How to make many http requests with react

#discuss #help #fetchapi #react

Hi, please i'm stuck.
is somebody knows how to make many request in a react component or route?

componentDidMount = () => {
    const { match: { params } } = this.props
    fetch(`/w/${params.work}`)
      .then(res => res.json())
      .then(work => this.setState({ work }))

    fetch('/works')
      .then(res => res.json())
      .then(otherWorks => this.setState({ otherWorks }))
}

something like this that works.
I'm a beginner with React so i don't really want things like Redux
i just want a beginner way.The first fetch work but not the second

Top comments (8)

Leighton Darkins • Jun 13 '18 • Edited

I think promise.all() is going to be what you're looking for.

const firstFetch = fetch('some/resource')
const secondFetch = fetch('some/other/resource')

Promise.all([firstFetch, secondFetch])
  .then(values => {
    // do something with values
    // values[0] is the result of firstFetch
    // values[1] is the result of secondFetch
  })
  .catch(error => {
    // handle any errors
  })

Ekim Kael • Jun 13 '18

Okay! i try it

Xing Wang • Jun 14 '18

if you have multiple callback asynchrous update the setState, you should consider this method to make sure they don't overwrite each other or race conditions:

this.setState( prevState => ({ ...prevState, work1: result });

this.setState( prevState => ({ ...prevState, work2: result });

Mikk Pristavka • Jun 13 '18 • Edited

Maybe it's not about the requests, but how you expect to use the responses. The React.Component's setState method is asynchronous, so you can't expect the component's state to have both work and otherWorks every time render() is called.
As Leighton suggested, Promise.all would help you make only one setState call, but it still doesn't cover the case right after mounting the component when neither of the values are present in the state.
Maybe consider adding a loading flag in the state that is set to false when both requests have completed, so render() can show a loading animation while the requests are still waiting for responses.

class MyComp extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      loading: true,
      work: undefined,
      otherWorks: undefined
    };
  }
  componentDidMount = () => {
    const { match: { params } } = this.props
    const fetchWork = fetch(`/w/${params.work}`)
    const fetchOtherWorks = fetch('/works')

    Promise.all([fetchWork, fetchOtherWorks])
      .then(([work, otherWorks]) => {
        this.setState({
          loading: false,
          work,
          otherWorks
        });
      })
      .catch(error => {
        // handle errors
      })
  }

  render() {
    const {loading, work, otherWorks} = this.state;
    if (loading) {
      return <div>Still loading!</div>
    } else {
       return (
         // whatever you want to do with `work` and `otherWorks`
       );
    }
  }  
}