add batchDelegate package

Add key option within type merging config to enable batch loading for lists. This minimal version of batching uses cached dataLoaders to create a separate batch for each list rather than for every similar query within the resolution tree. This is because a new dataloader is created for every new info.fieldNodes object, which is memoized upstream by graphql-js within resolution of a given list to allow the loader to be used for items of that list. A future version could provide an option to batch by similar target fieldName/selectionSet, but this version may hit the sweet spot in terms of code complexity and batching behavior. see: #1710
ardatan · Jul 8, 2020 · 59b5606 · 59b5606
1 parent 70443c8
commit 59b5606
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Showing 10 changed files with 167 additions and 27 deletions.
diff --git a/packages/batchDelegate/package.json b/packages/batchDelegate/package.json
@@ -0,0 +1,34 @@
+{
+  "name": "@graphql-tools/batchDelegate",
+  "version": "6.0.12",
+  "description": "A set of utils for faster development of GraphQL tools",
+  "repository": "git@github.com:ardatan/graphql-tools.git",
+  "license": "MIT",
+  "sideEffects": false,
+  "main": "dist/index.cjs.js",
+  "module": "dist/index.esm.js",
+  "typings": "dist/index.d.ts",
+  "typescript": {
+    "definition": "dist/index.d.ts"
+  },
+  "peerDependencies": {
+    "graphql": "^14.0.0 || ^15.0.0"
+  },
+  "buildOptions": {
+    "input": "./src/index.ts"
+  },
+  "dependencies": {
+    "@graphql-tools/delegate": "6.0.12",
+    "dataloader": "2.0.0",
+    "tslib": "~2.0.0"
+  },
+  "devDependencies": {
+    "@graphql-tools/schema": "6.0.12",
+    "@graphql-tools/stitch": "6.0.12",
+    "@graphql-tools/utils": "6.0.12"
+  },
+  "publishConfig": {
+    "access": "public",
+    "directory": "dist"
+  }
+}
diff --git a/packages/batchDelegate/src/createBatchDelegateFn.ts b/packages/batchDelegate/src/createBatchDelegateFn.ts
@@ -0,0 +1,51 @@
+import { FieldNode, getNamedType, GraphQLOutputType, GraphQLList } from 'graphql';
+
+import DataLoader from 'dataloader';
+
+import { delegateToSchema } from '@graphql-tools/delegate';
+
+import { BatchDelegateOptionsFn, BatchDelegateFn, BatchDelegateOptions } from './types';
+
+export function createBatchDelegateFn<K = any, V = any, C = K>(
+  argFn: (args: ReadonlyArray<K>) => Record<string, any>,
+  batchDelegateOptionsFn: BatchDelegateOptionsFn,
+  dataLoaderOptions?: DataLoader.Options<K, V, C>
+): BatchDelegateFn<K> {
+  let cache: WeakMap<ReadonlyArray<FieldNode>, DataLoader<K, V, C>>;
+
+  function createBatchFn(options: BatchDelegateOptions) {
+    return async (keys: ReadonlyArray<K>) => {
+      const results = await delegateToSchema({
+        returnType: new GraphQLList(getNamedType(options.info.returnType) as GraphQLOutputType),
+        args: argFn(keys),
+        ...batchDelegateOptionsFn(options),
+      });
+      return Array.isArray(results) ? results : keys.map(() => results);
+    };
+  }
+
+  function getLoader(options: BatchDelegateOptions) {
+    if (!cache) {
+      cache = new WeakMap();
+      const batchFn = createBatchFn(options);
+      const newValue = new DataLoader<K, V, C>(keys => batchFn(keys), dataLoaderOptions);
+      cache.set(options.info.fieldNodes, newValue);
+      return newValue;
+    }
+
+    const cachedValue = cache.get(options.info.fieldNodes);
+    if (cachedValue === undefined) {
+      const batchFn = createBatchFn(options);
+      const newValue = new DataLoader<K, V, C>(keys => batchFn(keys), dataLoaderOptions);
+      cache.set(options.info.fieldNodes, newValue);
+      return newValue;
+    }
+
+    return cachedValue;
+  }
+
+  return options => {
+    const loader = getLoader(options);
+    return loader.load(options.key);
+  };
+}
diff --git a/packages/batchDelegate/src/index.ts b/packages/batchDelegate/src/index.ts
@@ -0,0 +1,3 @@
+export { createBatchDelegateFn } from './createBatchDelegateFn';
+
+export * from './types';
diff --git a/packages/batchDelegate/src/types.ts b/packages/batchDelegate/src/types.ts
@@ -0,0 +1,14 @@
+import { IDelegateToSchemaOptions } from '@graphql-tools/delegate';
+
+export type BatchDelegateFn<TContext = Record<string, any>, K = any> = (
+  batchDelegateOptions: BatchDelegateOptions<TContext, K>
+) => any;
+
+export type BatchDelegateOptionsFn<TContext = Record<string, any>, K = any> = (
+  batchDelegateOptions: BatchDelegateOptions<TContext, K>
+) => IDelegateToSchemaOptions<TContext>;
+
+export interface BatchDelegateOptions<TContext = Record<string, any>, K = any>
+  extends Omit<IDelegateToSchemaOptions<TContext>, 'args'> {
+  key: K;
+}
diff --git a/.../stitch/tests/typeMerging.example.test.ts → ...elegate/tests/typeMerging.example.test.ts b/.../stitch/tests/typeMerging.example.test.ts → ...elegate/tests/typeMerging.example.test.ts
@@ -1,16 +1,16 @@
-// Conversion of Apollo Federation demo from https://github.com/apollographql/federation-demo.
-// See: https://github.com/ardatan/graphql-tools/issues/1697
+// Conversion of Apollo Federation demo
+// Compare: https://github.com/apollographql/federation-demo
+// See also:
+// https://github.com/ardatan/graphql-tools/issues/1697
+// https://github.com/ardatan/graphql-tools/issues/1710
 
