Add result transforming to bundled transformers

Adds result wrapping capability to the following generic transformers

= TransformCompositeFields
= TransformInterfaceFields
= TransformObjectFields
= TransformRootFields
= ExtendSchema
= MapFields

Adds result wrapping usage to the following transfromers
= WrapFields
= WrapType
= HoistField

packages/utils/src/Interfaces.ts

@@ -153,7 +153,8 @@ export interface Transform {
 
 export type FieldNodeMapper = (
   fieldNode: FieldNode,
-  fragments: Record<string, FragmentDefinitionNode>
+  fragments: Record<string, FragmentDefinitionNode>,
+  context: Record<string, any>
 ) => SelectionNode | Array<SelectionNode>;
 
 export type FieldNodeMappers = Record<string, Record<string, FieldNodeMapper>>;

packages/wrap/src/transforms/ExtendSchema.ts

@@ -1,9 +1,18 @@
 import { GraphQLSchema, extendSchema, parse } from 'graphql';
 
-import { Transform, IFieldResolver, IResolvers, Request, FieldNodeMappers } from '@graphql-tools/utils';
+import {
+  Transform,
+  IFieldResolver,
+  IResolvers,
+  Request,
+  FieldNodeMappers,
+  ExecutionResult,
+} from '@graphql-tools/utils';
 import { addResolversToSchema } from '@graphql-tools/schema';
 import { defaultMergedResolver } from '@graphql-tools/delegate';
 
+import { ObjectValueTransformerMap, ErrorsTransformer } from '../types';
+
 import MapFields from './MapFields';
 
 export default class ExtendSchema implements Transform {
@@ -17,16 +26,24 @@ export default class ExtendSchema implements Transform {
     resolvers = {},
     defaultFieldResolver,
     fieldNodeTransformerMap,
+    objectValueTransformerMap,
+    errorsTransformer,
   }: {
     typeDefs?: string;
     resolvers?: IResolvers;
     defaultFieldResolver?: IFieldResolver<any, any>;
     fieldNodeTransformerMap?: FieldNodeMappers;
+    objectValueTransformerMap?: ObjectValueTransformerMap;
+    errorsTransformer?: ErrorsTransformer;
   }) {
     this.typeDefs = typeDefs;
     this.resolvers = resolvers;
     this.defaultFieldResolver = defaultFieldResolver != null ? defaultFieldResolver : defaultMergedResolver;
-    this.transformer = new MapFields(fieldNodeTransformerMap != null ? fieldNodeTransformerMap : {});
+    this.transformer = new MapFields(
+      fieldNodeTransformerMap != null ? fieldNodeTransformerMap : {},
+      objectValueTransformerMap,
+      errorsTransformer
+    );
   }
 
   public transformSchema(schema: GraphQLSchema): GraphQLSchema {
@@ -41,7 +58,19 @@ export default class ExtendSchema implements Transform {
     });
   }
 
-  public transformRequest(originalRequest: Request): Request {
-    return this.transformer.transformRequest(originalRequest);
+  public transformRequest(
+    originalRequest: Request,
+    delegationContext?: Record<string, any>,
+    transformationContext?: Record<string, any>
+  ): Request {
+    return this.transformer.transformRequest(originalRequest, delegationContext, transformationContext);
+  }
+
+  public transformResult(
+    originalResult: ExecutionResult,
+    delegationContext?: Record<string, any>,
+    transformationContext?: Record<string, any>
+  ): ExecutionResult {
+    return this.transformer.transformResult(originalResult, delegationContext, transformationContext);
   }
 }

packages/wrap/src/transforms/HoistField.ts

@@ -1,37 +1,46 @@
-import { GraphQLSchema, GraphQLObjectType, getNullableType } from 'graphql';
+import { GraphQLSchema, GraphQLObjectType, getNullableType, FieldNode, Kind, GraphQLError } from 'graphql';
 
 import {
-  wrapFieldNode,
   renameFieldNode,
   appendObjectFields,
   removeObjectFields,
   Transform,
   Request,
+  ExecutionResult,
+  relocatedError,
 } from '@graphql-tools/utils';
 
+import { defaultMergedResolver } from '@graphql-tools/delegate';
+
 import MapFields from './MapFields';
-import { createMergedResolver } from '@graphql-tools/delegate';
 
 export default class HoistField implements Transform {
   private readonly typeName: string;
-  private readonly path: Array<string>;
   private readonly newFieldName: string;
   private readonly pathToField: Array<string>;
   private readonly oldFieldName: string;
   private readonly transformer: Transform;
 
-  constructor(typeName: string, path: Array<string>, newFieldName: string) {
+  constructor(typeName: string, path: Array<string>, newFieldName: string, alias = '__gqtlw__') {
     this.typeName = typeName;
-    this.path = path;
     this.newFieldName = newFieldName;
 
