feat(stitching): support advanced type merging

Also fixes algorithmic error in type merging in which previously not recorded the correct originating subschema for fields. Nested type merging is now enabled, with tests (hopefully!) to follow.
yaacovCR · Jan 23, 2020 · 3bdc30e · 3bdc30e
1 parent f547f61
commit 3bdc30e
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Showing 11 changed files with 367 additions and 137 deletions.
diff --git a/src/Interfaces.ts b/src/Interfaces.ts
@@ -24,6 +24,8 @@ import {
   GraphQLOutputType,
 } from 'graphql';
 
+import { TypeMap } from 'graphql/type/schema';
+
 import { SchemaDirectiveVisitor } from './utils/SchemaDirectiveVisitor';
 import { SchemaVisitor } from './utils/SchemaVisitor';
 
@@ -100,14 +102,16 @@ export type SubschemaConfig = {
 
 export type MergedTypeConfig = {
   fragment?: string;
-  mergedTypeResolver: MergedTypeResolver;
+  parsedFragment?: InlineFragmentNode,
+  merge: MergedTypeResolver;
 };
 
 export type MergedTypeResolver = (
-  subschema: GraphQLSchema | SubschemaConfig,
   originalResult: any,
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
+  subschema: GraphQLSchema | SubschemaConfig,
+  fieldNodes: Array<FieldNode>,
 ) => any;
 
 export type GraphQLSchemaWithTransforms = GraphQLSchema & { transforms?: Array<Transform> };
@@ -171,18 +175,21 @@ export type MergeInfo = {
     fragment: string;
   }>;
   replacementFragments: ReplacementFragmentMapping,
-  mergedTypes: MergedTypeMapping,
+  mergedTypes: Record<string, MergedTypeInfo>,
   delegateToSchema<TContext>(options: IDelegateToSchemaOptions<TContext>): any;
 };
 
 export type ReplacementFragmentMapping = {
   [typeName: string]: { [fieldName: string]: InlineFragmentNode };
 };
 
-export type MergedTypeMapping = Record<string, {
-  fragment: InlineFragmentNode,
+export type MergedTypeInfo = {
   subschemas: Array<SubschemaConfig>,
-}>;
+  fragment?: InlineFragmentNode,
+  uniqueFields: Record<string, SubschemaConfig>,
+  nonUniqueFields: Record<string, Array<SubschemaConfig>>,
+  typeMaps: Map<SubschemaConfig, TypeMap>,
+};
 
 export type IFieldResolver<TSource, TContext, TArgs = Record<string, any>> = (
   source: TSource,

diff --git a/src/stitching/checkResultAndHandleErrors.ts b/src/stitching/checkResultAndHandleErrors.ts
@@ -14,6 +14,7 @@ import {
   GraphQLSchema,
   FieldNode,
   isAbstractType,
+  GraphQLObjectType,
 } from 'graphql';
 import { getResponseKeyFromInfo } from './getResponseKeyFromInfo';
 import {
@@ -24,10 +25,12 @@ import {
 import {
   SubschemaConfig,
   IGraphQLToolsResolveInfo,
+  isSubschemaConfig,
 } from '../Interfaces';
 import resolveFromParentTypename from './resolveFromParentTypename';
-import { setErrors, setSubschemas } from './proxiedResult';
-import { mergeDeep } from '../utils';
+import { setErrors, setObjectSubschema } from './proxiedResult';
+import { collectFields } from '../utils';
+import { mergeFields } from './mergeFields';
 
 export function checkResultAndHandleErrors(
   result: ExecutionResult,
@@ -44,15 +47,14 @@ export function checkResultAndHandleErrors(
 
   const errors = result.errors || [];
   const data = result.data && result.data[responseKey];
-  const subschemas = [subschema];
 
-  return handleResult(data, errors, subschemas, context, info, returnType, skipTypeMerging);
+  return handleResult(data, errors, subschema, context, info, returnType, skipTypeMerging);
 }
 
 export function handleResult(
   result: any,
   errors: ReadonlyArray<GraphQLError>,
-  subschemas: Array<GraphQLSchema | SubschemaConfig>,
+  subschema: GraphQLSchema | SubschemaConfig,
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
   returnType = info.returnType,
@@ -67,55 +69,17 @@ export function handleResult(
   if (isLeafType(type)) {
     return type.parseValue(result);
   } else if (isCompositeType(type)) {
-    return handleObject(type, result, errors, subschemas, context, info, skipTypeMerging);
+    return handleObject(type, result, errors, subschema, context, info, skipTypeMerging);
   } else if (isListType(type)) {
-    return handleList(type, result, errors, subschemas, context, info, skipTypeMerging);
-  }
-}
-
-export function makeObjectProxiedResult(
-  object: any,
-  errors: ReadonlyArray<GraphQLError>,
-  subschemas: Array<GraphQLSchema | SubschemaConfig>,
-) {
-  setErrors(object, errors.map(error => {
-    return relocatedError(
-      error,
-      error.nodes,
-      error.path ? error.path.slice(1) : undefined
-    );
-  }));
-  setSubschemas(object, subschemas);
-}
-
-export function handleObject(
-  type: GraphQLCompositeType,
-  object: any,
-  errors: ReadonlyArray<GraphQLError>,
-  subschemas: Array<GraphQLSchema | SubschemaConfig>,
-  context: Record<string, any>,
-  info: IGraphQLToolsResolveInfo,
-  skipTypeMerging?: boolean,
-) {
-  makeObjectProxiedResult(object, errors, subschemas);
-  if (skipTypeMerging || !info.mergeInfo) {
-    return object;
-  } else {
-    return mergeFields(
-      type,
-      object,
-      subschemas,
-      context,
-      info,
-    );
+    return handleList(type, result, errors, subschema, context, info, skipTypeMerging);
   }
 }
 
