refactor(stitching)

- Default delegateToSchema operation to the original operation for root fields and query otherwise.
- Change mergeTypes option to skipTypeMerging to reverse default so that skipTypeMerging should be specified for mergeTypeResolvers but can be omitted for stitching on gateway
- serialize original variable values so that they can be ommited by default

src/Interfaces.ts

@@ -124,7 +124,7 @@ export function isSubschemaConfig(value: SchemaLikeObject): value is SubschemaCo
 
 export interface IDelegateToSchemaOptions<TContext = { [key: string]: any }> {
   schema: GraphQLSchema | SubschemaConfig;
-  operation: Operation;
+  operation?: Operation;
   fieldName: string;
   returnType?: GraphQLOutputType;
   args?: { [key: string]: any };
@@ -133,7 +133,7 @@ export interface IDelegateToSchemaOptions<TContext = { [key: string]: any }> {
   rootValue?: Record<string, any>;
   transforms?: Array<Transform>;
   skipValidation?: boolean;
-  mergeTypes?: boolean;
+  skipTypeMerging?: boolean;
 }
 
 export interface ICreateDelegatingRequestOptions {
@@ -156,7 +156,7 @@ export interface IDelegateRequestOptions<TContext = { [key: string]: any }> {
   returnType?: GraphQLOutputType;
   context?: TContext;
   transforms?: Array<Transform>;
-  mergeTypes?: boolean;
+  skipTypeMerging?: boolean;
 }
 
 export type Delegator = ({ document, context, variables }: {

src/stitching/checkResultAndHandleErrors.ts

@@ -36,7 +36,7 @@ export function checkResultAndHandleErrors(
   responseKey?: string,
   subschema?: GraphQLSchema | SubschemaConfig,
   returnType: GraphQLOutputType = info.returnType,
-  mergeTypes?: boolean,
+  skipTypeMerging?: boolean,
 ): any {
   if (!responseKey) {
     responseKey = getResponseKeyFromInfo(info);
@@ -46,7 +46,7 @@ export function checkResultAndHandleErrors(
   const data = result.data && result.data[responseKey];
   const subschemas = [subschema];
 
-  return handleResult(data, errors, subschemas, context, info, returnType, mergeTypes);
+  return handleResult(data, errors, subschemas, context, info, returnType, skipTypeMerging);
 }
 
 export function handleResult(
@@ -56,7 +56,7 @@ export function handleResult(
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
   returnType = info.returnType,
-  mergeTypes?: boolean,
+  skipTypeMerging?: boolean,
 ): any {
   const type = getNullableType(returnType);
 
@@ -67,9 +67,9 @@ export function handleResult(
   if (isLeafType(type)) {
     return type.parseValue(result);
   } else if (isCompositeType(type)) {
-    return handleObject(type, result, errors, subschemas, context, info, mergeTypes);
+    return handleObject(type, result, errors, subschemas, context, info, skipTypeMerging);
   } else if (isListType(type)) {
-    return handleList(type, result, errors, subschemas, context, info, mergeTypes);
+    return handleList(type, result, errors, subschemas, context, info, skipTypeMerging);
   }
 }
 
@@ -95,20 +95,19 @@ export function handleObject(
   subschemas: Array<GraphQLSchema | SubschemaConfig>,
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
-  mergeTypes?: boolean,
+  skipTypeMerging?: boolean,
 ) {
   makeObjectProxiedResult(object, errors, subschemas);
-
-  if (mergeTypes && info.mergeInfo) {
+  if (skipTypeMerging || !info.mergeInfo) {
+    return object;
+  } else {
     return mergeFields(
       type,
       object,
       subschemas,
       context,
       info,
     );
-  } else {
-    return object;
   }
 }
 
