undefined is not an object this.props - react-native

Question

I try to use navigation between screen in my RN app. This is my code :
INDEX.ANDROID.JS :
import React, { Component } from 'react';
import {
AppRegistry,
Text,
View ,
Button
} from 'react-native';
import {StackNavigator} from 'react-navigation';
import Login from './app/components/Todo';
const SimpleApp = StackNavigator({
Login: { screen: Todo },
});
export default class aap extends Component {
static navigationOptions = { title: 'Welcome', };
render() {
const { navigate } = this.props.navigation;
return (
<Button onPress ={() => navigate('Todo') } title="go"/>
);
}
}
AppRegistry.registerComponent('aap', () => aap);
here is the code of the second screen TODO.JS
import React, { Component } from 'react';
import {
AppRegistry,
Text,
View ,
Button
} from 'react-native';
export default class Todo extends Component {
render() {
return (
<View>
<Text>
Here is my text
</Text>
</View>
);
}
}
When running my code i get an error : undefined is not an object this.props.naviagtion.
Any help is appreciated

Answer 1

You are not using StackNavigator correctly.
Like #xght said, you should be registering SimpleApp instead of aap. Also, you should be using aap as the initial route to your StackNavigator SimpleApp.
This should look something like this:
import React, { Component } from 'react';
import {
AppRegistry,
Text,
View ,
Button
} from 'react-native';
import {StackNavigator} from 'react-navigation';
import Todo from './app/components/Todo';
class aap extends Component {
static navigationOptions = { title: 'Welcome', };
render() {
const { navigate } = this.props.navigation;
return (
<Button onPress ={() => navigate('Todo') } title="go"/>
);
}
}
const SimpleApp = StackNavigator({
Login: { screen: aap },
Todo: { screen: Todo },
});
AppRegistry.registerComponent('aap', () => SimpleApp);

Answer 2

You registered the wrong component, so the navigator SimpleApp doesn't pass the navigation prop to your component.
Replace
AppRegistry.registerComponent('aap', () => aap); by:
AppRegistry.registerComponent('aap', () => SimpleApp);
And also you forgot to add your aap component in SimpleApp routes. And your import Login from './app/components/Todo';is wrong: Login is the name of the route in SimpleApp, and Todo is the name of the component, so you need to replace it by import Todo...