CODEWITHSUNDEEP
javascriptreactjs
kronus
kronus

Reputation: 912

React cannot display json - data is assigned a value but never used

I have only been working with React for two days and I am stuck on displaying the results of a fetch for a JSON file. When I do a console.log, the data appears in the console, yet I cannot figure out for the life of me, how to display it back through the render function.

Also, I can not figure out how to pass or set the value of a variable. In this case, I am receiving warning - "data is assigned a value but never used"

I have tried { JSON.stringify(this.Songs, null, 2) }. I have tried to call this.data[0].title to display just the first title in the JSON, but I receive an error that 0 is undefined.

It is like the value of this.data or this.Songs is lost outside of it's original function.

I have tried to use let data, const data, this.data = this.data.bind, etc...

How can I make the values available for render()? And how do I render them to page?

Here's the code and thanks in advance:

import React from 'react';

class Songs extends React.Component {

constructor(){
    super();
    const data = [];
}

componentDidMount() {
    fetch('http://localhost:3000/data.json')
    .then((response) => response.json())
    .then((responseJson) => {
        this.Songs = responseJson;
        this.data = responseJson;
        this.getData(this.Songs);
        this.createColumns();
    })
    .catch((error) => {
        console.error(error);
    });
}

createColumns() {
    this._columns = ['id', 'title', 'original_band', 'description', 'date_posted', 'download_midi_tabs', 'youtube_link', 'download_guitar_m4v' ];
    console.log('inside createColumns: ' + this._columns);
}

getData(data){
    console.log('inside getData');
    console.log(data);
}

render() {
    return (
        <div>
            { JSON.stringify(this.data, null, 2) }
        </div>
    );
 }
}

export default Songs;

Here is a sample of two rows from the JSON:

[ { "id": "1", "title": "2 minutes 2 midnight", "original_band": "Iron Maiden", "description": "", "date_posted": "2012-02-06 17:14:56", "download_midi_tabs": "http://kronusproductions.com/songs_angular/assets/downloads/2_minutes_to_midnight.zip", "youtube_link": "http://youtu.be/VAm3-vyfJwI", "download_guitar_m4v": "http://kronusproductions.com/uploads/serious/2-minutes-to-midnight-vst.mp3", "download_enabled": "1" }, { "id": "2", "title": "909", "original_band": "The Beatles", "description": "Even though this song would be recorded at the end of the Beatles time together, it was one of the first songs that Lennon and McCartney wrote together. I have added horns in the place of the guitar licks that Lennon recorded.", "date_posted": "2012-02-06 17:14:56", "download_midi_tabs": "http://kronusproductions.com/songs_angular/assets/downloads/909.zip", "youtube_link": "https://youtu.be/DxuEYgbUtqE", "download_guitar_m4v": "http://kronusproductions.com/uploads/serious/909-vst.mp3", "download_enabled": "1" }

Upvotes: 0

Views: 2420

Answers (2)

Tholle
Tholle

Reputation: 112787

You have to use setState to set your component state, and this state will reside in state of the component.

Example

class Songs extends React.Component {
  state = {
    data: []
  };

  componentDidMount() {
    fetch("http://localhost:3000/data.json")
      .then(response => response.json())
      .then(responseJson => {
        this.setState({ data: responseJson });
      })
      .catch(error => {
        console.error(error);
      });
  }

  render() {
    return (
      <div>
        {this.state.data.map(obj => {
          return (
            <div>
              <h2>{obj.title}</h2>
              <h3>{obj.original_band}</h3>
              <p>{obj.description}</p>
            </div>
          );
        })}
      </div>
    );
  }
}

Upvotes: 1

Mike Bell
Mike Bell

Reputation: 1386

Your code has a bunch of issues, but I think the biggest one is that you never make any call to setState. Updating of state or props is how React knows to trigger a render.

Upvotes: 0

Related Questions