            {"input": {"name": 100 * "way to long", "cost": "10.40"}},
+        )
+        assert res.data == {
+            "createProject": {
+                "messages": [
+                    {
+                        "field": "name",
+                        "kind": "VALIDATION",
+                        "message": (
+                            "Ensure this value has at most 255 characters (it has"
+                            " 1100)."
+                        ),
+                        "code": "max_length",
+                    },
+                ],
+            },
+        }
+
+
+@pytest.mark.django_db(transaction=True)
+def test_input_mutation_with_explicit_error_code(db, gql_client: GraphQLTestClient):
+    query = """
+    mutation CreateProject ($input: CreateProjectInput!) {
+        createProject (input: $input) {
+          ... on ProjectType {
+            name
+            cost
+          }
+          ... on OperationInfo {
+            messages {
+              field
+              message
+              kind
+              code
+            }
+          }
+        }
+      }
+    """
+    with assert_num_queries(0):
+        res = gql_client.query(
+            query,
+            {"input": {"name": "Some Project", "cost": "-1"}},
+        )
+        assert res.data == {
+            "createProject": {
+                "messages": [
+                    {
+                        "field": "cost",
+                        "kind": "VALIDATION",
+                        "message": "Cost cannot be lower than zero",
+                        "code": "min_cost",
+                    },
+                ],
             },
         }
 
@@ -62,6 +143,7 @@ def test_input_mutation_with_errors(db, gql_client: GraphQLTestClient):
               field
               message
               kind
+              code
             }
           }
         }
@@ -79,6 +161,7 @@ def test_input_mutation_with_errors(db, gql_client: GraphQLTestClient):
                         "field": "cost",
                         "kind": "VALIDATION",
                         "message": "Cost cannot be higher than 500",
+                        "code": None,
                     },
                 ],
             },