how to change params value passed to axios route to change data react native? - react-native

Question

I am building a kind of book app (Holy Quran )... user will go for a list of Surahs, each Surah contains around 5 - 50 pages. I managed navigating user from the list to first page of each Surahs.. and through getting an api request data for first page will be shown and this is the code in the showScreen
const [quran, setQuran] = useState([]);
const page = navigation.getParam('page');
const name = navigation.getParam('name');
let pageNumber = page;
useEffect(() => {
Quran();
}, []);
const Quran = async () => {
const response = await QuranApi.get(`/${pageNumber}/quran-uthmani`);
setQuran(response.data.data.ayahs);
}
so let's imagine that first page is page number 200, I am looking for some way so when user clicks go to page 201 or 199 (next or previous) and refetching the data so show for him requested page
I need some help here please and thanks in advance

Answer 1

Basically you need to add some sort of button or any element in your 'markup section' which will trigger next/previous action. For example:
// The following line makes react listen for changes in page state variable.
// If you use setPage() anywhere, react will auto update all the components
// where page variable is used. You don't need to manually do it
const [page, setPage] = useState(nav.getParam('page'))
// ....
// This function does exactly that
const handleClick = event => {
if(event.target.value === 'next-page') // If next button was pressed
setPage(page + 1) // We increment the page state variable by 1
else if(event.target.value === 'prev-page') // If prev button was pressed
setPage(page - 1) // We decrement the page state variable by 1
// By doing so, react will auto update every element which uses this variable
}
// .....
// We tell react, if [page] state variable changes by user clicking
// next or previous button, fetch data from the api using updated
// page number and using that, we update the [quran] variable using
// 'setQuran()' function
useEffect(async () => {
const response = await QuranApi.get(`/${page}/quran-uthmani`)
setQuran(response.data.data.ayahs)
}, [page] );
//......
// markup section
return(
//....
<Button onClick={handleClick} value="next-page">Next Page {page + 1}</Button>
<Button onClick={handleClick} value="prev-page">Prev Page {page - 1}</Button>
//....
)

Answer 2

Thank you dear #Sayed it finally works but I have to make some modifications with the same idea to be
const [page, setPage] = useState(navigation.getParam('page'))
const handleRightClick = () => {
setPage(parseInt(page) + 1)
};
const handleLeftClick = () => {
setPage(parseInt(page) - 1);
}
useEffect(() => {
return () => {
console.log("cleaned up");
};
}, []);
useEffect(() => {
Quran();
}, [page]);
<Button title = 'Next Page' onPress = {handleRightClick}/>
<Button title = 'Prev-page' onPress ={handleLeftClick} />
So it's working well in that case without an error

Answer 3

Try this small change...
const [page,setPage]=useState(nav.getParam('page'))
useEffect(() => {
Quran();
}, [page]);
by passing an empty array as a second parameter to the useEffect function, you are telling react to only execute the side effect once (at mount time).
However if that array contains a list of state variables to watch for. React will only re-run the side effect if one of the items in this array changes.
The above mentioned change in useEffect would make your useEffect sensitive to any change in the state variable (page) passed to the useEffect array. As you pass new pagenumbers in the url as a parameter, it would result in calling useEffect everytime as the page state variable is set.
Hope this helps!