数据加载时显示加载器图标

Question

I am trying to show loader icon when data loads. But for some reason I am not being able to display this loader icon when I am trying to retrieve data from API.

I have folder structure like this:

• components
  • dashboard
    • Cards.js
    • Dashboard.js

I have following code in my Cards.js

constructor(props) {
    super(props);
    this.state = this.state = {
        posts: [],
        loading: false
    }
}

componentWillMount() {
    this.loadData();
}

render() {
    let data;
    if(this.state.loading) {
        data = <img data-src={ require('../images/loader.gif') } />
    } else {
        let records = this.fetchResult();

        console.log(records);

        return (
            <div className='row'>
                { records }
            </div>
        )
    }
}

// ==================================================================
loadData() {
    const path = `${url}/jira_jobs.php`;
    axios.get(path)
        .then(res  => {
            this.setState({
                posts: res['data'],
                loading: false
            });
        })
        .catch(err => {
            console.error(err);
        });
}

fetchResult() {
    let records = this.state.posts.map((post) => (
        <div key = { post.id }>
            <h3>{ post.title }</h3>
            <p>{ post.body }</p>
        </div>
    ));

    return records;
}

Answer 1

You aren't setting loading to true anywhere. Try setting loading to true at the beginning of the loadData() method:

loadData() {
    this.setState({loading: true});
    const path = `${url}/jira_jobs.php`;
    axios.get(path)
        .then(res  => {
            this.setState({
                posts: res['data'],
                loading: false
            });
        })
        .catch(err => {
            console.error(err);
        });
}

This works due to the asynchronous nature of the promises you are using.

Answer 2

You don't set your loading property to true anywhere. You should set it to true in the beginning of your loadData function like this:

loadData() {
    this.setState({
       loading: true
    });
    const path = `${url}/jira_jobs.php`;
    axios.get(path)
        .then(res  => {
            this.setState({
                posts: res['data'],
                loading: false
            });
        })
        .catch(err => {
            console.error(err);
        });
}

Also in your render method do this:

render() {
    if(this.state.loading) {
        return <img data-src={ require('../images/loader.gif') } />;
    } else {
        let records = this.fetchResult();

        console.log(records);

        return (
            <div className='row'>
                { records }
            </div>
        )
    }
}

Answer 3

You don't set loading to true inside loadData and you aren't returning the loader from render, Also don't forget to set loading to false when error occurs.

loadData() {
  this.setState({ loading: true });
  const path = `${url}/jira_jobs.php`;
  axios.get(path)
    .then(res => {
      this.setState({
        posts: res['data'],
        loading: false
      });
    })
    .catch(err => {
      this.setState({ loading: false });
      console.error(err);
    });
}

With the ternary operator ? you can include your loader in a much nicer syntax then if else

Also the image source should be src and not data-src

render() {
  return (
    <div className='row'>
      {this.state.loading
        ? <img src={require('../images/loader.gif')} />
        : this.fetchResult()
      }
    </div>
  );
}

Answer 4

try to this code

    loadData() {
const {loading,posts}this.state
    this.setState({!loading});
    const path = `${url}/jira_jobs.php`;
    axios.get(path)
        .then(res  => {
            this.setState({
                posts: res['data'],
                !loading
            });
        })
        .catch(err => {
            console.error(err);
        });
}

tell me if it work or not in commit