Fixes issue ardatan#876, mirror delegateToSchema behavior for standalone

src/Interfaces.ts

@@ -46,13 +46,17 @@ export type Transform = {
   transformResult?: (result: Result) => Result;
 };
 
+export interface IGraphQLToolsResolveInfo extends GraphQLResolveInfo {
+  mergeInfo?: MergeInfo;
+}
+
 export interface IDelegateToSchemaOptions<TContext = { [key: string]: any }> {
   schema: GraphQLSchema;
   operation: Operation;
   fieldName: string;
   args?: { [key: string]: any };
   context: TContext;
-  info: GraphQLResolveInfo;
+  info: IGraphQLToolsResolveInfo;
   transforms?: Array<Transform>;
   skipValidation?: boolean;
 }
@@ -67,6 +71,10 @@ export type MergeInfo = {
     transforms?: Array<Transform>,
   ) => any;
   delegateToSchema<TContext>(options: IDelegateToSchemaOptions<TContext>): any;
+  fragments: Array<{
+    field: string;
+    fragment: string;
+  }>;
 };
 
 export type IFieldResolver<TSource, TContext> = (

src/stitching/delegateToSchema.ts

@@ -30,6 +30,8 @@ import AddArgumentsAsVariables from '../transforms/AddArgumentsAsVariables';
 import FilterToSchema from '../transforms/FilterToSchema';
 import AddTypenameToAbstract from '../transforms/AddTypenameToAbstract';
 import CheckResultAndHandleErrors from '../transforms/CheckResultAndHandleErrors';
+import ExpandAbstractTypes from '../transforms/ExpandAbstractTypes';
+import ReplaceFieldWithFragment from '../transforms/ReplaceFieldWithFragment';
 
 export default function delegateToSchema(
   options: IDelegateToSchemaOptions | GraphQLSchema,
@@ -65,13 +67,23 @@ async function delegateToSchemaImplementation(
     variables: info.variableValues as Record<string, any>,
   };
 
-  const transforms = [
+  let transforms = [
     ...(options.transforms || []),
+    new ExpandAbstractTypes(info.schema, options.schema)
+  ];
+
+  if (info.mergeInfo && info.mergeInfo.fragments) {
+    transforms.push(
+      new ReplaceFieldWithFragment(options.schema, info.mergeInfo.fragments)
+    );
+  }
+
+  transforms = transforms.concat([
     new AddArgumentsAsVariables(options.schema, args),
     new FilterToSchema(options.schema),
     new AddTypenameToAbstract(options.schema),
-    new CheckResultAndHandleErrors(info, options.fieldName),
-  ];
+    new CheckResultAndHandleErrors(info, options.fieldName)
+  ]);
 
   const processedRequest = applyRequestTransforms(rawRequest, transforms);
 

src/stitching/mergeSchemas.ts

@@ -353,13 +353,10 @@ function createMergeInfo(
     delegateToSchema(options: IDelegateToSchemaOptions) {
       return delegateToSchema({
         ...options,
-        transforms: [
-          ...(options.transforms || []),
-          new ExpandAbstractTypes(options.info.schema, options.schema),
-          new ReplaceFieldWithFragment(options.schema, fragments),
-        ],
+        transforms: options.transforms
       });
     },
+    fragments
   };
 }
 

src/test/testDelegateToSchema.ts

@@ -0,0 +1,108 @@
+/* tslint:disable:no-unused-expression */
+
+import { expect } from 'chai';
+import {
+  GraphQLSchema,
+  graphql
+} from 'graphql';
+import { propertySchema, bookingSchema, sampleData, Property } from './testingSchemas';
+import delegateToSchema from '../stitching/delegateToSchema';
+import mergeSchemas from '../stitching/mergeSchemas';
+import { IResolvers } from '../Interfaces';
+
+function findPropertyByLocationName (
+  properties: { [key: string]: Property },
+  name: string
+): Property {
+  for (const key of Object.keys(properties)) {
+    const property = properties[key];
+    if (property.location.name === name) {
+      return property;
+    }
+  }
+}
+
+const COORDINATES_QUERY = `
+  query BookingCoordinates($bookingId: ID!) {
+    bookingById (id: $bookingId) {
+      property {
+        location {
+          coordinates
+        }
+      }
+    }
+  }
+`;
+
+function proxyResolvers (spec: string): IResolvers {
+  return {
+    Booking: {
+      property: {
+        fragment: '... on Booking { propertyId }',
+        resolve (booking, args, context, info) {
+          const delegateFn = spec === 'standalone' ? delegateToSchema :
+            info.mergeInfo.delegateToSchema;
+          return delegateFn({
+            schema: propertySchema,
+            operation: 'query',
+            fieldName: 'propertyById',
+            args: { id: booking.propertyId },
+            context,
+            info
+          });
+        }
+      }
+    },
+    Location: {
+      coordinates: {
+        fragment: '... on Location { name }',
+        resolve (location, args, context, info) {
+          const name = location.name;
+          return findPropertyByLocationName(sampleData.Property, name)
+            .location.coordinates;
+        }
+      }
+    }
+  };
+}
+
+const proxyTypeDefs = `
+  extend type Booking {
+    property: Property!
+  }
+  extend type Location {
+    coordinates: String!
+  }
+`;
+
+describe('stitching', () => {
+  describe('delegateToSchema', () => {
+    ['standalone', 'info.mergeInfo'].forEach(spec => {
+      context(spec, () => {
+        let schema: GraphQLSchema;
+        before(() => {
+          schema = mergeSchemas({
+            schemas: [bookingSchema, propertySchema, proxyTypeDefs],
+            resolvers: proxyResolvers(spec)
+          });
+        });
+        it('should add fragments for deep types', async () => {
+          const result = await graphql(schema, COORDINATES_QUERY,
+            {}, {}, { bookingId: 'b1' });
+
+          expect(result).to.deep.equal({
+            data: {
+              bookingById: {
+                property: {
+                  location: {
+                    coordinates: sampleData.Property.p1.location.coordinates
+                  }
+                }
+              }
+            }
+          });
+        });
+      });
+    });
+  });
+});

src/test/testingSchemas.ts

@@ -22,12 +22,15 @@ import makeRemoteExecutableSchema, {
 import introspectSchema from '../stitching/introspectSchema';
 import { PubSub } from 'graphql-subscriptions';
 
+export type Location = {
+  name: string;
+  coordinates: string;
+};
+
 export type Property = {
   id: string;
   name: string;
-  location: {
-    name: string;
-  };
+  location: Location;
 };
 
 export type Product = {
@@ -84,20 +87,23 @@ export const sampleData: {
       name: 'Super great hotel',
       location: {
         name: 'Helsinki',
+        coordinates: '60.1698° N, 24.9383° E'
       },
     },
     p2: {
       id: 'p2',
       name: 'Another great hotel',
       location: {
         name: 'San Francisco',
+        coordinates: '37.7749° N, 122.4194° W'
       },
     },
     p3: {
       id: 'p3',
       name: 'BedBugs - The Affordable Hostel',
       location: {
         name: 'Helsinki',
+        coordinates: '60.1699° N, 24.9384° E'
       },
     },
   },

src/test/tests.ts

@@ -10,3 +10,4 @@ import './testTransforms';
 import './testAlternateMergeSchemas';
 import './testErrors';
 import './testDirectives';
+import './testDelegateToSchema';