Update saga middleware options to reflect implementation (#2372)

We already allowed `channel` to be passed into `createSagaMiddleware`,
this change simply updates our types to match our implementation.

I also added a recipe for batching redux actions since it is a very
common paradigm and something I've had to re-write multiple times from
memory.

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

.changeset/eighty-lions-sleep.md

@@ -0,0 +1,6 @@
+---
+'@redux-saga/core': patch
+'redux-saga': patch
+---
+
+Added a `channel` property to the `SagaMiddlewareOptions` to reflect its runtime support.

docs/API.md

@@ -19,7 +19,8 @@ Creates a Redux middleware and connects the Sagas to the Redux Store
 
   - `onError: (error: Error, { sagaStack: string })` - if provided, the middleware will call it with uncaught errors from Sagas. useful for sending uncaught exceptions to error tracking services.
   - `effectMiddlewares` : Function [] - allows you to intercept any effect, resolve it on your own and pass to the next middleware. See [this section](advanced/Testing.md#effectmiddlewares) for a detailed example
-
+  - `channel`: If provided, the middleware will use this channel instead of the default `stdChannel()` for
+   * `take` and `put` effects.
 
 #### Example
 

docs/Recipes.md

@@ -214,3 +214,46 @@ function* main() {
   }
 }
 ```
+
+## Batching actions
+
+`redux` does not support the ability to dispatch multiple actions and only call
+the reducer once.  This has performance implications and the ergonomics of
+needing to dispatch multiple actions sequentially aren't great.
+
+Instead we look to a third-party library, [redux-batched-actions](https://github.com/tshelburne/redux-batched-actions).  This is a
+simple reducer and action that allows end-developers to dispatch multiple
+actions and only have your reducer be called once.
+
+If you have a codebase that needs to dispatch many actions at the same time, we
+recommend using this recipe.
+
+```javascript
+import { configureStore } from '@reduxjs/toolkit';
+import createSagaMiddleware, { stdChannel } from 'redux-saga';
+import { enableBatching, BATCH } from 'redux-batched-actions';
+
+// your root reducer
+import { rootReducer } from './reducer';
+// your root saga
+import { rootSaga } from './saga';
+
+const channel = stdChannel();
+const rawPut = channel.put;
+channel.put = (action: ActionWithPayload<any>) => {
+  if (action.type === BATCH) {
+    action.payload.forEach(rawPut);
+    return;
+  }
+  rawPut(action);
+};
+const sagaMiddleware = createSagaMiddleware({ channel });
+
+const reducer = enableBatching(rootReducer);
+// https://redux-toolkit.js.org/api/configureStore
+const store = configureStore({
+  reducer: rootReducer,
+  middleware: [sagaMiddleware],
+});
+sagaMiddleware.run(rootSaga);
+```

packages/core/types/index.d.ts

@@ -125,6 +125,11 @@ export interface SagaMiddlewareOptions<C extends object = {}> {
    * next middleware.
    */
   effectMiddlewares?: EffectMiddleware[]
+  /**
+   * If provided, the middleware will use this channel instead of the default `stdChannel` for
+   * take and put effects.
+   */
+  channel?: MulticastChannel<Action>;
 }
 
 export interface SagaMiddleware<C extends object = {}> extends Middleware {

packages/core/types/ts3.6/index.d.ts

@@ -124,6 +124,11 @@ export interface SagaMiddlewareOptions<C extends object = {}> {
    * next middleware.
    */
   effectMiddlewares?: EffectMiddleware[]
+  /**
+   * If provided, the middleware will use this channel instead of the default `stdChannel` for
+   * take and put effects.
+   */
+  channel?: MulticastChannel<Action>;
 }
 
 export interface SagaMiddleware<C extends object = {}> extends Middleware {