update child component when parent component changes

Question

I\'m kind of new to React js. I have two questions. Here I go

Question 1

I wanted to update(re-render) the child component when I update(re-render

Answer 1

this.props.user = res.data.user; 

You can't assign to props. Props are passed from a parent. Set the user in the state and pass the state to your child component like so:

<ABCD {...this.props} user={this.state.user} />

In your child component you will now have access to this.props.user. Also the this.forceUpdate() will not be needed then.