context undefined while use ES6 constructor

[imshenyz]

All issue in the code:

import React, { Component, PropTypes } from 'react';
import ReactDOM from 'react-dom';
import { Router, Route, Link, browserHistory } from 'react-router'

export default class App extends Component {
    // If use constructor below this.context is undefined, 
    // otherwise comment the constructor statement this.context not null
    // Uncaught TypeError: Cannot read property 'router' of undefined
    router = this.context.router;
    constructor (props) {
        super(props);
        console.log(this);
    }
    render () {
        return <span>ReactDemo</span>
    }
    static contextTypes = {
        router: PropTypes.object.isRequired
    };
}

ReactDOM.render((
    <Router history={browserHistory}>
        <Route path="/" component={App}/>
    </Router>
), document.getElementById('root'));

The react versioin is 15.0.1,i remember a previous version without this problem.
Is this a bug or the usage of my problem?
Here is my demo git:
https://github.com/shenyzore/react-demo.git
Thanks!

[kalaxiya]

you should pass the second param:

constructor(props, context) {
// context can be accessed now
}

[imshenyz]

@Linzerui it works, thanks a lot!

[depoulo]

Is this documented anywhere? I just went looking under https://facebook.github.io/react/docs/ but eventually got here via Google because I couldn't find it there...

[imshenyz]

@depoulo I think there is no document for this, but you can inspired by the usage of context-in-stateless-functional-components

[depoulo]

Which is far from ideal, but thx anyway!

[JanMouwes]

Update for 16.x: passing context to constructor is not documented in 'current' documentation, I did find it in the legacy-documentation though. This leads me to believe it is deprecated.

According to the new documentation in the section that links to the legacy-docs: "The old API will be supported in all 16.x releases, but applications using it should migrate to the new version. The legacy API will be removed in a future major React version." (Found here)

[MilanVilov]

you should pass the second param:

constructor(props, context) {
// context can be accessed now
}

Thank you!