如何在 React Native 中访问 parent 组件中的 child 组件值（在 ListView 中）

Question

我的应用有一个呈现项目列表的列表视图。

我的 child 组件的每次点击都会触发状态值的变化

{ selected: !this.state.selected }

在上图中，我选择了 2 个 child 项目，如何在我的 parent 组件中访问它们的值？

例如，

Big Data: true
IoT: true

这是我的 parent 片段，Hosted on Github too

import InterestItem from './InterestItem';

class AddInterest extends Component {

  componentWillMount() {
    this.createDataSource(this.props);
  }

  componentWillReceiveProps(nextProps) {
    this.createDataSource(nextProps);
  }

  createDataSource({ items }) {
    const ds = new ListView.DataSource({
      rowHasChanged: (r1, r2) => r1 !== r2
    });
    this.dataSource = ds.cloneWithRows(items);
  }

  //return arrays of event from events
  renderRow(item) {
    return <InterestItem item={item} icon={computer} />;
  }

  render() {
    const { centerEverything, skeleton, container, textContainer, contentContainer, listViewContainer,
      titleContainer, descContainer, title, desc, submitContainer, submitTitle } = styles;
    return (
      <View style={[container]}>
        <View style={[centerEverything, textContainer]}>
          <View style={titleContainer}>
            <Text style={[title]}>What kind of events are you interest in?</Text>
          </View>
          <View style={descContainer}>
            <Text style={[desc]}>You'll see more events from the categories you choose.</Text>
          </View>
        </View>

        <View style={[contentContainer]}>
          <ListView
            enableEmptySections
            contentContainerStyle={listViewContainer}
            dataSource={this.dataSource}
            renderRow={this.renderRow}
          />
        </View>

        <View style={[centerEverything, {paddingBottom: 10}]}>
          <View style={[centerEverything, submitContainer]}>
            <Text style={submitTitle}>Submit</Text>
          </View>
        </View>

      </View>
    )
  }
}

这是我的child组件，Hosted on GitHub too

class InterestItem extends Component {

  state = {
    selected: false
  }

  render() {
    const { skeleton, centerEverything, container, textStyle } = styles;
    return(
      <TouchableWithoutFeedback onPress={() => this.setState({ selected: !this.state.selected })}>
        <View style={[centerEverything, container, { backgroundColor: this.state.selected ? '#635eb4' : '#e7e7e7'}]}>
          {this.props.icon}
          <Text style={textStyle}>{this.props.item[0]}</Text>
        </View>
      </TouchableWithoutFeedback>
    )
  }
}

根据@freesoul 的要求，这里是 child 个实例（考虑到我有 8 个 children）

Answer 1

跟进@free-soul，我将对您的代码进行以下修改：

constructor(){
    this.state = {
    //...
        rowStates: {} // Holds the state for each row, identified by the uid property (I'm assuming it is unique, otherwise use some other value)
    }
    this.renderRow = this.renderRow.bind(this);
    this.rowUpdated = this.rowUpdated.bind(this);
}
renderRow(item) {
   // Adds a callback so that we know when an element has been pressed
    return <InterestItem item={item} icon={computer} onPress={() => this.rowUpdated(item)}/>;
}

rowUpdated(item){
     let rowStates = {...this.state.rowStates}; // Make a copy of the object
     rowStates[item.uid] = !rowStates[item.uid];  // If the item is not in the object, !undefined will be evaluated, which results in true, so the operation is safe
     this.setState({rowStates});
}

那么，您的子组件应该如下所示：

class InterestItem extends Component {

  state = {
    selected: false
  }

  render() {
    const { skeleton, centerEverything, container, textStyle } = styles;
    return(
      <TouchableWithoutFeedback onPress={() => {this.setState({ selected: !this.state.selected }); if(this.props.onPress) this.props.onPress(this.props.item)}}>
        <View style={[centerEverything, container, { backgroundColor: this.state.selected ? '#635eb4' : '#e7e7e7'}]}>
          {this.props.icon}
          <Text style={textStyle}>{this.props.item[0]}</Text>
        </View>
      </TouchableWithoutFeedback>
    )
  }
}

希望对您有所帮助

如何在 React Native 中访问 parent 组件中的 child 组件值（在 ListView 中）

How to access child components value (in a ListView) in parent component in React Native

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