react-router-v4-onEnter.jsx

import { matchPath } from 'react-router';

class MainRouter extends Component {
  static displayName = 'MainRouter';
  static propTypes = {
    store: React.PropTypes.object,
    component: React.PropTypes.oneOfType([
      React.PropTypes.element,
      React.PropTypes.func,
    ])
  };

  render() {
    const { component, store } = this.props;

    const requireAuth = (state) => !isSignedIn(state) ? '/login': null;
    const requireNotAuth = (state) => isSignedIn(state) ? '/' : null;

    const createSelectLocationState = () => {
      let prevRoutingState, prevRoutingStateJS;
      return (state) => {
        const routingState = state.get('routing');
        if (typeof prevRoutingState === 'undefined' || !prevRoutingState.equals(routingState)) {
          prevRoutingState = routingState;
          prevRoutingStateJS = routingState.toJS();
        }
        return prevRoutingStateJS;
      };
    };
    
    return (
      <Router history={history}>
        <App>
          <CustomSwitch store={store}>
            <Route path="/" exact={true} component={Index} />
            <Route path="/login" component={Login} onEnter={requireNotAuth} />
            <Route path="/register" component={Register} onEnter={requireNotAuth} />
            <Route component={ErrorNotFound} />
          </CustomSwitch>
        </App>
      </Router>
    );
  }
}

class CustomSwitch extends Switch {
  render() {
    const { route } = this.context.router;
    const { children, store } = this.props;
    const location = this.props.location || route.location;

    let match, child;
    let foundRedirect = false;
    React.Children.forEach(children, element => {
      if (!React.isValidElement(element)) return;
      if (foundRedirect) return;

      const { path: pathProp, exact, strict, from, onEnter } = element.props;
      const path = pathProp || from;

      if (match == null) {
        child = element;
        match = path ? matchPath(location.pathname, { path, exact, strict }) : route.match;

        if (match && onEnter) {
          const returnedValue = onEnter(store.getState());
          if (returnedValue) {
            browserHistory.push(returnedValue);
            foundRedirect = true;
          }
        }
      }
    });

    return match ? React.cloneElement(child, { location, computedMatch: match }) : null;
  }
}