使用Json Api的ReactNative ListView [英] ReactNative ListView with Json Api

问题描述

我无法在列表视图中显示json数据.我在console.log中获得了json数据，但在listview中却没有得到.isLoading始终为false. 我没有收到任何错误.catch(error => console.warn("error")). 屏幕上的结果是第一个视图"，因为this.state.isLoading为false.

I can't display json data in listview. I get json data in console.log but not in listview isLoading is always on false. I dont get any errors .catch(error => console.warn("error")). Result on screen is first View because this.state.isLoading is false.

这是一个代码:

import React, { Component } from 'react';
import { AppRegistry, StyleSheet, ListView, Text, View,Image,TouchableHighlight } from 'react-native';

var productArray = [];

class ListViewDemo extends Component {
   constructor(props) {
    console.warn("constructor");
    super(props);
    var dataSource = new ListView.DataSource({rowHasChanged:(r1,r2) => r1.guid != r2.guid});
   this.state = {
      dataSource: dataSource.cloneWithRows(productArray),
     isLoading:true
   }
 }

  componentDidMount() {
    console.warn("componentDidMount");
    this.getTheData(function(json){
     productArray = json;
      console.warn(productArray);
     this.setState = ({
       datasource:this.state.dataSource.cloneWithRows(productArray),
       isLoading:false
     })
    }.bind(this));   
     console.warn("component ->  " + this.state.isLoading);
  }

  getTheData(callback) {
    console.warn("callback");
    var url = "https://raw.githubusercontent.com/darkarmyIN/React-Native-DynamicListView/master/appledata.json";
fetch(url)
     .then(response => response.json())
     .then(json => callback(json))
     .catch(error => console.warn("error"));
   }

  renderRow(rowData, sectionID, rowID) {
    console.warn("renderRow");
    return (
        <TouchableHighlight underlayColor='#dddddd' style={{height:44}}>
         <View>
         <Text style={{fontSize: 20, color: '#000000'}} numberOfLines={1}>{rowData.display_string}</Text>
         <Text style={{fontSize: 20, color: '#000000'}} numberOfLines={1}>test</Text>
         <View style={{height: 1, backgroundColor: '#dddddd'}}/>
        </View>
    </TouchableHighlight>
);
}

   render() {
   console.warn("render" + this.state.isLoading);
   var currentView = (this.state.isLoading) ? <View style={{height: 110, backgroundColor: '#dddddd'}} /> : <ListView dataSource={this.state.dataSource} renderRow={this.renderRow.bind(this)} enableEmptySections={true}/>
   return(
     <View>
       {currentView}
     </View>
   );
  }
}

// App registration and rendering
AppRegistry.registerComponent('AwesomeProject', () => ListViewDemo);

推荐答案

我在这里看到了两个错误.

I see a couple of mistakes here.

在您的componentDidMount中，您将datasource设置为dataSource:

In your componentDidMount, you are setting datasource intead of dataSource:

  componentDidMount() {
    console.warn("componentDidMount");
    this.getTheData(function(json){
     productArray = json;
      console.warn(productArray);
     this.setState = ({
       //datasource:this.state.dataSource.cloneWithRows(productArray),
       dataSource:this.state.dataSource.cloneWithRows(productArray),
       isLoading:false
     })
    }.bind(this));   
     console.warn("component ->  " + this.state.isLoading);
  }

这就是为什么您无法渲染的原因，因为dataSource从未填充.这只是一个小小的拼写错误.

That's why you're not being able to render, because dataSource is never populated. It is just a little spelling mistake.

由于没有返回Promise，您可能没有进入第二个getTheData方法:

You are probably not getting into the second then in your getTheData method because you are not returning a Promise:

getTheData(callback) {
  console.warn("callback");
  var url = "https://raw.githubusercontent.com/darkarmyIN/React-Native-DynamicListView/master/appledata.json";
  fetch(url)
     //.then(response => response.json())
     .then(response => return response.json())
     .then(json => callback(json))
     .catch(error => console.warn("error"));
   }

您在setState上犯了一个错误，您是在分配它而不是调用它:

Your are making a mistake with your setState, your are assigning it instead of calling it:

 //this.setState = ({
 //  datasource:this.state.dataSource.cloneWithRows(productArray),
 //  isLoading:false
 //})

 this.setState({
   dataSource:this.state.dataSource.cloneWithRows(productArray),
   isLoading:false
 })

让我知道它是否有效.

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