Pass parent props into mapStateToProps

Addresses part of reduxjs#52 by passing the parent props into mapStateWithProps.

README.md

@@ -4,7 +4,7 @@ React Redux
 Official React bindings for [Redux](https://github.com/gaearon/redux).  
 Performant and flexible.
 
-[![npm version](https://img.shields.io/npm/v/react-redux.svg?style=flat-square)](https://www.npmjs.com/package/react-redux) 
+[![npm version](https://img.shields.io/npm/v/react-redux.svg?style=flat-square)](https://www.npmjs.com/package/react-redux)
 [![npm downloads](https://img.shields.io/npm/dm/react-redux.svg?style=flat-square)](https://www.npmjs.com/package/react-redux)
 [![redux channel on slack](https://img.shields.io/badge/slack-redux@reactiflux-61DAFB.svg?style=flat-square)](http://www.reactiflux.com)
 
@@ -226,7 +226,7 @@ Connects a React component to a Redux store.
 
 #### Arguments
 
-* [`mapStateToProps(state): stateProps`] \(*Function*): If specified, the component will subscribe to Redux store updates. Any time it updates, `mapStateToProps` will be called. Its result must be a plain object, and it will be merged into the component’s props. If you omit it, the component will not be subscribed to the Redux store.
+* [`mapStateToProps(state, props): stateProps`] \(*Function*): If specified, the component will subscribe to Redux store updates. Any time the store updates or the component receives new props, `mapStateToProps` will be called. Its result must be a plain object, and it will be merged into the component’s props. If you omit it, the component will not be subscribed to the Redux store.
 
 * [`mapDispatchToProps(dispatch): dispatchProps`] \(*Object* or *Function*): If an object is passed, each function inside it will be assumed to be a Redux action creator. An object with the same function names, but bound to a Redux store, will be merged into the component’s props. If a function is passed, it will be given `dispatch`. It’s up to you to return an object that somehow uses `dispatch` to bind action creators in your own way. (Tip: you may use [`bindActionCreators()`](http://gaearon.github.io/redux/docs/api/bindActionCreators.html) helper from Redux.) If you omit it, the default implementation just injects `dispatch` into your component’s props.
 
@@ -240,7 +240,7 @@ A React component class that injects state and action creators into your compone
 
 * It needs to be invoked two times. First time with its arguments described above, and second time, with the component: `connect(mapStateToProps, mapDispatchToProps, mergeProps)(MyComponent)`.
 
-* The `mapStateToProps` function takes a single argument of the entire Redux store’s state and returns an object to be passed as props. It is often called a **selector**. Use [reselect](https://github.com/faassen/reselect) to efficiently compose selectors and [compute derived data](http://gaearon.github.io/redux/docs/recipes/ComputingDerivedData.html).
+* The `mapStateToProps` function takes the entire Redux store’s state and the "smart" component's props and returns an object to be passed as props. It is often called a **selector**. Use [reselect](https://github.com/faassen/reselect) to efficiently compose selectors and [compute derived data](http://gaearon.github.io/redux/docs/recipes/ComputingDerivedData.html).
 
 * **To use `connect()`, the root component of your app must be wrapped into `<Provider>{() => ... }</Provider>` before being rendered.** You may also pass `store` as a prop to the `connect()`ed component, but it's not recommended because it's just too much trouble. Only do this for in non-fully-React codebases or to stub store in a unit test.
 
@@ -398,7 +398,7 @@ Make sure to check out [Troubleshooting Redux](http://gaearon.github.io/redux/do
 ### My views aren’t updating!
 
 See the link above.
-In short, 
+In short,
 
 * Reducers should never mutate state, they must return new objects, or React Redux won’t see the updates.
 * Make sure you either bind action creators with `mapDispatchToState` argument to `connect()` or with `bindActionCreators()` method, or that you manually call `dispatch()`. Just calling your `MyActionCreators.addTodo()` function won’t work because it just *returns* an action, but not *dispatches* it.

src/components/createConnect.js

@@ -26,6 +26,7 @@ export default function createConnect(React) {
   return function connect(mapStateToProps, mapDispatchToProps, mergeProps) {
     const shouldSubscribe = Boolean(mapStateToProps);
     const finalMapStateToProps = mapStateToProps || defaultMapStateToProps;
+    const statePropsDependOnParentProps = finalMapStateToProps.length > 1;
     const finalMapDispatchToProps = isPlainObject(mapDispatchToProps) ?
       wrapActionCreators(mapDispatchToProps) :
       mapDispatchToProps || defaultMapDispatchToProps;
@@ -34,9 +35,9 @@ export default function createConnect(React) {
     // Helps track hot reloading.
     const version = nextVersion++;
 
-    function computeStateProps(store) {
+    function computeStateProps(store, props) {
       const state = store.getState();
-      const stateProps = finalMapStateToProps(state);
+      const stateProps = finalMapStateToProps(state, props);
       invariant(
         isPlainObject(stateProps),
         '`mapStateToProps` must return an object. Instead received %s.',
@@ -95,15 +96,15 @@ export default function createConnect(React) {
             `or explicitly pass "store" as a prop to "${this.constructor.displayName}".`
           );
 
-          this.stateProps = computeStateProps(this.store);
+          this.stateProps = computeStateProps(this.store, props);
           this.dispatchProps = computeDispatchProps(this.store);
           this.state = {
             props: this.computeNextState()
           };
         }
 
-        recomputeStateProps() {
-          const nextStateProps = computeStateProps(this.store);
+        recomputeStateProps(props = this.props) {
+          const nextStateProps = computeStateProps(this.store, props);
           if (shallowEqual(nextStateProps, this.stateProps)) {
             return false;
           }
@@ -163,6 +164,9 @@ export default function createConnect(React) {
 
         componentWillReceiveProps(nextProps) {
           if (!shallowEqual(nextProps, this.props)) {
+            if (statePropsDependOnParentProps) {
+              this.stateProps = computeStateProps(this.store, nextProps);
+            }
             this.recomputeState(nextProps);
           }
         }

test/components/connect.spec.js

@@ -375,6 +375,45 @@ describe('React', () => {
       expect(div.props.stateThing).toBe('HELLO azbzcZ');
     });
 
+    it('should pass state and parent props to mapStateToProps', () => {
+      const store = createStore(stringBuilder);
+
+      @connect(
+        (state, props) => ({idString: `[${props.id}] ${state}`}),
+      )
+      class Container extends Component {
+        render() {
+          return <div {...this.props}/>;
+        };
+      }
+
+      class OuterContainer extends Component {
+        constructor() {
+          super();
+          this.state = {id: 0};
+        }
+
+        render() {
+          return (
+            <Provider store={store}>
+              {() => <Container id={this.state.id} />}
+            </Provider>
+          );
+        }
+      }
+
+      const tree = TestUtils.renderIntoDocument(<OuterContainer />);
+      const div = TestUtils.findRenderedDOMComponentWithTag(tree, 'div');
+
+      expect(div.props.idString).toBe('[0] ');
+      store.dispatch({type: 'APPEND', body: 'a'});
+      expect(div.props.idString).toBe('[0] a');
+      tree.setState({id: 1});
+      expect(div.props.idString).toBe('[1] a');
+      store.dispatch({type: 'APPEND', body: 'b'});
+      expect(div.props.idString).toBe('[1] ab');
+    });
+
     it('should merge actionProps into WrappedComponent', () => {
       const store = createStore(() => ({
         foo: 'bar'