GraphQL: Allow true GraphQL Schema Customization (#6360)

* Allow real GraphQL Schema via ParseServer.start

* wip

* working

* tests ok

* add tests about enum/input use case

* Add async function based merge

* Better naming

* remove useless condition

src/GraphQL/loaders/parseClassQueries.js

@@ -14,7 +14,7 @@ const getParseClassQueryConfig = function(
   return (parseClassConfig && parseClassConfig.query) || {};
 };
 
-const getQuery = async (className, _source, args, context, queryInfo) => {
+const getQuery = async (parseClass, _source, args, context, queryInfo) => {
   let { id } = args;
   const { options } = args;
   const { readPreference, includeReadPreference } = options || {};
@@ -23,14 +23,14 @@ const getQuery = async (className, _source, args, context, queryInfo) => {
 
   const globalIdObject = fromGlobalId(id);
 
-  if (globalIdObject.type === className) {
+  if (globalIdObject.type === parseClass.className) {
     id = globalIdObject.id;
   }
 
   const { keys, include } = extractKeysAndInclude(selectedFields);
 
   return await objectsQueries.getObject(
-    className,
+    parseClass.className,
     id,
     keys,
     include,
@@ -38,7 +38,8 @@ const getQuery = async (className, _source, args, context, queryInfo) => {
     includeReadPreference,
     config,
     auth,
-    info
+    info,
+    parseClass
   );
 };
 
@@ -79,7 +80,7 @@ const load = function(
       ),
       async resolve(_source, args, context, queryInfo) {
         try {
-          return await getQuery(className, _source, args, context, queryInfo);
+          return await getQuery(parseClass, _source, args, context, queryInfo);
         } catch (e) {
           parseGraphQLSchema.handleError(e);
         }