Set state in child after it will receive props?

Question

I have two components. One is UserBase on which ajax request is called to get values. When get those values and updated in state of header.

Another component is Header. Its a child component of UserBase. So when the state updated then it pass it to child component.

Now, my problem is I have to update the state of child when it will receive the props from the UserBase component. How can I achieve this functionality.

Here is my code

Header Component

var React = require('react');
var Router = require('react-router');
import Auth from './Auth.js';
import PopupSmall from './PopupSmall.js';

var headerStyle = {
    border:0
}

class Header extends React.Component{

    constructor(){
        super();
        console.log("constructor");
        this.state = {basicInfo : {}};
    }

    // **some function which needs to tigger when this component will receive props**

    popupChange(){
        console.log("============popupChange============");
        console.log(this.state);
        Router.browserHistory.push("/dashboard");
    }

    render(){
        if(this.props.basicInfo){

            return (
                <div>
                {this.props.basicInfo.isAgency==1 ? <PopupSmall popupCallBack={this.popupChange.bind(this)} itemList={this.props.agencies} show='true' title='Agencies'/> : console.log()}
            </div>
            )
        }

    }
}

export default Header;

UserBase Component

import React from 'react';
import Header from './Header.js';
import Auth from './Auth.js';
import Loader from './Loader.js';

var Router = require('react-router');

class Base extends React.Component{
    constructor(){
        super();
        this.state = {basicInfo :[]};
    }

    loadDataFromServer() {
        var tokenId = Auth.getCookies("token");

        if(tokenId!=""){

            var data = {
                token : tokenId
            }

            $.ajax({
              url: 'http://xxx.xxxxxxx.xxx/abc/cde',
              dataType: 'json',
              cache: false,
              type : 'POST',
              data : JSON.stringify(data),
              headers: { 
                    'Accept': 'application/json',
                    'Content-Type': 'application/json' 
                },
              success: function(response) {

                var info = {
                    compName : response.name,
                    firstName : response.fn,
                    isAgency : response.isAgeny
                }

                this.setState({basicInfo:info}, function(){
                    //console.log(this.state.data);
                }.bind(this));

              }.bind(this),
              error: function(xhr, status, err) {
                console.error("", status, err.toString());
              }.bind(this)
            });
        } else {
            Router.browserHistory.push('/login');
        }
    }

    componentDidMount() {
        this.loadDataFromServer();
    }

    render(){
        document.body.className="nav-md";

        return (

            <div className="container body">
              <div className="main_container">
                    <Header basicInfo={this.state.basicInfo} />
              </div>
            </div>

        );
    }
}

export default Base;

Answer 1

If you haven't already, have a read through: https://facebook.github.io/react/docs/component-specs.html

There's one function in particular which may suit what you need here:

componentWillReceiveProps(nextProps, nextState)

Invoked when a component is receiving new props. This method is not called for the initial render.

Use this as an opportunity to react to a prop transition before render() is called by updating the state using this.setState(). The old props can be accessed via this.props. Calling this.setState() within this function will not trigger an additional render.

So your Header component will have a function similar to the following in it (untested):

componentWillReceiveProps(nextProps) {
  if (nextProps.basicInfo !== this.props.basicInfo) {
    this.setState({ basicInfo: nextProps.basicInfo });
  }
}