custom error class

graphql_api/validation.py

@@ -10,6 +10,18 @@
 from graphql.validation import ValidationContext
 
 
+class MissingVariablesError(Exception):
+    """
+    Custom error class to represent errors where required variables defined in the query does
+    not have a matching definition in the variables part of the request. Normally when this
+    scenario occurs it would raise a GraphQLError type but that would cause a uncaught
+    exception for some reason. The aim of this is to surface the error in the response clearly
+    and to prevent internal server errors when it occurs.
+    """
+
+    pass
+
+
 def create_required_variables_rule(variables: Dict) -> Type[ValidationRule]:
     class RequiredVariablesValidationRule(ValidationRule):
         def __init__(self, context: ValidationContext) -> None:
@@ -50,11 +62,8 @@ def enter_operation_definition(
             ]
             print("missing_variables", missing_variables)
             if missing_variables:
-                self.report_error(
-                    GraphQLError(
-                        f"Missing required variables: {', '.join(missing_variables)}",
-                        node,
-                    )
+                raise MissingVariablesError(
+                    f"Missing required variables: {', '.join(missing_variables)}",
                 )
 
     return RequiredVariablesValidationRule

graphql_api/views.py

@@ -29,6 +29,7 @@
 
 from .schema import schema
 from .validation import (
+    MissingVariablesError,
     create_max_aliases_rule,
     create_max_depth_rule,
     create_required_variables_rule,
@@ -264,16 +265,21 @@ async def post(self, request, *args, **kwargs):
             )
 
         with RequestFinalizer(request):
-            print("About to make request")
-            response = await super().post(request, *args, **kwargs)
-            print("Finished request")
+            try:
+                response = await super().post(request, *args, **kwargs)
+            except MissingVariablesError as e:
+                return JsonResponse(
+                    data={
+                        "status": 400,
+                        "detail": str(e),
+                    },
+                    status=400,
+                )
 
             content = response.content.decode("utf-8")
             data = json.loads(content)
 
-            print("Are there errors?", data)
             if "errors" in data:
-                print("Yes there is")
                 inc_counter(
                     GQL_ERROR_TYPE_COUNTER,
                     labels=dict(error_type="all", path=req_path),