feat: add skipBatch to cacheConfig options for batchMiddleware (#100)

When `cacheConfig.skipBatch` is truthy, we skip batching for that
request even when the batchMiddleware is present. This allows users to
better control what requests are batched together.

src/__mocks__/mockReq.js

@@ -3,10 +3,12 @@
 
 import type RelayNetworkLayer from '../RelayNetworkLayer';
 import type RelayResponse from '../RelayResponse';
+import type { CacheConfig } from '../definition';
 
 type ReqData = {
   query?: string,
   variables?: Object,
+  cacheConfig?: CacheConfig,
   files?: any,
 };
 
@@ -17,6 +19,7 @@ class MockReq {
   reqData: ReqData;
   error: Error;
   payload: Object;
+  cacheConfig: Object;
 
   constructor(reqid?: ReqId, reqData?: ReqData = {}) {
     this.reqid = reqid || Math.random().toString();
@@ -60,7 +63,7 @@ class MockReq {
       operationKind,
     }: any);
     const variables = this.getVariables() || {};
-    const cacheConfig = {};
+    const cacheConfig = this.reqData.cacheConfig || {};
     const uploadables = this.getFiles();
 
     const res = (rnl.fetchFn(operation, variables, cacheConfig, uploadables): any);

src/definition.js

@@ -88,6 +88,7 @@ export type CacheConfig = {
   force?: ?boolean,
   poll?: ?number,
   rerunParamExperimental?: ?any,
+  skipBatch?: ?boolean,
 };
 export type Disposable = { dispose(): void };
 export type Uploadable = File | Blob;

src/middlewares/__tests__/batch-test.js

@@ -215,6 +215,39 @@ describe('middlewares/batch', () => {
     expect(fetchMock.lastOptions()).toMatchSnapshot();
   });
 
+  it('should not batch requests cacheConfig `skipBatch=true`', async () => {
+    fetchMock.mock({
+      matcher: '/graphql',
+      response: {
+        status: 200,
+        body: { data: { ok: 1 } },
+      },
+      method: 'POST',
+    });
+
+    fetchMock.mock({
+      matcher: '/graphql/batch',
+      response: {
+        status: 200,
+        body: [{ data: { ok: 2 } }, { data: { ok: 3 } }],
+      },
+      method: 'POST',
+    });
+
+    const rnl = new RelayNetworkLayer([batchMiddleware()]);
+    const req1 = mockReq(1, { cacheConfig: { skipBatch: true } });
+    const req2 = mockReq(2);
+    const req3 = mockReq(3);
+    const [res1, res2, res3] = await Promise.all([
+      req1.execute(rnl),
+      req2.execute(rnl),
+      req3.execute(rnl),
+    ]);
+    expect(res1.data).toEqual({ ok: 1 });
+    expect(res2.data).toEqual({ ok: 2 });
+    expect(res3.data).toEqual({ ok: 3 });
+  });
+
   describe('option `batchTimeout`', () => {
     beforeEach(() => {
       fetchMock.restore();

src/middlewares/batch.js

@@ -84,6 +84,11 @@ export default function batchMiddleware(options?: BatchMiddlewareOpts): Middlewa
       return next(req);
     }
 
+    // skip batching if request explicitly opts out
+    if (req.cacheConfig.skipBatch) {
+      return next(req);
+    }
+
     return passThroughBatch(req, next, {
       batchTimeout,
       batchUrl,