如何在ReactJS中的组件之前加载数据？

Question

My purpose for the project is to get the data from Google Analytics API and show all the data as a list. I can get the data from API successfully. I am passing the data to another component. I can see that data is the console but when I am trying to load them into the component I am getting nothing. My first component look as below:

class TabsExample extends Component {
      constructor(props) {
       super(props);
       this.handleLoad = this.authorize.bind(this);
       this.handleProfiles = this.handleProfiles.bind(this);
       this.arr = [];
       this.state = {
        info: [],
        details: []
       }
     }

    componentDidMount() {
     window.addEventListener('load', this.handleLoad);
    }

    handleAccounts = (response) => {
     var details = response.result.items;
     console.log(response)
     this.setState({
      info: details
     });
     details.map(x => {
      gapi.client.analytics.management.webproperties.list(
        { 'accountId': x.id })
        .then(this.handleProperties)
        .then(null, function (err) {
          console.log(err);
        })
      })
     }

    handleProperties = (response) => {
      // Handles the response from the webproperties list method.
      if (response.result.items && response.result.items.length) {

      // Get the first Google Analytics account
      var firstAccountId = response.result.items[0].accountId;

      // Get the first property ID
      var firstPropertyId = response.result.items[0].id;

      // Query for Views (Profiles).
      this.queryProfiles(firstAccountId, firstPropertyId);
      //console.log(firstPropertyId)
    } else {
      console.log('No properties found for this user.');
     }
    }

    queryProfiles = (accountId, propertyId) => {
    // Get a list of all Views (Profiles) for the first property
    // of the first Account.
    gapi.client.analytics.management.profiles.list({
      'accountId': accountId,
      'webPropertyId': propertyId
    })
      .then(this.handleProfiles)
      .then(null, (err) => {
        // Log any errors.
        console.log(err);
      })
    }

     handleProfiles(response) {
    // Handles the response from the profiles list method.
    if (response.result.items && response.result.items.length) {
      // Get the first View (Profile) ID.
      var firstProfileId = response.result.items[0].id;

      // Query the Core Reporting API.
      //console.log(firstProfileId);
      //this.queryCoreReportingApi(firstProfileId);
      gapi.client.analytics.data.ga.get({
        'ids': 'ga:' + firstProfileId,
        'start-date': '30daysAgo',
        'end-date': 'today',
        'metrics': 'ga:sessions, ga:bounces, ga:users'
      })
        .then((response) => {
          // this.setState({
          //   details: [this.state.details, response]
          // })
          this.arr.push(response)
        })
    } else {
      console.log('No views (profiles) found for this user.');
    }
    }

    queryCoreReportingApi(profileID) {
     console.log(profileID);
    }

    authorize = (event) => {
    var useImmidiate = event ? false : true;
    var authData = {
      client_id: CLIENT_ID,
      scope: SCOPES,
      immidiate: useImmidiate
    };
    gapi.auth.authorize(authData, (response) => {
      gapi.client.load('analytics', 'v3').then(() => {
        //console.log(response);
        gapi.client.analytics.management.accounts.list()
          .then(this.handleAccounts);
      });
    });
    }

    render() {
    return (
      <Tabs>
        <Tab label="Accounts" >
          <div>
            <NewsList info={this.arr} />
            {this.arr}
          </div>
        </Tab>
        <Tab label="Visual Data" >
          <div>
            <h2 className='tab_headline'>Tab Two</h2>
            <div className="row">
              <div className="col-md">
                <img src="https://upload.wikimedia.org/wikipedia/commons/thumb/2/2e/Pie_chart_EP_election_2004.svg/1280px-Pie_chart_EP_election_2004.svg.png"
                  alt="First"
                  className="img-thumbnail"
                  style={divHeight} />
              </div>
              <div className="col-md">
                <img src="https://confluence.atlassian.com/fisheye/files/298976800/299139805/3/1484820924815/FishEye_Charts_Page02.png"
                  alt="First"
                  className="img-thumbnail"
                  style={divHeight} />
              </div>
            </div>
          </div>
        </Tab>
        <Tab
          label="User Information"
          data-route="/home">
          <div>
            <h2 className='tab_headline'>Tab Three</h2>
          </div>
        </Tab>
       </Tabs>
      )
     }
    }

I am passing all the data to below component:

import React, { Component } from 'react';
     class newsList extends Component {
     items = (props) => {
       if(props){
           return props.info.map((prop)=>{
               return(
                   <div>{prop.result.id}</div>
               )
           })
       }
     }

     render() {
        return(
            <div>
                <ul className="collection">
                    {console.log(this.state.details)}
                </ul>
            </div>
        )
     }
      }

     export default newsList;

When I see the console log I can see the Array [ ] . At the start it is not having any data. After sometime when I click again on Array [ ] I can see that it is having 2 objects. but I cannot use these objects. How can I do this?

Answer 1

Your current implementation does not utilise your React Component 's state .

At the moment, your arr value is simply attached to this , therefore, React cannot see when it changes.

Embedding your arr value within your React component 's state will trigger a render() every time it is changed using this.setState() , thereby making your application responsive to changes in it's value.

See below for an example of implementation.

Init:

constructor(props) {
   super(props)
   this.state: {
     arr: []
   }
 }

Update:

this.setState({
  arr: response
})

Retrieve:

const arr = this.state.arr