I want to update the previous screen's useState value and refresh the screen on click of goBack(), I know there is a useIsFocused() to do that but using this screen it is refreshing every time i goBack to the screen, suppose there is a ScreenA and ScreenB, So when user is performing any action in ScreeB then I am dispatching a value using redux and on goBack I am updating the useState value and refreshing the screenA, But it not working, I don't know what's the problem, Please help.
ScreenB
const leaveGroup = () => {
hideMenu();
callLikeMindsApi(`URL`, httpMethods.HTTP_PUT)
.then(response => {
if (response && response.data && response.data.success) {
hideMenu();
dispatch(updateHomeScreen(true));
props.navigation.goBack();
}
})
.catch(error => {
Alert.alert('FAILED', error.response.data.error_message);
});
};
And In ScreenA
const {updateValue} = useSelector(state => state.homeReducer);
useEffect(() => {
console.log('updateValue-1234', updateValue);
}); // it is printing true in console if (updateValue) { setOffset(1); setTotalPages(1); setMyChatRooms([]); getUserData(); } }, [isFocused]);
But
setOffset(1);
setTotalPages(1);
setMyChatRooms([]);
values are not updating, if I remove the if(updateValue){} and writing like this
useEffect(() => {
setOffset(1);
setTotalPages(1);
setMyChatRooms([]);
getUserData();
}, [isFocused]);
then code is working as expected, But it is refreshing every time I come back to the screenA and I want to refresh conditionally.
instead of props.navigation.goBack(); do
props.navigation.navigate('ScreenA',{details});
with the prop that you want pass
in screen A get that value in state from route params
ScreenA = (props) => {
const [navigateState] = useState(props.route.params.details|}{});
---while navigating to Screen B---
props.navigation.navigate('ScreenB',{details: navigateState});
...
I can't get full your code and understand the full logic but if you have already implemented redux you should use it like this:
const {updateValue} = useSelector(state => state.homeReducer);
useEffect(()=>{
if (updateValue) {
// update your screen juse by setting some states on the current component.
} else {
// don't update
}
}, [updateValue])
if you dispatch true value for updateValue whereever in your app then screen-A would be updated regardless it's getting focus or not. if you want to update screen-A only when it's on focus you should add focus condition in useEffect.
Related
I got 3 pages
homepage, productList and productDetails
When going from homepage to productList I pass a route param,
navigation.navigate('productList', { showCategory: 'productListA'} )
InitialProcess when component mounted
Inside the productList page when the component is mounted. I am declaring use state like this.
const {showCateory} = route.params;
const [activeTab, setActiveTab] = useState(showCateory);
and calling api using that activeTab
useEffect(() => {
const unsubscribe = navigation.addListener('focus', () => {
async function fetchData() {
try {
await dispatch(
fetchProductList(
activeTab,
),
);
} catch (err) {
console.log(err);
}
}
fetchData();
});
return unsubscribe;
}, []);
User Interaction
But I also add the button in the productList so that user can change the current active tab
<TouchableOpacity onPress={() => changeTab()}></TouchableOpacity>
const changeTab = async () => {
await setActiveTab('productListB'),
await dispatch(fetchProductList(activeTab)
}
Take note that right now active tab and data coming from api is different from when the component is start mounted.
Navigation Change again
When use goes from productList to productDetails. All thing is fine.
But inside the product details I am going back to productList with this.
navigation.goBack().
When I am back in productList page The activeTab is change back to productListA and the data is change back to when component is mounted
Can I pass or change the route params when calling navigation.goBack()?
add activeTab in useEffect depedineces.
as docs say
The array of dependencies is not passed as arguments to the effect function. Conceptually, though, that’s what they represent: every value referenced inside the effect function should also appear in the dependencies array. In the future, a sufficiently advanced compiler could create this array automatically.
useEffect(() => {
const unsubscribe = navigation.addListener('focus', () => {
async function fetchData() {
try {
await dispatch(
fetchProductList(
//this value will always updated when activeTab change
activeTab,
),
);
} catch (err) {
console.log(err);
}
}
fetchData();
});
return unsubscribe;
}, [activeTab]); //<<<<< here
also you need to know setState() does not always immediately update the component. see here
so change this
const changeTab = async () => {
//await setActiveTab('productListB'),
//await dispatch(fetchProductList(activeTab)
setActiveTab('productListB')
dispatch(fetchProductList('productListB'))
}
This might be happening because route.params is still set to { showCategory: 'productListA'} when you are coming back to the screen.
