Add the fetch response to the cache event payload.

Author: jaydenseric

changelog.md

@@ -2,6 +2,10 @@
 
 ## Next
 
+### Minor
+
+- Added a `response` property to the `GraphQL` instance `cache` event payload, containing the original `fetch` [`Response`](https://developer.mozilla.org/en-US/docs/Web/API/Response) instance the `cacheValue` was derived from.
+
 ### Patch
 
 - Updated dependencies.

src/test/GraphQL.mjs

@@ -48,6 +48,7 @@ t.test('GraphQL.operate()', async t => {
       }
     }),
     expectedResolvedCacheValue,
+    expectedResponseType = Response,
     callback
   }) => async t => {
     const fetchEvent = promisifyEvent(graphql, 'fetch')
@@ -125,6 +126,12 @@ t.test('GraphQL.operate()', async t => {
       'GraphQL `cache` event data property `cacheValue`'
     )
 
+    t.type(
+      cacheEventData.response,
+      expectedResponseType,
+      'GraphQL `cache` event data property `response`'
+    )
+
     if (resetEvent) {
       const resetEventData = await resetEvent
       t.equals(
@@ -193,7 +200,8 @@ t.test('GraphQL.operate()', async t => {
         port,
         expectedResolvedCacheValue: {
           fetchError: 'Global fetch API or polyfill unavailable.'
-        }
+        },
+        expectedResponseType: 'undefined'
       })
     )
 

src/universal/GraphQL.mjs

@@ -131,6 +131,8 @@ export class GraphQL {
    * @ignore
    */
   fetch = ({ url, ...options }, cacheKey) => {
+    let fetchResponse
+
     const fetcher =
       typeof fetch === 'function'
         ? fetch
@@ -142,6 +144,8 @@ export class GraphQL {
     const cacheValuePromise = fetcher(url, options)
       .then(
         response => {
+          fetchResponse = response
+
           if (!response.ok)
             cacheValue.httpError = {
               status: response.status,
@@ -172,7 +176,13 @@ export class GraphQL {
         // Clear the loaded operation.
         delete this.operations[cacheKey]
 
-        this.emit('cache', { cacheKey, cacheValue })
+        this.emit('cache', {
+          cacheKey,
+          cacheValue,
+
+          // May be undefined if there was a fetch error.
+          response: fetchResponse
+        })
 
         return cacheValue
       })