如何将组件引用传递给onPress回调？

Question

我确实使用onPress"handler"呈现了以下类型的列表.

我已经意识到onPress处理程序是没用的,因为我无法获得按下的种族参考.我得到ref没有定义错误.

var races = Engine.possibleRaces;

function racePressed(ref) {
    console.log("REF: " + ref); // is never called
}

var races = Engine.possibleRaces;
var rowViews = [];
for (var i = 0; i < races.length; i++) {
  rowViews.push(
    <Text
      ref={i}
      onPress={() => racePressed(ref)} // ref is not defined
      style={styles.raceText}>{races[i].text}
    </Text>

  );
}

<View style={{width: Screen.width, flexDirection:'row', flexWrap: 'wrap', alignItems: "center"}}>
       {rowViews}
</View>  

我也尝试将i作为参数传递.它不起作用,因为它在迭代结束后具有值.基本上它有races.length值.

  onPress={() => racePressed(i)} // Same as races.length

编辑:

我确实将问题隔离到以下程序.

'use strict';
import React, {
  AppRegistry,
  Component,
  StyleSheet,
  Text,
  View
} from 'react-native';

let texts = [{text: "Click wrapper text1"}, {text: "Click wrapper text2"}];

class sandbox extends Component {

  rowPressed(ref, i) {
    console.log("rowPressed: " + ref + " " + i)
  }

  render() {

    var rows = [];

    for (var i = 0; i < texts.length; i++) {
      rows.push(
        <Text
          ref={i}
          onPress={() => this.rowPressed.bind(this, i)}
          style={styles.raceText}>{texts[i].text}
        </Text>
      );
    }

    return (
      <View style={styles.container}>

        <View>
          {rows}
        </View>

      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center'
  }
});

AppRegistry.registerComponent('sandbox', () => sandbox);

除非跟随警告,否则不会调用回调并且不会抛出任何错误

[tid:com.facebook.React.JavaScript] Warning: Each child in an array or iterator should have a unique "key" prop. Check the render method of `sandbox`. See https://fb.me/react-warning-keys for more information.

Answer 1

我建议你在构造函数中绑定该函数,如..

constructor(props){
    super(props);
    //your codes ....

    this.rowPressed = this.rowPressed.bind(this);
}

这会this像你期望的那样绑定rowPressed函数的上下文,使你的代码正常工作.

另外,要删除警告消息,您应该key为每个<Text>元素提供唯一属性,<Text key={i} ....>在代码中使用应该可以正常工作.