If this is the case, you can fix it by Changing params object in changeTab() like
navigation.setParams({
showCategory: 'productListB',
});
I hope this will fix your problem.
This happens because the callback function inside the focus listener uses the initial value of the state when the function was defined (at initial page render) . Throughout the lifespan of listener the callback function uses this stale state value.You can read more about this behaviour in this answer
Although the answer by Ahmed Gaber works in this case as the listener is cleared and redefined after each state change.Another common work-around is to use an useRef instead of useEffect.A ref is basically a recipe that provides a mutable object that can be passed by reference.
In your case you can initialise activeTab with navigation param value using useRef hook as :
const activeTab = useRef(showCateory);
and the focus listener callback function should be changed to use the Reference current value as
useEffect(() => {
const unsubscribe = navigation.addListener('focus', () => {
async function fetchData() {
try {
await dispatch(
fetchProductList(
activeTab.current, //<<<<<<---------here
),
);
} catch (err) {
console.log(err);
}
}
fetchData();
});
return unsubscribe;
}, []);
and the changeTab function can directly update reference current value
const changeTab = async () => {
setActiveTab.current = 'productListB';
dispatch(fetchProductList('productListB'))
}
I have 2 page, Page A (current page) and page B (next page). I am using react-native-router-flux as navigation. When go back to page A from page B (Actions.pop()) i want to refetch usequery so i put code like this in page A or component A
const { loading, data, refetch: refetchData } = useQuery(QUERY_GET_STATUS, {
fetchPolicy: 'network-only',
});
useEffect(() => {
if(refresh){
refetchData();
}
}, [refresh])
variable refresh is redux state has value true and false. Before go back to page A refresh state will be update first into true. but i found the issue that refetch query not working. Do you have any solution to resolve it ?
If you wanna call function every time when screen on front then you this hook
import { useFocusEffect } from '#react-navigation/native';
import React{useCallback} from 'react'
useFocusEffect(
useCallback(() => {
//function
}, [])
);
I had a similar problem with a different package. I'm not totally sure if this might work for you but I think with react-native-router-flux, you have access to currentScene. So you could add an effect that is called whenever the route changes
const currentScene = Actions.currentScene;
useEffect(() => {
if(refresh && currentScene === "whatever-scene-you-are-on"){
refetchData();
}
}, [refresh, currentScene])
I am having 2 screens in a react native app, both the screens are functional components.
A button on screen 1 leads to screen 2, I select a few checkboxes on screen 2 and click on a button to navigate to screen 1 with adding navigation params.
coming back on screen 1 runs didFocus listener, but param values are undefined, when I hit ctrl+s on in code editor, useEffect runs and values become accessible.
After this, going back to screen 1 from screen 2 runs didfocus listener (as expected) but the param values do not update.
below is useEffect code in screen 1.
useEffect(() => {
navigation.getParam('from') == 'TagFiltersScreen' ? getAllQuestions('mostInsightful', navigation.getParam('tagsFilter')) : getAllQuestions();
const listener = navigation.addListener('didFocus', () => {
navigation.getParam('from') == 'TagFiltersScreen' ? getAllQuestions('mostInsightful', navigation.getParam('tagsFilter')) : getAllQuestions();
});
return () => {
listener.remove();
}
}, []);
I faced the same issue, and here is how I am doing it.
useEffect(() => {
const isFocused = props.navigation.isFocused();
if (isFocused) {
const { params } = props.navigation.state;
navigationFocus(params);
}
const navigationFocusListener = props.navigation.addListener('willFocus', (payload) => {
const params = payload.state.params;
navigationFocus(params);
});
return () => {
navigationFocusListener.remove();
};
}, []);
const navigationFocus = (params) => {
if (params) {
}
}
I'll be curios to know if there is a better way of doing this.