 import { graphql } from 'graphql';
 
 import { makeExecutableSchema } from '@graphql-tools/schema';
-
 import { ExecutionResult } from '@graphql-tools/utils';
-
-import { stitchSchemas } from '../src/stitchSchemas';
+import { stitchSchemas } from '@graphql-tools/stitch';
 
 describe('merging using type merging', () => {
-
   const users = [
     {
       id: '1',
@@ -31,6 +31,7 @@ describe('merging using type merging', () => {
       type Query {
         me: User
         _userById(id: ID!): User
+        _usersById(ids: [ID!]!): [User]
       }
       type User {
         id: ID!
@@ -42,6 +43,7 @@ describe('merging using type merging', () => {
       Query: {
         me: () => users[0],
         _userById: (_root, { id }) => users.find(user => user.id === id),
+        _usersById: (_root, { ids }) => ids.map((id: any) => users.find(user => user.id === id)),
       },
     },
   });
@@ -111,6 +113,7 @@ describe('merging using type merging', () => {
       type Query {
         topProducts(first: Int = 5): [Product]
         _productByUpc(upc: String!): Product
+        _productsByUpc(upcs: [String!]!): [Product]
       }
       type Product {
         upc: String!
@@ -123,6 +126,7 @@ describe('merging using type merging', () => {
       Query: {
         topProducts: (_root, args) => products.slice(0, args.first),
         _productByUpc: (_root, { upc }) => products.find(product => product.upc === upc),
+        _productsByUpc: (_root, { upcs }) => upcs.map((upc: any) => products.find(product => product.upc === upc)),
       }
     },
   });
@@ -179,8 +183,10 @@ describe('merging using type merging', () => {
       }
       type Query {
         _userById(id: ID!): User
+        _usersById(ids: [ID!]!): [User]
         _reviewById(id: ID!): Review
         _productByUpc(upc: String!): Product
+        _productsByUpc(upcs: [String!]!): [Product]
       }
     `,
     resolvers: {
@@ -201,7 +207,9 @@ describe('merging using type merging', () => {
       Query: {
         _reviewById: (_root, { id }) => reviews.find(review => review.id === id),
         _userById: (_root, { id }) => ({ id }),
+        _usersById: (_root, { ids }) => ids.map((id: string) => ({ id })),
         _productByUpc: (_, { upc }) => ({ upc }),
+        _productsByUpc: (_, { upcs }) => upcs.map((upc: string) => ({ upc })),
       },
     }
   });
@@ -212,8 +220,8 @@ describe('merging using type merging', () => {
         schema: accountsSchema,
         merge: {
           User: {
-            fieldName: '_userById',
             selectionSet: '{ id }',
+            fieldName: '_userById',
             args: ({ id }) => ({ id })
           }
         }
@@ -222,8 +230,8 @@ describe('merging using type merging', () => {
         schema: inventorySchema,
         merge: {
           Product: {
-            fieldName: '_productByUpc',
             selectionSet: '{ upc weight price }',
+            fieldName: '_productByUpc',
             args: ({ upc, weight, price }) => ({ upc, weight, price }),
           }
         }
@@ -232,8 +240,8 @@ describe('merging using type merging', () => {
         schema: productsSchema,
         merge: {
           Product: {
-            fieldName: '_productByUpc',
             selectionSet: '{ upc }',
+            fieldName: '_productByUpc',
             args: ({ upc }) => ({ upc }),
           }
         }
@@ -242,13 +250,14 @@ describe('merging using type merging', () => {
         schema: reviewsSchema,
         merge: {
           User: {
-            fieldName: '_userById',
             selectionSet: '{ id }',
-            args: ({ id }) => ({ id }),
+            fieldName: '_usersById',
+            args: (ids) => ({ ids }),
+            key: ({ id }) => id,
           },
           Product: {
-            fieldName: '_productByUpc',
             selectionSet: '{ upc }',
+            fieldName: '_productByUpc',
             args: ({ upc }) => ({ upc }),
           },
         }

