fix graphql errors caused by faulty edges.node handling that had been masked when relation fields always returned

Author: swittk

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -670,7 +670,7 @@ export class MongoStorageAdapter implements StorageAdapter {
           // We need to do this because in `mongoObjectToParseObject`, all 'Relation' fields
           // are copied over from schema without any filters. (either keep this filtering here 
           // or pass keys into `mongoObjectToParseObject` via additional optional parameter)
-          if (Array.isArray(keys)) {
+          if (Array.isArray(keys) && keys.length > 0) {
             // set of string keys
             const keysSet = new Set(keys);
             const shouldIncludeField = (fieldName) => {

src/Adapters/Storage/Postgres/PostgresStorageAdapter.js

@@ -1927,7 +1927,7 @@ export class PostgresStorageAdapter implements StorageAdapter {
           // We need to do this because in `postgresObjectToParseObject`, all 'Relation' fields
           // are copied over from schema without any filters. (either keep this filtering here 
           // or pass keys into `postgresObjectToParseObject` via additional optional parameter)
-          if (selectedKeys) {
+          if (selectedKeys.length > 0) {
             // set of string keys
             const keysSet = new Set(selectedKeys);
             const shouldIncludeField = (fieldName) => {

src/GraphQL/loaders/parseClassQueries.js

@@ -108,6 +108,7 @@ const load = function (parseGraphQLSchema, parseClass, parseClassConfig: ?ParseG
             selectedFields
               .filter(field => field.startsWith('edges.node.'))
               .map(field => field.replace('edges.node.', ''))
+              .map(field => field.replace(/\.edges\.node/g, ''))
               .filter(field => field.indexOf('edges.node') < 0)
           );
           const parseOrder = order && order.join(',');

src/GraphQL/loaders/parseClassTypes.js

@@ -387,6 +387,7 @@ const load = (parseGraphQLSchema, parseClass, parseClassConfig: ?ParseGraphQLCla
                   selectedFields
                     .filter(field => field.startsWith('edges.node.'))
                     .map(field => field.replace('edges.node.', ''))
+                    .map(field => field.replace(/\.edges\.node/g, ''))
                     .filter(field => field.indexOf('edges.node') < 0)
                 );
                 const parseOrder = order && order.join(',');

src/GraphQL/parseGraphQLUtils.js

@@ -20,7 +20,15 @@ export function toGraphQLError(error) {
 }
 
 export const extractKeysAndInclude = selectedFields => {
-  selectedFields = selectedFields.filter(field => !field.includes('__typename'));
+  selectedFields = selectedFields
+    .filter(field => !field.includes('__typename'))
+    // GraphQL relation connections expose data under `edges.node.*`. Those
+    // segments do not correspond to actual Parse fields, so strip them to
+    // ensure the root relation key remains in the keys list (e.g. convert
+    // `users.edges.node.username` -> `users.username`). This preserves the
+    // synthetic relation placeholders that Parse injects while still
+    // respecting field projections.
+    .map(field => field.replace(/\.edges\.node/g, ''));
   // Handles "id" field for both current and included objects
   selectedFields = selectedFields.map(field => {
     if (field === 'id') { return 'objectId'; }