@@ -119,9 +118,8 @@ function handleList(
   subschemas: Array<GraphQLSchema | SubschemaConfig>,
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
-  mergeTypes?: boolean,
+  skipTypeMerging?: boolean,
 ) {
-
   const childErrors = getErrorsByPathSegment(errors);
 
   list = list.map((listMember, index) => handleListMember(
@@ -132,7 +130,7 @@ function handleList(
     subschemas,
     context,
     info,
-    mergeTypes,
+    skipTypeMerging,
   ));
 
   return list;
@@ -146,7 +144,7 @@ function handleListMember(
   subschemas: Array<GraphQLSchema | SubschemaConfig>,
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
-  mergeTypes?: boolean,
+  skipTypeMerging?: boolean,
 ): any {
   if (listMember == null) {
     return handleNull(info.fieldNodes, [...responsePathAsArray(info.path), index], errors);
@@ -155,9 +153,9 @@ function handleListMember(
   if (isLeafType(type)) {
     return type.parseValue(listMember);
   } else if (isCompositeType(type)) {
-    return handleObject(type, listMember, errors, subschemas, context, info, mergeTypes);
+    return handleObject(type, listMember, errors, subschemas, context, info, skipTypeMerging);
   } else if (isListType(type)) {
-    return handleList(type, listMember, errors, subschemas, context, info, mergeTypes);
+    return handleList(type, listMember, errors, subschemas, context, info, skipTypeMerging);
   }
 }
 

src/stitching/defaultMergedResolver.ts

@@ -30,5 +30,5 @@ export default function defaultMergedResolver(
   const result = parent[responseKey];
   const subschemas = getSubschemas(parent);
 
-  return handleResult(result, errors, subschemas, context, info, undefined, true);
+  return handleResult(result, errors, subschemas, context, info);
 }

src/stitching/delegateToSchema.ts

@@ -11,6 +11,11 @@ import {
   validate,
   GraphQLSchema,
   ExecutionResult,
+  GraphQLObjectType,
+  OperationTypeNode,
+  typeFromAST,
+  NamedTypeNode,
+  GraphQLInputType,
 } from 'graphql';
 
 import {
@@ -45,6 +50,20 @@ import { observableToAsyncIterable } from './observableToAsyncIterable';
 import { AddMergedTypeFragments } from '../transforms';
 
 import { isAsyncIterable } from 'iterall';
+import { serializeInputValue } from '../utils';
+
+function getDelegatingOperation(
+  parentType: GraphQLObjectType,
+  schema: GraphQLSchema
+): OperationTypeNode {
+  if (parentType === schema.getMutationType()) {
+    return 'mutation';
+  } else if (parentType === schema.getSubscriptionType()) {
+    return 'subscription';
+  } else {
+    return 'query';
+  }
+}
 
 export default function delegateToSchema(
   options: IDelegateToSchemaOptions | GraphQLSchema,
@@ -60,14 +79,14 @@ export default function delegateToSchema(
     schema: subschema,
     rootValue,
     info,
-    operation = info.operation.operation,
+    operation = getDelegatingOperation(info.parentType, info.schema),
     fieldName,
     returnType = info.returnType,
     args,
     context,
     transforms = [],
     skipValidation,
-    mergeTypes,
+    skipTypeMerging,
   } = options;
 
   const request = createDelegatingRequest({
@@ -90,14 +109,14 @@ export default function delegateToSchema(
     returnType,
     context,
     transforms,
-    mergeTypes,
+    skipTypeMerging,
   });
 }
 
 export function createDelegatingRequest({
   schema: subschema,
   info,
-  operation = info.operation.operation,
+  operation = getDelegatingOperation(info.parentType, info.schema),
   fieldName,
   args,
   transforms = [],
@@ -132,10 +151,6 @@ export function createDelegatingRequest({
     transforms.push(
       new AddArgumentsAsVariables(targetSchema, args, info.schema)
     );
-  } else {
-    console.warn(
-      '"args" undefined. "args" argument may be required in a future version. Custom scalars or enums may not be properly serialized prior to delegation.'
-    );
   }
 