diff --git a/packages/delegate/src/types.ts b/packages/delegate/src/types.ts
@@ -135,7 +135,8 @@ export interface SubschemaConfig {
 export interface MergedTypeConfig {
   selectionSet?: string;
   fieldName?: string;
-  args?: (originalResult: any) => Record<string, any>;
+  args?: (source: any) => Record<string, any>;
+  key?: (originalResult: any) => any;
   resolve?: MergedTypeResolver;
 }
 

diff --git a/packages/graphql-tools/package.json b/packages/graphql-tools/package.json
@@ -19,6 +19,7 @@
     "directory": "dist"
   },
   "dependencies": {
+    "@graphql-tools/batchDelegate": "6.0.12",
     "@graphql-tools/delegate": "6.0.12",
     "@graphql-tools/graphql-tag-pluck": "6.0.12",
     "@graphql-tools/import": "6.0.12",
@@ -41,4 +42,4 @@
     "@graphql-tools/utils": "6.0.12",
     "@graphql-tools/wrap": "6.0.12"
   }
-}
+}
diff --git a/packages/graphql-tools/src/index.ts b/packages/graphql-tools/src/index.ts
@@ -1,3 +1,4 @@
+export * from '@graphql-tools/batchDelegate';
 export * from '@graphql-tools/delegate';
 export * from '@graphql-tools/graphql-tag-pluck';
 export * from '@graphql-tools/import';

diff --git a/packages/stitch/package.json b/packages/stitch/package.json
@@ -21,6 +21,7 @@
     "dataloader": "2.0.0"
   },
   "dependencies": {
+    "@graphql-tools/batchDelegate": "6.0.12",
     "@graphql-tools/delegate": "6.0.12",
     "@graphql-tools/merge": "6.0.12",
     "@graphql-tools/schema": "6.0.12",
@@ -32,4 +33,4 @@
     "access": "public",
     "directory": "dist"
   }
-}
+}
diff --git a/packages/stitch/src/stitchingInfo.ts b/packages/stitch/src/stitchingInfo.ts
@@ -21,6 +21,7 @@ import {
 } from '@graphql-tools/utils';
 
 import { delegateToSchema, isSubschemaConfig, SubschemaConfig } from '@graphql-tools/delegate';
+import { createBatchDelegateFn } from '@graphql-tools/batchDelegate';
 
 import { MergeTypeCandidate, MergedTypeInfo, StitchingInfo, MergeTypeFilter } from './types';
 
@@ -103,18 +104,42 @@ function createMergedTypes(
           }
 
           if (!mergedTypeConfig.resolve) {
-            mergedTypeConfig.resolve = (originalResult, context, info, subschema, selectionSet) =>
-              delegateToSchema({
-                schema: subschema,
-                operation: 'query',
-                fieldName: mergedTypeConfig.fieldName,
-                returnType: getNamedType(info.returnType) as GraphQLOutputType,
-                args: mergedTypeConfig.args(originalResult),
-                selectionSet,
-                context,
-                info,
-                skipTypeMerging: true,
-              });
+            if (mergedTypeConfig.key != null) {
+              const batchDelegateToSubschema = createBatchDelegateFn(
+                mergedTypeConfig.args,
+                ({ schema, selectionSet, context, info }) => ({
+                  schema,
+                  operation: 'query',
+                  fieldName: mergedTypeConfig.fieldName,
+                  selectionSet,
+                  context,
+                  info,
+                  skipTypeMerging: true,
+                })
+              );
+
+              mergedTypeConfig.resolve = (originalResult, context, info, subschema, selectionSet) =>
+                batchDelegateToSubschema({
+                  key: mergedTypeConfig.key(originalResult),
+                  schema: subschema,
+                  context,
+                  info,
+                  selectionSet,
+                });
+            } else {
+              mergedTypeConfig.resolve = (originalResult, context, info, subschema, selectionSet) =>
+                delegateToSchema({
+                  schema: subschema,
+                  operation: 'query',
+                  fieldName: mergedTypeConfig.fieldName,
+                  returnType: getNamedType(info.returnType) as GraphQLOutputType,
+                  args: mergedTypeConfig.args(originalResult),
+                  selectionSet,
+                  context,
+                  info,
+                  skipTypeMerging: true,
+                });
+            }
           }
 
           subschemas.push(subschemaConfig);