Passing AJAX Results As Props to Child Component

Question

I'm trying to create a blog in React. In my main ReactBlog Component, I'm doing an AJAX call to a node server to return an array of posts. I want to pass this post data to different components as props.

In particular, I have a component called PostViewer that will show post information. I want it to by default show the post passed in from its parent via props, and otherwise show data that is set via a state call.

Currently, the relevant parts of my code looks like this.

var ReactBlog = React.createClass({
  getInitialState: function() {
    return {
      posts: []
    };
  },
  componentDidMount: function() {
    $.get(this.props.url, function(data) {
      if (this.isMounted()) {
        this.setState({
          posts: data
        });
      }
    }.bind(this));
  },
  render: function() {
    var latestPost = this.state.posts[0];
    return (
      <div className="layout">
        <div className="layout layout-sidebar">
          <PostList posts={this.state.posts}/>
        </div>
        <div className="layout layout-content">
          <PostViewer post={latestPost}/>
        </div>
      </div>
    )
  }
});

and the child component:

var PostViewer = React.createClass({
  getInitialState: function() {
    return {
      post: this.props.post
    }
  },
  render: function() {
    /* handle check for initial load which doesn't include prop data yet */
    if (this.state.post) {
      return (
        <div>
          {this.state.post.title}
        </div>
      )
    }
    return (
      <div/>
    )
  }
});

The above works if I swap out the if statement and content in my child's render to this.props.* However, this would mean that I couldn't change the content later via state, correct?

TLDR: I want to set a default post to be viewed via props in a child component (results of an AJAX call), and I want to be able to change what post is being viewed by adding onClick events (of another component) that will update the state.

Is this the correct way to go about it?

Current hierarchy of my app's components are:

React Blog
 - Post List
  - Post Snippet (click will callback on React Blog and update Post Viewer)
 - Post Viewer (default post passed in via props)

Thanks!

EDIT:

So what I ended up doing was attaching the props in ReactBlog using a value based on this.state. This ensured that it updates when I change state and renders correctly in child components. However, to do this I had to chain onClick callbacks up through all the various child components. Is this correct? It seems like it could get VERY messy. Here's my full example code:

var ReactBlog = React.createClass({
  getInitialState: function() {
    return {
      posts: [],
    };
  },
  componentDidMount: function() {
    $.get(this.props.url, function(data) {
      if (this.isMounted()) {
        this.setState({
          posts: data,
          post: data[0]
        });
      }
    }.bind(this));
  },
  focusPost: function(slug) {
    $.get('/api/posts/' + slug, function(data) {
      this.setState({
        post: data
      })
    }.bind(this));
  },
  render: function() {
    return (
      <div className="layout">
        <div className="layout layout-sidebar">
          <PostList handleTitleClick={this.focusPost} posts={this.state.posts}/>
        </div>
        <div className="layout layout-content">
          <PostViewer post={this.state.post}/>
        </div>
      </div>
    )
  }
});

var PostList = React.createClass({
  handleTitleClick: function(slug) {
    this.props.handleTitleClick(slug);
  },
  render: function() {
    var posts = this.props.posts;

    var postSnippets = posts.map(function(post, i) {
      return <PostSnippet data={post} key={i} handleTitleClick={this.handleTitleClick}/>;
    }, this);

    return (
      <div className="posts-list">
        <ul>
          {postSnippets}
        </ul>
      </div>
    )
  }
});

var PostSnippet = React.createClass({
  handleTitleClick: function(slug) {
    this.props.handleTitleClick(slug);
  },
  render: function() {
    var post = this.props.data;
    return (
      <li>
        <h1 onClick={this.handleTitleClick.bind(this, post.slug)}>{post.title}</h1>
      </li>
    )
  }
});

var PostViewer = React.createClass({
  getInitialState: function() {
    return {
      post: this.props.post
    }
  },
  render: function() {
    /* handle check for initial load which doesn't include prop data yet */
    if (this.props.post) {
      return (
        <div>
          {this.props.post.title}
        </div>
      )
    }
    return (
      <div/>
    )
  }
});

Still hoping to get some feedback / hope this helps!

You are doing it all right after the edition. Using a state in a parent component to provide with props to the children is the way to go. Your problem was that "getInitialState" only executes once for every component (unless it is unmounted) so when you changed the parent state, even when the child props would change too, its state wouldn't. — GonArrivi

Mike S. Mike S. · Accepted Answer · 2016-08-06T04:10:56

This is an old question, but I believe still relevant, so I'm going to throw in my 2 cents.

Ideally, you want to separate out any ajax calls into an actions file instead of doing it right inside a component. Without going into using something like Redux to help you manage your state (which, at this point in time, I would recommend redux + react-redux), you could use something called "container components" to do all of the heavy state lifting for you and then use props in the component that's doing the main layout. Here's an example:

// childComponent.js
import React from 'react';
import axios from 'axios'; // ajax stuff similar to jquery but with promises

const ChildComponent = React.createClass({
  render: function() {
    <ul className="posts">
      {this.props.posts.map(function(post){
        return (
          <li>
            <h3>{post.title}</h3>
            <p>{post.content}</p>
          </li>
        )
      })}
    </ul>
  }
})

const ChildComponentContainer = React.createClass({
  getInitialState: function() {
    return {
      posts: []
    }
  },
  componentWillMount: function() {
    axios.get(this.props.url, function(resp) {
      this.setState({
        posts: resp.data
      });
    }.bind(this));
  },
  render: function() {
    return (
      <ChildComponent posts={this.state.posts} />
    )
  }
})

export default ChildComponentContainer;

Passing AJAX Results As Props to Child Component

3 Answers