   transforms.push(
@@ -160,12 +175,12 @@ export function delegateRequest({
   schema: subschema,
   rootValue,
   info,
-  operation = info.operation.operation,
+  operation,
   fieldName,
   returnType = info.returnType,
   context,
   transforms = [],
-  mergeTypes,
+  skipTypeMerging,
 }: IDelegateRequestOptions): any {
   let targetSchema: GraphQLSchema;
   let subschemaConfig: SubschemaConfig;
@@ -181,7 +196,7 @@ export function delegateRequest({
   }
 
   transforms = [
-    new CheckResultAndHandleErrors(info, fieldName, subschema, context, returnType, mergeTypes),
+    new CheckResultAndHandleErrors(info, fieldName, subschema, context, returnType, skipTypeMerging),
     ...transforms,
   ];
 
@@ -261,7 +276,7 @@ function createInitialRequest(
     selectionSet,
     name: {
       kind: Kind.NAME,
-      value: targetField,
+      value: targetField || info.fieldNodes[0].name.value,
     },
   };
 
@@ -272,7 +287,7 @@ function createInitialRequest(
 
   const operationDefinition: OperationDefinitionNode = {
     kind: Kind.OPERATION_DEFINITION,
-    operation: targetOperation,
+    operation: targetOperation || getDelegatingOperation(info.parentType, info.schema),
     variableDefinitions: info.operation.variableDefinitions,
     selectionSet: rootSelectionSet,
     name: info.operation.name,
@@ -287,9 +302,17 @@ function createInitialRequest(
     definitions: [operationDefinition, ...fragments],
   };
 
+  const variableValues = info.variableValues;
+  const variables = {};
+  for (const variableDefinition of info.operation.variableDefinitions) {
+    const varName = variableDefinition.variable.name.value;
+    const varType = typeFromAST(info.schema, (variableDefinition.type as NamedTypeNode)) as GraphQLInputType;
+    variables[varName] = serializeInputValue(varType, variableValues[varName]);
+  }
+
   return {
     document,
-    variables: info.variableValues,
+    variables,
   };
 }
 

src/stitching/resolvers.ts

@@ -101,12 +101,9 @@ function defaultCreateProxyingResolver(
 ): GraphQLFieldResolver<any, any> {
   return (parent, args, context, info) => delegateToSchema({
     schema: subschemaConfig,
-    operation,
     fieldName,
-    args,
     context,
     info,
-    mergeTypes: true,
   });
 }
 

src/test/testAlternateMergeSchemas.ts

@@ -1760,6 +1760,7 @@ describe('mergeTypes', () => {
             args: { id: originalResult.id },
             context,
             info,
+            skipTypeMerging: true,
           })
         }
       },
@@ -1777,6 +1778,7 @@ describe('mergeTypes', () => {
             args: { id: originalResult.id },
             context,
             info,
+            skipTypeMerging: true,
           })
         }
       },

src/transforms/CheckResultAndHandleErrors.ts

@@ -9,22 +9,22 @@ export default class CheckResultAndHandleErrors implements Transform {
   private fieldName?: string;
   private subschema?: GraphQLSchema | SubschemaConfig;
   private returnType?: GraphQLOutputType;
-  private mergeTypes?: boolean;
+  private typeMerge?: boolean;
 
   constructor(
     info: IGraphQLToolsResolveInfo,
     fieldName?: string,
     subschema?: GraphQLSchema | SubschemaConfig,
     context?: Record<string, any>,
     returnType: GraphQLOutputType = info.returnType,
-    mergeTypes?: boolean,
+    typeMerge?: boolean,
   ) {
     this.context = context;
     this.info = info;
     this.fieldName = fieldName;
     this.subschema = subschema;
     this.returnType = returnType;
-    this.mergeTypes = mergeTypes;
+    this.typeMerge = typeMerge;
   }
 
   public transformResult(result: any): any {
@@ -35,7 +35,7 @@ export default class CheckResultAndHandleErrors implements Transform {
       this.fieldName,
       this.subschema,
       this.returnType,
-      this.mergeTypes,
+      this.typeMerge,
     );
   }
 }