Why do I need componentWillReceiveProps in this situation?
<p>I have the following component code : </p>

<pre><code>var Answer = React.createClass({

  getInitialState: function(){
        return { comments: []}
  },

  componentWillMount: function(){
        $.ajax({
            context: this,
            method: 'GET',
            url: '/answers/' + this.props.answer.id + '/comments',
            success: function(data){
                this.setState({comments: data});
            }
        });
},

  render: function(){
        return ( 
            &lt;div&gt;
                &lt;Comments comments={this.state.comments} /&gt;
            &lt;/div&gt;
        );
},
</code></pre>

<p>Notice how I fetch new state in <code>componentWillMount</code>, then pass this new state as props to the <code>Comments</code> component. I was expecting that when I <code>setState</code> in <code>componentWillMount</code>, that would take care of refreshing my <code>Comments</code> component and pass the new props, however, it turns out I need this method in my <code>Comments</code> component: </p>

<pre><code>componentWillReceiveProps: function(newProps){
        this.setState({comments: newProps.comments})
},
</code></pre>

<p>Can someone please explain why when my parent component doesn't update the props that are being passed to its child after I set the paren's state? </p>