-    this.pathToField = this.path.slice();
-    this.oldFieldName = this.pathToField.pop();
-    this.transformer = new MapFields({
-      [typeName]: {
-        [newFieldName]: fieldNode => wrapFieldNode(renameFieldNode(fieldNode, this.oldFieldName), this.pathToField),
+    const pathToField = path.slice();
+    const oldFieldName = pathToField.pop();
+
+    this.oldFieldName = oldFieldName;
+    this.pathToField = pathToField;
+    this.transformer = new MapFields(
+      {
+        [typeName]: {
+          [newFieldName]: fieldNode => wrapFieldNode(renameFieldNode(fieldNode, oldFieldName), pathToField, alias),
+        },
       },
-    });
+      {
+        [typeName]: value => unwrapValue(value, alias),
+      },
+      errors => unwrapErrors(errors, alias)
+    );
   }
 
   public transformSchema(schema: GraphQLSchema): GraphQLSchema {
@@ -53,14 +62,81 @@ export default class HoistField implements Transform {
     newSchema = appendObjectFields(newSchema, this.typeName, {
       [this.newFieldName]: {
         type: targetType,
-        resolve: createMergedResolver({ fromPath: this.pathToField }),
+        resolve: defaultMergedResolver,
       },
     });
 
     return this.transformer.transformSchema(newSchema);
   }
 
-  public transformRequest(originalRequest: Request): Request {
-    return this.transformer.transformRequest(originalRequest);
+  public transformRequest(
+    originalRequest: Request,
+    delegationContext?: Record<string, any>,
+    transformationContext?: Record<string, any>
+  ): Request {
+    return this.transformer.transformRequest(originalRequest, delegationContext, transformationContext);
+  }
+
+  public transformResult(
+    originalResult: ExecutionResult,
+    delegationContext?: Record<string, any>,
+    transformationContext?: Record<string, any>
+  ): ExecutionResult {
+    return this.transformer.transformResult(originalResult, delegationContext, transformationContext);
   }
 }
+
+export function wrapFieldNode(fieldNode: FieldNode, path: Array<string>, alias: string): FieldNode {
+  let newFieldNode = fieldNode;
+  path.forEach(fieldName => {
+    newFieldNode = {
+      kind: Kind.FIELD,
+      alias: {
+        kind: Kind.NAME,
+        value: alias,
+      },
+      name: {
+        kind: Kind.NAME,
+        value: fieldName,
+      },
+      selectionSet: {
+        kind: Kind.SELECTION_SET,
+        selections: [fieldNode],
+      },
+    };
+  });
+
+  return newFieldNode;
+}
+
+export function unwrapValue(originalValue: any, alias: string): any {
+  let newValue = originalValue;
+
+  let object = newValue[alias];
+  while (object != null) {
+    newValue = object;
+    object = newValue[alias];
+  }
+
+  delete originalValue[alias];
+  Object.assign(originalValue, newValue);
+
+  return originalValue;
+}
+
+function unwrapErrors(errors: ReadonlyArray<GraphQLError>, alias: string): Array<GraphQLError> {
+  if (errors === undefined) {
+    return undefined;
+  }
+
+  return errors.map(error => {
+    const originalPath = error.path;
+    if (originalPath == null) {
+      return error;
+    }
+
+    const newPath = originalPath.filter(pathSegment => pathSegment !== alias);
+
+    return relocatedError(error, newPath);
+  });
+}

packages/wrap/src/transforms/MapFields.ts

@@ -4,33 +4,71 @@ import { Transform, Request, FieldNodeMappers, ExecutionResult } from '@graphql-
 
 import TransformCompositeFields from './TransformCompositeFields';
 
+import { ObjectValueTransformerMap, ErrorsTransformer } from '../types';
+
 export default class MapFields implements Transform {
   private readonly transformer: TransformCompositeFields;
 
-  constructor(fieldNodeTransformerMap: FieldNodeMappers) {
+  constructor(
+    fieldNodeTransformerMap: FieldNodeMappers,
+    objectValueTransformerMap?: ObjectValueTransformerMap,
+    errorsTransformer?: ErrorsTransformer
+  ) {
     this.transformer = new TransformCompositeFields(
       (_typeName, _fieldName, fieldConfig) => fieldConfig,
-      (typeName, fieldName, fieldNode, fragments) => {
+      (typeName, fieldName, fieldNode, fragments, context) => {
         const typeTransformers = fieldNodeTransformerMap[typeName];
         if (typeTransformers == null) {
-          return fieldNode;
+          return undefined;
         }
 
         const fieldNodeTransformer = typeTransformers[fieldName];
         if (fieldNodeTransformer == null) {
-          return fieldNode;
+          return undefined;
         }
 
-        return fieldNodeTransformer(fieldNode, fragments);
-      }
+        return fieldNodeTransformer(fieldNode, fragments, context);
+      },
+      objectValueTransformerMap != null
+        ? (data, context) => {
+            if (data == null) {
+              return data;
+            }
+
+            const typeName = data.__typename;
+            if (typeName == null) {
+              return data;
+            }
+
+            const transformer = objectValueTransformerMap[typeName];
+            if (transformer == null) {
+              return data;
+            }
+
+            return transformer(data, context);
+          }
+        : undefined,
+      errorsTransformer != null ? errorsTransformer : undefined
     );
   }
 
   public transformSchema(schema: GraphQLSchema): GraphQLSchema {
     return this.transformer.transformSchema(schema);
   }
 
-  public transformRequest(request: Request): Request {
-    return this.transformer.transformRequest(request);
+  public transformRequest(
+    originalRequest: Request,
+    delegationContext?: Record<string, any>,
+    transformationContext?: Record<string, any>
+  ): Request {
+    return this.transformer.transformRequest(originalRequest, delegationContext, transformationContext);
+  }
+
+  public transformResult(
+    originalResult: ExecutionResult,
+    delegationContext?: Record<string, any>,
+    transformationContext?: Record<string, any>
+  ): ExecutionResult {
+    return this.transformer.transformResult(originalResult, delegationContext, transformationContext);
   }
 }