feat(persisted-fetch): Add enableForMutation option

.changeset/slimy-nails-complain.md

@@ -0,0 +1,5 @@
+---
+'@urql/exchange-persisted-fetch': minor
+---
+
+Adds enableForMutation option for exchange-persisted-fetch to enable persisted operations for mutations

docs/api/persisted-fetch-exchange.md

@@ -65,3 +65,4 @@ const client = createClient({
 | `preferGetForPersistedQueries` | This is similar to [the `Client`'s `preferGetMethod` option](./core.md#client) and will cause all persisted queries to be sent using a GET request.                                                                                                                                                                      |
 | `enforcePersistedQueries`      | This option enforced persisted queries. Instead of allowing automatic persisted queries or triggering any retry logic when the API responds, it instead assumes that persisted queries will succeed and run like normal GraphQL API requests.                                                                            |
 | `generateHash`                 | This option accepts a function that receives the `query` as a string and the raw `DocumentNode` as a second argument and must return a `Promise<string>` resolving to a SHA256 hash. This can be used to swap out the SHA256 API, e.g. for React Native, or to use pre-generated SHA256 strings from the `DocumentNode`. |
+| `enableForMutation`            | This option allows mutations to be persisted in addition to queries. It's false by default. When a persisted mutation is requested, `preferGetForPersistedQueries` will be ignored and a POST method will always be used.                                                                                                |

exchanges/persisted-fetch/src/persistedFetchExchange.ts

@@ -36,6 +36,7 @@ interface PersistedFetchExchangeOptions {
   preferGetForPersistedQueries?: boolean;
   enforcePersistedQueries?: boolean;
   generateHash?: (query: string, document: DocumentNode) => Promise<string>;
+  enableForMutation?: boolean;
 }
 
 export const persistedFetchExchange = (
@@ -46,13 +47,18 @@ export const persistedFetchExchange = (
   const preferGetForPersistedQueries = !!options.preferGetForPersistedQueries;
   const enforcePersistedQueries = !!options.enforcePersistedQueries;
   const hashFn = options.generateHash || hash;
+  const enableForMutation = options.enableForMutation || false;
   let supportsPersistedQueries = true;
 
+  const operationFilter = (operation: Operation) =>
+    (enableForMutation && operation.kind === 'mutation') ||
+    operation.kind === 'query';
+
   return ops$ => {
     const sharedOps$ = share(ops$);
     const fetchResults$ = pipe(
       sharedOps$,
-      filter(operation => operation.kind === 'query'),
+      filter(operationFilter),
       mergeMap(operation => {
         const { key } = operation;
         const teardown$ = pipe(
@@ -86,11 +92,15 @@ export const persistedFetchExchange = (
                 },
               };
             }
+            const useGet =
+              operation.kind === 'query' &&
+              preferGetForPersistedQueries &&
+              !!sha256Hash;
             return makePersistedFetchSource(
               operation,
               body,
               dispatchDebug,
-              !!(preferGetForPersistedQueries && sha256Hash)
+              useGet
             );
           }),
           mergeMap(result => {
@@ -128,7 +138,7 @@ export const persistedFetchExchange = (
 
     const forward$ = pipe(
       sharedOps$,
-      filter(operation => operation.kind !== 'query'),
+      filter(operation => !operationFilter(operation)),
       forward
     );