Optionally disable incremental responses (#6)

* fix snaps

* add applyToPrevious options

Author: robrichard

src/PatchResolver.js

@@ -35,7 +35,8 @@ function mergeErrors(previousErrors, patchErrors) {
     return undefined;
 }
 
-export function PatchResolver({ onResponse, mergeExtensions = () => {} }) {
+export function PatchResolver({ onResponse, applyToPrevious, mergeExtensions = () => {} }) {
+    this.applyToPrevious = typeof applyToPrevious === 'boolean' ? applyToPrevious : true;
     this.onResponse = onResponse;
     this.mergeExtensions = mergeExtensions;
     this.previousResponse = null;
@@ -48,23 +49,27 @@ PatchResolver.prototype.handleChunk = function(data) {
     const { newBuffer, parts } = parseMultipartHttp(this.chunkBuffer);
     this.chunkBuffer = newBuffer;
     if (parts.length) {
-        parts.forEach(part => {
-            if (this.processedChunks === 0) {
-                this.previousResponse = part;
-            } else {
-                if (!(Array.isArray(part.path) && typeof part.data !== 'undefined')) {
-                    throw new Error('invalid patch format ' + JSON.stringify(part, null, 2));
+        if (this.applyToPrevious) {
+            parts.forEach(part => {
+                if (this.processedChunks === 0) {
+                    this.previousResponse = part;
+                } else {
+                    if (!(Array.isArray(part.path) && typeof part.data !== 'undefined')) {
+                        throw new Error('invalid patch format ' + JSON.stringify(part, null, 2));
+                    }
+                    this.previousResponse = {
+                        ...this.previousResponse,
+                        data: applyPatch(this.previousResponse.data, part.path, part.data),
+                        errors: mergeErrors(this.previousResponse.errors, part.errors),
+                        extensions: this.mergeExtensions(this.previousResponse.extensions, part.extensions),
+                    };
                 }
-                this.previousResponse = {
-                    ...this.previousResponse,
-                    data: applyPatch(this.previousResponse.data, part.path, part.data),
-                    errors: mergeErrors(this.previousResponse.errors, part.errors),
-                    extensions: this.mergeExtensions(this.previousResponse.extensions, part.extensions),
-                };
-            }
-            this.processedChunks += 1;
-        });
-        // don't need to re-trigger every intermediate state
-        this.onResponse(this.previousResponse);
+                this.processedChunks += 1;
+            });
+            // don't need to re-trigger every intermediate state
+            this.onResponse(this.previousResponse);
+        } else {
+            parts.forEach(part => this.onResponse(part));
+        }
     }
 };

src/__test__/PatchResolver.spec.js

@@ -183,4 +183,21 @@ describe('PathResolver', function() {
         resolver.handleChunk(chunk3);
         expect(onResponse.mock.calls[0][0]).toMatchSnapshot();
     });
+
+    it('should work when not applying to previous', function() {
+        const onResponse = jest.fn();
+        const resolver = new PatchResolver({
+            onResponse,
+            applyToPrevious: false,
+        });
+
+        const chunk2a = chunk2.substring(0, 35);
+        const chunk2b = chunk2.substring(35);
+
+        resolver.handleChunk(chunk1 + chunk2a);
+        expect(onResponse.mock.calls[0][0]).toMatchSnapshot();
+        onResponse.mockClear();
+        resolver.handleChunk(chunk2b);
+        expect(onResponse.mock.calls[0][0]).toMatchSnapshot();
+    });
 });

src/__test__/__snapshots__/PatchResolver.spec.js.snap

@@ -44,6 +44,7 @@ Object {
       "message": "Not So Bad Error",
     },
   ],
+  "extensions": undefined,
 }
 `;
 
@@ -75,6 +76,7 @@ Object {
       "message": "Not So Bad Error",
     },
   ],
+  "extensions": undefined,
 }
 `;
 
@@ -138,6 +140,7 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
 }
 `;
 
@@ -176,6 +179,7 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
 }
 `;
 
@@ -214,6 +218,7 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
 }
 `;
 
@@ -250,6 +255,7 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
 }
 `;
 
@@ -313,6 +319,7 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
 }
 `;
 
@@ -349,6 +356,7 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
 }
 `;
 
@@ -387,6 +395,7 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
 }
 `;
 
@@ -450,6 +459,7 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
 }
 `;
 
@@ -488,5 +498,51 @@ Object {
     },
   },
   "errors": undefined,
+  "extensions": undefined,
+}
+`;
+
+exports[`PathResolver should work when not applying to previous 1`] = `
+Object {
+  "data": Object {
+    "viewer": Object {
+      "currencies": null,
+      "user": Object {
+        "items": Object {
+          "edges": Array [
+            Object {
+              "node": Object {
+                "isFavorite": null,
+              },
+            },
+            Object {
+              "node": Object {
+                "isFavorite": null,
+              },
+            },
+          ],
+        },
+        "profile": null,
+      },
+    },
+  },
+}
+`;
+
+exports[`PathResolver should work when not applying to previous 2`] = `
+Object {
+  "data": Array [
+    "USD",
+    "GBP",
+    "EUR",
+    "CAD",
+    "AUD",
+    "CHF",
+    "😂",
+  ],
+  "path": Array [
+    "viewer",
+    "currencies",
+  ],
 }
 `;

src/fetch.js

@@ -1,6 +1,6 @@
 import { PatchResolver } from './PatchResolver';
 
-export function fetchImpl(url, { method, headers, credentials, body, onNext, onError, onComplete }) {
+export function fetchImpl(url, { method, headers, credentials, body, onNext, onError, onComplete, applyToPrevious }) {
     return fetch(url, { method, headers, body, credentials }).then(response => {
         // @defer uses multipart responses to stream patches over HTTP
         if (
@@ -12,7 +12,7 @@ export function fetchImpl(url, { method, headers, credentials, body, onNext, onE
             // For the majority of browsers with support for ReadableStream and TextDecoder
             const reader = response.body.getReader();
             const textDecoder = new TextDecoder();
-            const patchResolver = new PatchResolver({ onResponse: r => onNext(r) });
+            const patchResolver = new PatchResolver({ onResponse: r => onNext(r), applyToPrevious });
             return reader.read().then(function sendNext({ value, done }) {
                 if (!done) {
                     let plaintext;

src/xhr.js

@@ -11,13 +11,13 @@ function supportsXhrResponseType(type) {
     return false;
 }
 
-export function xhrImpl(url, { method, headers, credentials, body, onNext, onError, onComplete }) {
+export function xhrImpl(url, { method, headers, credentials, body, onNext, onError, onComplete, applyToPrevious }) {
     const xhr = new XMLHttpRequest();
     xhr.withCredentials = credentials === 'include'; // follow behavior of fetch credentials param https://github.com/github/fetch#sending-cookies
     let index = 0;
     let isDeferred = false;
 
-    const patchResolver = new PatchResolver({ onResponse: r => onNext(r) });
+    const patchResolver = new PatchResolver({ onResponse: r => onNext(r), applyToPrevious });
 
     function onReadyStateChange() {
         // The request failed, do nothing and let the error event fire