ReactJs React-Router Navigation

问题:

I am stuck with some issue related to react-router Navigation. In my navigation there are 2 menu login and register, and my index page is login.

On login page after entered the value of emaild and password and submitting login button it get output as sessionValue.My sessionValue is username which return from serverSide and it redirect to TodoApp page. After login it redirected to TodoApp page. I want to display logout menu instead of login in navigation.

My code is as below:

app.jsx

    ReactDOM.render(
  <Router history={browserHistory}>
    <Route path="/" component={Main}>
        <Route path="RegistrationForm" component={RegistrationForm}/>
        <Route path="todoapp/:sessionValue"component={TodoApp}/>
        <IndexRoute component={Login}/>
    </Route>
  </Router>, 
  document.getElementById('app')
);

Navigation component

I tried this by using localstorage but it doesn't work. It works only when I clicked on backward arrow of browser.

 var Nav= React.createClass({
        render:function(){
            var strUserName = localStorage.getItem('sessionValue');
            console.log(strUserName);
        function loginMenu(){
                if(strUserName){

                                return <Link to="/RegistrationForm" activeClassName="active" activeStyle={{fontWeight: 'bold'}}>Logout</Link> 

            }
            else{
                return <IndexLink to="/" activeClassName="active" activeStyle={{fontWeight: 'bold'}}>LogIn</IndexLink> 

            }
        }
            return(
                <div className="top-bar">
                        <div className="top-bar-left">
                            <ul className="menu">
                            <li className="menu-text">
                                React App
                            </li>
                            <li>
                                {loginMenu()}
                            </li>
                            <li>
                                    <Link to="/RegistrationForm" activeClassName="active" activeStyle={{fontWeight: 'bold'}}>Signup</Link>
                            </li>

                            </ul>
                        </div>
                        </div>
                );
        }
        });
 module.exports=Nav;

login page (login.jsx)

if(validForm){
        axios.post('/login', {
        email:this.state.strEmail,
        password:this.state.strPassword
        })
        .then(function (response) {
        //console.log(response.data);
        var sessionValue=response.data;
//After login todoApp page is open and with session value.session value passed through url to todoApp.
        browserHistory.push(`todoapp/${sessionValue}`);
        localStorage.setItem('sessionValue',sessionValue);
 })
        .catch(function (error) {
        console.log(error);
        });
    }
}, 

Questions:

1. how to show/hide login/logout menu.
2. after login show logout menu and when we click on logout menu show login menu

回答1:

You should have some state management strategy behind the scene to implement this behavior. So, you can have the following component structure

App
- Nav
- LoginForm

Without any state management library like redux/mobX you need to have state defined in App component

class App extends Component {
  constructor(props) {
    super(props);
    this.onLoggedInChanged = this.onLoggedInChanged.bind(this);
    this.state = {
      isLoggedIn: false
    }
  }
  onLoggedInChanged(isLoggedIn) {
    this.setState({
      isLoggedIn: isLoggedIn
    });
  }
  render() {
    return (
      <Nav isLoggedIn={this.state.isLoggedIn} />
      <LoginForm onLoggedInChanged={this.onLoggedInChanged}></LoginForm>
    );
  }
}

Then in your Nav component you can use isLoggedIn flag

Nav = () => {
  let loginElement = this.props.isLoggedIn ? 'Logged in user' : 'Not logged in'
  return (<div>{loginElement }</div>)
}

You can find more information about state in react application in their docs here https://facebook.github.io/react-native/docs/state.html

In redux/mobx it will be done in a different way.