React Navigation check if previous screen exists

问题:

I am looking desperately for a possibility to check if a previous screen exists in ReactNavigation.

Using this.props.navigation.goBack() returns false if no previous route exists, but I can not use it because if a previous route exists I get redirected.

Is there a possibility to check if I opened the app instead of navigated from another screen to the Home screen?

Thank you. I am not using Redux. It would make such stuff easier but I would like to avoid using it at the moment.

回答1:

What could be a solution (not sure that it's the best one) would be to spend in the param object the previous screen. With that, if the params exists would mean that a previous screen exists.

For example:

const navigateAction = NavigationActions.navigate({
  routeName: 'Profile',

  params: { previous_screen: 'CURRENT_SCREEN' },

  action: NavigationActions.navigate({ routeName: 'NEXT_SCREEN' }),
});

this.props.navigation.dispatch(navigateAction);

And then in the next screen:

const { navigation } = this.props;
if (navigation.state.params && navigation.state.params.previous_screen) {
  // A previous screen exists
} else {
  // No previous screen
}

回答2:

There is an easier way:

if(this.props.navigation.isFirstRouteInParent()) {
    //a previous screen does not exist
} else {
    //a previous screen does exist
}

回答3:

const navigateAction = NavigationActions.navigate({
  routeName: 'NEXT_SCREEN',
  action: NavigationActions.navigate({ routeName: 'NEXT_SCREEN', params: { previous_screen: 'CURRENT_SCREEN' } }),
});
this.props.navigation.dispatch(navigateAction);