响应本机，状态项设置错误

Question

    constructor(props) {
            super(props);
            this.state = {
              message: "..",
            };
    }
    render() {
      return (
          <View style={styles.container}>

            <View style={styles.textInput}>

              <TextInput onChangeText={(message) => this.setState({message})} placeholder="Enter your message..." style={styles.text}/>

              <TouchableHighlight style={styles.button} onPress={this.submit}>

                <Text ref="message" onPress={this.submit}>Submit</Text>

              </TouchableHighlight>

            </View>

          </View>
        )
    }

    loadData(){
      AlertIOS.alert(this.state.message);
    }
    componentDidMount(){
      this.loadData()
    }
    submit(){
      AlertIOS.alert(this.state.message);
    }

When loadData is first called, it shows the current value of message: ".."

When my submit function is called, it throws an error: undefined is not an object (evaluating 'this.state.message')

I'm assuming that it is my onChangeText attribute that's setting message to undefined, but I'm not sure why.

Answer 1

The problem is that this isn't bound correctly in submit()

In your constructor, try adding the line:

this.submit = this.submit.bind(this);