How to access array in array from react component?

Question

I have this array:

{
  "firstname": "Jessica",
  "lastname": "Wood",
  "favorite": {
        "movie": Flint Town,
        "drink": Sprite
  }
}

I am trying to get drink and i got Objects are not valid as a React child found: object with keys.

How can i fix that?

My react component:

import React, { Component } from 'react';
import axios from 'axios';

class Home extends Component {

  state = {
    info: []
  }

  componentDidMount() {
    axios.get('http://localhost:9000/api')
      .then(res => {
        const info = res.data;
        this.setState({ info });
      })
  }

  render() {
    return (
      <ul>
        <li>{this.state.info.favorite.drink}</li>
      </ul>
    )
  }
}
export default Home;

Is Sprite a string? You would need to convert the values in your "favorite" object to be strings or numbers otherwise you would not be able to render them. — Cat_Enthusiast
– Cat_Enthusiast, Commented May 19, 2019 at 0:20
@ramirozap it is array, when i do this.state.info.firstname it works correctly. — Yevhen Kuzmenko
– Yevhen Kuzmenko, Commented May 19, 2019 at 0:24
@slower. Flint Town and Sprite dont seem to be strings. You need to turn them into strings in order for this to work correctly. — Cat_Enthusiast
– Cat_Enthusiast, Commented May 19, 2019 at 0:28

Cat_Enthusiast · Accepted Answer · 2019-05-19 01:31:40Z

2

You need to parse the values inside the "favorite" object so that they can be rendered as strings.

It also looks like you're trying to access a prop in this.state.info before it exists. Which is why it gives you the undefined error. The render method runs before you assigned anything to info, which you did in componentDidMount().

To workaround this, we can have a loading-state value to determine what to show. The loading-state will toggle after your componentDidMount() logic has completed, ensuring your state has populated.

Here's the sandbox: https://codesandbox.io/s/bold-germain-k3f23

class Home extends Component {
  state = {
    info: {},
    loading: true
  };

  componentDidMount() {
    axios.get("http://localhost:9000//").then(res => {
      const info = res.data;
      const parsedInfo = {
        ...info,
        favorite: Object.entries(info.favorite).reduce((obj, [k, v]) => {
          obj[k] = "" + v;
          return obj;
        }, {})
      };

      this.setState({ info: parsedInfo, loading: false });
    });
  }

  render() {
    const { loading, info } = this.state;
    if (loading) {
      return <div>Loading</div>;
    } else {
      return (
        <div>
          <div>{info.favorite.movie}</div>
          <div>{info.favorite.drink}</div>
        </div>
      );
    }
  }
}

edited May 19, 2019 at 1:31

answered May 19, 2019 at 0:35

Cat_Enthusiast

15.7k5 gold badges26 silver badges47 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Yevhen Kuzmenko Over a year ago

Hello Christopher, with this code i got an error: Line 7: 'myObj' is not defined.

Cat_Enthusiast Over a year ago

Oh that's my bad, I meant to say "info" in place of "myObj". See edit above. Thank you @slower

Cat_Enthusiast Over a year ago

@slower any luck on implementing the above? Let me know if that gives you any errors, I know I had a typo.

Yevhen Kuzmenko Over a year ago

if i do console.log(this.state.parsedInfo.favorite.drink) in componentDidMount() it works but if i move it to render function it gives me: Cannot read property 'parsedInfo' of null

Yevhen Kuzmenko Over a year ago

It works. Thanks for help. You just killed that one but its very sad that things like this in javascript is so difficult. I write mostly in php now and it looks like hell when you are beginner like me. :D Anyway thanks for help, you did a great job.

|

Collectives™ on Stack Overflow

How to access array in array from react component?

1 Answer 1

7 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Related