StackNavigator through Component gives undefined error

问题

I was trying to use StackNavigator for navigation and it works when I use it to go from one screen to the other as explained here. But when I try to have a subcomponent to navigate through itself, the navigation doesn't seem to work and I couldn't find any solution to it.

As given in the code below, I'm trying to use the Test Component in which there is a button that can be clicked to move from HomeScreen to ChatScreen.

I'm pretty sure the solution is something basic, but I really can't find it anywhere.

Here's my code:

import React from 'react';
import {
  AppRegistry,
  Text,
  View,
  Button
} from 'react-native';
import { StackNavigator } from 'react-navigation';

class HomeScreen extends React.Component {
  static navigationOptions = {
    title: 'Welcome',
  };
  render() {
    const { navigate } = this.props.navigation;
    let userName = 'Ketan';
    return (
      <View>
        <Text>Hello, Chat App!</Text>
        <Button
          onPress={() => navigate('Chat', { user: userName })}
          title={"Chat with " + userName}
        />
        <Test />
      </View>
    );
  }
}

class ChatScreen extends React.Component {
  static navigationOptions = ({ navigation }) => ({
    title: `Chat with ${navigation.state.params.user}`,
  });
  render() {
    const { params } = this.props.navigation.state;
    return (
      <View>
        <Text>Chat with {params.user}</Text>
      </View>
    );
  }
}

class Test extends React.Component {
  render() {
    const { navigate } = this.props.navigation;
    return (
      <View>
        <Button
          onPress={() => navigate('Chat', { user: 'TestBot' })}
          title={'This is a test'}
        />
      </View>
    )
  }
}

const NavApp = StackNavigator({
  Home: { screen: HomeScreen },
  Chat: { screen: ChatScreen },
});

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

Here's the error I'm getting:

Here's the demo to test: https://snack.expo.io/HyaT8qYob

I hope my question is clear enough of what I mean.

回答1:

Since your Test component does not belong to navigation stack it doesn't have the navigation prop. You can do couple of things.

Simple one is to pass the navigation to the child component like the example below.

return (
  <View>
        <Text>Hello, Chat App!</Text>
        <Button
          onPress={() => navigate('Chat', { user: userName })}
          title={"Chat with " + userName}
        />
        <Test navigation={this.props.navigation} />
      </View>
);

The second option is, you can use withNavigation from react-navigation. You can find more details about it here

import { Button } 'react-native';
import { withNavigation } from 'react-navigation';

const MyComponent = ({ to, navigation }) => (
    <Button title={`navigate to ${to}`} onPress={() => navigation.navigate(to)} />
);

const MyComponentWithNavigation = withNavigation(MyComponent)

withNavigation

withNavigation is a higher order component which passes the navigation prop into a wrapped component. It's useful when you cannot pass the navigation prop into the component directly, or don't want to pass it in case of a deeply nested child.

来源：https://stackoverflow.com/questions/46457706/stacknavigator-through-component-gives-undefined-error