 function handleList(
   type: GraphQLList<any>,
   list: Array<any>,
   errors: ReadonlyArray<GraphQLError>,
-  subschemas: Array<GraphQLSchema | SubschemaConfig>,
+  subschema: GraphQLSchema | SubschemaConfig,
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
   skipTypeMerging?: boolean,
@@ -127,7 +91,7 @@ function handleList(
     listMember,
     index,
     childErrors[index] || [],
-    subschemas,
+    subschema,
     context,
     info,
     skipTypeMerging,
@@ -141,7 +105,7 @@ function handleListMember(
   listMember: any,
   index: number,
   errors: ReadonlyArray<GraphQLError>,
-  subschemas: Array<GraphQLSchema | SubschemaConfig>,
+  subschema: GraphQLSchema | SubschemaConfig,
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
   skipTypeMerging?: boolean,
@@ -153,56 +117,75 @@ function handleListMember(
   if (isLeafType(type)) {
     return type.parseValue(listMember);
   } else if (isCompositeType(type)) {
-    return handleObject(type, listMember, errors, subschemas, context, info, skipTypeMerging);
+    return handleObject(type, listMember, errors, subschema, context, info, skipTypeMerging);
   } else if (isListType(type)) {
-    return handleList(type, listMember, errors, subschemas, context, info, skipTypeMerging);
+    return handleList(type, listMember, errors, subschema, context, info, skipTypeMerging);
   }
 }
 
-function mergeFields(
+export function handleObject(
   type: GraphQLCompositeType,
   object: any,
-  subschemas: Array<GraphQLSchema | SubschemaConfig>,
+  errors: ReadonlyArray<GraphQLError>,
+  subschema: GraphQLSchema | SubschemaConfig,
   context: Record<string, any>,
   info: IGraphQLToolsResolveInfo,
-): any {
+  skipTypeMerging?: boolean,
+) {
+  setErrors(object, errors.map(error => {
+    return relocatedError(
+      error,
+      error.nodes,
+      error.path ? error.path.slice(1) : undefined
+    );
+  }));
+
+  setObjectSubschema(object, subschema);
+
+  if (skipTypeMerging || !info.mergeInfo) {
+    return object;
+  }
+
   let typeName: string;
   if (isAbstractType(type)) {
     typeName = info.schema.getTypeMap()[resolveFromParentTypename(object)].name;
   } else {
     typeName = type.name;
   }
 
-  const initialSchemas =
-    info.mergeInfo.mergedTypes[typeName] &&
-    info.mergeInfo.mergedTypes[typeName].subschemas;
-  if (initialSchemas) {
-    const remainingSubschemas = initialSchemas.filter(
-      subschema => !subschemas.includes(subschema)
-    );
-    if (remainingSubschemas.length) {
-      const maybePromises = remainingSubschemas.map(subschema => {
-        return subschema.mergedTypeConfigs[typeName].mergedTypeResolver(subschema, object, context, info);
-      });
+  const mergedTypeInfo = info.mergeInfo.mergedTypes[typeName];
+  let subschemas = mergedTypeInfo && mergedTypeInfo.subschemas;
 
-      let containsPromises = false; {
-        for (const maybePromise of maybePromises) {
-          if (maybePromise instanceof Promise) {
-            containsPromises = true;
-            break;
-          }
-        }
-      }
-      if (containsPromises) {
-        return Promise.all(maybePromises).
-          then(results => results.reduce((acc: any, r: ExecutionResult) => mergeDeep(acc, r), object));
-      } else {
-        return maybePromises.reduce((acc: any, r: ExecutionResult) => mergeDeep(acc, r), object);
-      }
-    }
+  if (!subschemas) {
+    return object;
   }
 
-  return object;
+  subschemas = subschemas.filter(s => s !== subschema);
+  if (!subschemas.length) {
+    return object;
+  }
+
+  const typeMap = isSubschemaConfig(subschema) ?
+    mergedTypeInfo.typeMaps.get(subschema) : subschema.getTypeMap();
+  const fields = (typeMap[typeName] as GraphQLObjectType).getFields();
+  const selections: Array<FieldNode> = [];
+  info.fieldNodes.forEach(fieldNode => {
+    collectFields(fieldNode.selectionSet, info.fragments).forEach(s => {
+      if (!fields[s.name.value]) {
+        selections.push(s);
+      }
+    });
+  });
+
+  return mergeFields(
+    mergedTypeInfo,
+    typeName,
+    object,
+    selections,
+    subschemas,
+    context,
+    info,
+  );
 }
 
 export function handleNull(

diff --git a/src/stitching/defaultMergedResolver.ts b/src/stitching/defaultMergedResolver.ts
@@ -1,5 +1,5 @@
 import { defaultFieldResolver } from 'graphql';
-import { getErrors, getSubschemas } from './proxiedResult';
+import { getErrors, getSubschema } from './proxiedResult';
 import { handleResult } from './checkResultAndHandleErrors';
 import { getResponseKeyFromInfo } from './getResponseKeyFromInfo';
 import { IGraphQLToolsResolveInfo } from '../Interfaces';
@@ -28,7 +28,7 @@ export default function defaultMergedResolver(
   }
 
   const result = parent[responseKey];
-  const subschemas = getSubschemas(parent);
+  const subschema = getSubschema(parent, responseKey);
 
-  return handleResult(result, errors, subschemas, context, info);
+  return handleResult(result, errors, subschema, context, info);
 }