Merge pull request reduxjs#44 from emmenko/read-state-by-store

Allow to read state by store on action creator callback

Author: gaearon

README.md

@@ -62,10 +62,10 @@ export function incrementAsync() {
   };
 }
 
-// Could also look into state in the callback form
+// Could also read state of a store in the callback form
 export function incrementIfOdd() {
-  return (dispatch, state) => {
-    if (state.counterStore % 2 === 0) {
+  return (dispatch, read) => {
+    if (read(counterStore) % 2 === 0) {
       return;
     }
 

examples/counter/actions/CounterActions.js

@@ -2,6 +2,7 @@ import {
   INCREMENT_COUNTER,
   DECREMENT_COUNTER
 } from '../constants/ActionTypes';
+import { counterStore } from '../stores';
 
 export function increment() {
   return {
@@ -10,8 +11,8 @@ export function increment() {
 }
 
 export function incrementIfOdd() {
-  return (dispatch, state) => {
-    if (state.counterStore.counter % 2 === 0) {
+  return (dispatch, read) => {
+    if (read(counterStore) % 2 === 0) {
       return;
     }
 

src/createDispatcher.js

@@ -121,14 +121,19 @@ export default function createDispatcher() {
       const action = actionCreator(...args);
       if (typeof action === 'function') {
         // Callback-style action creator
-        action(dispatch, currentState);
+        action(dispatch, read);
       } else {
         // Simple action creator
         dispatch(action);
       }
     };
   }
 
+  // Allow to read the state of a store
+  function read(store) {
+    return currentState[getStoreKey(store)];
+  }
+
   return {
     wrapActionCreator,
     observeStores,