I'm trying to test the OnDidFocus event in my React Native app using react navigation 4 and using the following event listener:
useEffect(() => {
const willFocusSub = props.navigation.addListener(
"onDidFocus",
console.log("testing onDidFocus")
);
return () => {
willFocusSub.remove();
};
});
When I first load the page it works fine but when I move away and then come back to the same screen through the Back button it does not seem to perceive the focus event.
This is my stack
const MovieNavigator = createStackNavigator(
{
MoviesList: HomeMovies,
MovieDetail: MovieDetailScreen,
PopularMovies: PopularMoviesScreen,
CrewMember: CastDetailScreen,
GenreSearch: GenreSearchScreen,
MovieSearch: MovieSearchScreen,
},
I'm in MoviesList and the event is triggered fine, then I move to MovieDetail. If I hit Back and return to MoviesList the event onDidFocus is not triggered at all.
I think you could try "willFocus" instead.
Like this:
const willFocusSub = props.navigation.addListener(
"willFocus",
()=>{console.log("testing willFocus")}
);
Try modyfying your useEffect call to this!
useEffect(() => {
const willFocusSub = props.navigation.addListener(
"onDidFocus",
console.log("testing onDidFocus")
);
return () => {
willFocusSub.remove();
};
},[]);
I found another way to detect the focus and blur event and seems the only way to track an event when using the Back button.
Instead of subscribing to events, I'm check the focus status of the screen using the useIsFocused() hooks available from react-navigation-hooks library.
import { useIsFocused } from "react-navigation-hooks";
...
const [showGallery, setShowGallery] = useState(true);
...
useEffect(() => {
if (isFocused) {
setShowGallery(true);
} else {
setShowGallery(false);
}
console.log("isFocused: " + isFocused);
}, [isFocused]);
Basically I'm checking the status of the screen using isFocused hook every time it changes (when it leaves and returns only same as didFocus and didBlur) and setting the state setShowGallery accordingly to run the carousel when focused and stop it when blurred.
Hope it helps others!
As the docs https://reactnavigation.org/docs/en/next/use-focus-effect.html,
"Sometimes we want to run side-effects when a screen is focused. A side effect may involve things like adding an event listener, fetching data, updating document title, etc."
I'm trying to use useFocusEffect to fetch data everytime that the user go to that page.
on my component I have a function which dispatch an action with redux to fetch the data:
const fetchData = ()=>{
dispatch(companyJobsFetch(userDetails.companyId));
};
Actually I'm using useEffect hook to call fetchData(), but I'd like to fetch data everytime that the user go to that page and not only when rendered the first time.
It's not clear from the documentation how to use useFocusEffect and I'm not having success on how to do it.
Any help?
The docs show you how to do it. You need to replace API.subscribe with your own thing:
useFocusEffect(
React.useCallback(() => {
dispatch(companyJobsFetch(userDetails.companyId));
}, [dispatch, companyJobsFetch, userDetails.companyId])
);
For version react navigation 4.x, you can use addEvent listener
useEffect(() => {
if (navigation.isFocused()) {
resetReviews(); // replace with your function
}
}, [navigation.isFocused()]);
OR
useEffect(() => {
const focusListener = navigation.addListener('didFocus', () => {
// The screen is focused
// Call any action
_getBusiness({id: business?.id}); // replace with your function
});
return () => {
// clean up event listener
focusListener.remove();
};
}, []);
For later version 5.x, you can use hooks to achieve this
import { useIsFocused } from '#react-navigation/native';
// ...
function Profile() {
const isFocused = useIsFocused();
return <Text>{isFocused ? 'focused' : 'unfocused'}</Text>;
}