React Native Navigation（StackNavigator）：我收到一条错误消息：“ undefined不是对象（正在评估'this.props.navigate'）”

Question

I have just started learning react-native.... Doing a pet project now.... In the app there's a button on clicking it navigates to another screen. I get the following error saying " undefined is not an object (evaluating 'this.props.navigate') " The following are the files

index.js

  import React from "react";
  import Navigator from "./config/routes";
  export default () => <Navigator />;

The code in my config/routes.js

import { StackNavigator } from "react-navigation";

import Home from "../screens/Home";
import List from "../screens/List";

export default StackNavigator({
  Home: {
    screen: Home,
    navigationOptions: {
      header: () => null
    }
  },
  List: {
     screen: List
  }
});

and my component file Home.js which has the button which on click clicking navigates to another screen

 /*all import statements*/
 class Home extends Component {
    handlePressBaseCurrency() {
       console.log("base currency button clicked");
       this.props.navigation.navigate("List"); /* error from this line */
    }
    render() {
            return (
                <UserInput
                    currencyShort={TEMP_BASE_CURRENCY}
                    onPress={this.handlePressBaseCurrency}
                    defaultValue={TEMP_BASE_PRICE}
                    keyboardType="numeric"
                    onChangeText={this.handleTextChange}
                />
            );
        }
 }

Please help!!! Thanks in advance :D

Answer 1

this is not bound correctly in handlePressBaseCurrency . You can:

1. Explicitly bind this in your constructor:

    constructor(props) { super(props); this.handlePressBaseCurrency = this.handlePressBaseCurrency.bind(this); } 

2. From the React Docs on handling events :

   If calling bind annoys you, there are two ways you can get around this. If you are using the experimental public class fields syntax , you can use class fields to correctly bind callbacks:

    handlePressBaseCurrency = () => { console.log("base currency button clicked"); this.props.navigation.navigate("List"); };