firebase :: Cannot read property 'props' of null

Question

Hello i am trying to use react-router with firebase. but it gives me this error.

Cannot read property \'props\' of null

this is exac

Answer 1

In your callback, the this pointer no longer points to your React component. There are many ways to deal with this:

Capture this into another variable

var component = this;
query.on("child_added", function hello (snapshot) {
    ...
    component.props.router.push('Index');
});

Explicitly bind this

query.on("child_added", function hello (snapshot) {
    ...
    this.props.router.push('Index');
}).bind(this);

Use fat arrows, which implicitly keeps this

query.on("child_added", snapshot => {
    ...
    this.props.router.push('Index');
});

Note that this is a very common problem that developers have in JavaScript and I highly recommend you learn more about the way this behaves with callbacks:

• Polymer this.push not working
• how to call a function inside a self-executing anonymous function?
• Use of the JavaScript 'bind' method
• Firebase Login with React Components