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I want to paginate data. It is working fine but when I search for specific data it always shows in the first page

What I want is to paginate my data but the problem is when I'm searching for specific data if I'm on page 3 the result shows on page 1 always and I can't see anything because I was on page no 3. I want to go to page 1 automatically when I'm searching for something. Also when I press the next button if there is no data at all it still increases the page number.
Here is my code:
import { React, useState, useEffect } from "react";
import UpdateDialogue from "./UpdateDialogue";
function List(props) {
const API_URL = "http://dummy.restapiexample.com/api/v1/employees";
const [EmployeeData, setEmployeeData] = useState([]);
const [pageNumber, setPageNumber] = useState(1);
const [postNumber] = useState(8);
const currentPageNumber = pageNumber * postNumber - postNumber;
const handlePrev = () => {
if (pageNumber === 1) return;
setPageNumber(pageNumber - 1);
};
const handleNext = () => {
setPageNumber(pageNumber + 1);
};
useEffect(() => {
fetch(API_URL)
.then((response) => response.json())
.then((response) => {
setEmployeeData(response.data);
})
.catch((err) => {
console.error(err);
});
}, []);
const filteredData = EmployeeData.filter((el) => {
if (props.input === "") {
return el;
} else {
return el.employee_name.toLowerCase().includes(props.input)
}
});
const paginatedData = filteredData.splice(currentPageNumber, postNumber);
return (
<>
<ul>
{paginatedData.map((user) => (
<UpdateDialogue user={user} key={user.id} />
))}
</ul>
<div>Page {pageNumber} </div>
<div>
<button style={{marginRight:10}} onClick={handlePrev}>prev</button>
<button onClick={handleNext}>next</button>
</div>
</>
);
}
export default List;

Maybe with a useEffect on your input:
useEffect(() => {
if (props.input) {
setPageNumber(1);
}
}, [props.input]);
That way, whenever your input changes, your page number is set to 1.

Component re-renders self after API call whilst using useRef

I'm working on a project and wanted to try and implement an infinitely scrollable page to list users. Filtering and such works fine and all but every time the scrolling component reaches the ref element the component makes an API call to append to the list and then the parent component re-renders self completely.
const UsersList = () => {
const [searchString, setSearchString] = useState('')
const [next, setNext] = useState('')
const { userList, error, nextPage, loading, hasMore } = useFetch(next)
const [usersList, setUsersList] = useState([])
const observer = useRef()
const lastElemRef = useCallback(
(node) => {
if (loading) return
if (observer.current) observer.current.disconnect()
observer.current = new IntersectionObserver((entries) => {
if (entries[0].isIntersecting && hasMore) {
setNext((prev) => (prev = nextPage))
setUsersList((prev) => new Set([...prev, ...userList]))
}
})
if (node) {
observer.current.observe(node)
}
},
[loading, nextPage, hasMore],
)
useEffect(() => {
setUsersList((prev) => new Set([...prev, ...userList]))
console.log(error)
}, [])
return (
<>
{loading ? (
<CSpinner variant="grow"></CSpinner>
) : (
<CContainer
className="w-100 justify-content-center"
style={{ maxWidth: 'inherit', overflowY: 'auto', height: 600 }}
>
<CFormInput
className="mt-2 "
id="userSearchInput"
value={searchString}
onChange={(e) => {
setSearchString(e.target.value)
}}
/>
{loading ? (
<CSpinner variant="grow"></CSpinner>
) : (
<>
{Array.from(usersList)
.filter((f) => f.username.includes(searchString) || searchString === '')
.map((user) => {
if (Array.from(usersList)[usersList.size - 1] === user) {
return (
<UserCard
key={user.id}
user={user}
parentRef={searchString ? null : lastElemRef}
/>
)
} else {
return <UserCard key={user.id} user={user} />
}
})}
</>
)}
</CContainer>
)}
</>
)
}
export default UsersList
This is the component entirely.
Here's my useFetch hook;
export const useFetch = (next) => {
const [userList, setUserList] = useState([])
const [loading, setLoading] = useState(true)
const [error, setError] = useState('')
const [nextPage, setNextPage] = useState(next)
const [hasMore, setHasMore] = useState(true)
useEffect(() => {
setLoading(true)
setError('')
axios
.get(next !== '' ? `${next}` : 'http://localhost:8000/api/getUsers/', {
headers: {
Authorization: 'Bearer ' + localStorage.getItem('access_token'),
},
})
.then((res) => {
setUserList((userList) => new Set([...userList, ...res.data.results]))
setNextPage((prev) => (prev = res.data.next))
if (res.data.next === null) setHasMore(false)
setLoading(false)
})
.catch((err) => {
setError(err)
})
}, [next])
return { userList, error, nextPage, loading, hasMore }
}
export default useFetch
I'm using Limit Offset Pagination provided by Django Rest Framework, next object just points to the next set of objects to fetch parameters include ?limit and ?offset added at the end of base API url. What is it that I'm doing wrong here ? I've tried many different solutions and nothing seems to work.
Solved
Apparently it was just my back-end not cooperating with my front-end so I've changed up the pagination type and now it seems to behave it self.

React - map function?

The idea is to fetch cards that user used in the database and compare with the all cards that are listen on screen. Basically user is not supposed to see cards which he already used.
const loadSaveInvestments = async (
_req: express.Request,
res: express.Response
) => {
const findSaveInvestments = await prisma.investmentSave.findMany({
select: {
investment_id: true,
},
});
if (!findSaveInvestments) throw new HttpException(400, SAVE_INVEST_MISSING);
res.send(findSaveInvestments);
};
So, I'm sending all of the saved investment cards. Now, in the React - I'm fetching the sent data from the service (all cards and saved cards)
const fetchUserSaveInvestments = async () => {
const res = await axios.get(`${baseURL}/investments-save`);
return res;
};
const [cards, setCards] = useState([]);
const [saveCards, setSaveCards] = useState([]);
useEffect(() => {
setLoading(true);
investService.fetchUserSaveInvestments().then((res) => {
setSaveCards(res.data);
});
investService.fetchCards().then((res) => {
setCards(res.data.investments);
setLoading(false);
});
Now - the main part. I want to map card only if it's id is not in the save cards state, so I've tried something like that.. I've marked the point where I got kinda stuck, I mean, am I supposed to create something like double map or what? Idk if I'm going in the right direction.
<div className={classes.CardsContainer}>
<div className={classes.CardsSelector}>
{loading && <p> its loading </p>}
{!loading && (
<>
{cards
.filter(
(card) => card.id !== saveCards.?????.investments_id
)
.map((card) => (
<Card
{...card}
handleClick={() => handleChooseCard(card)}
/>
))}
</>
)}
</div>
Thanks in advance.

I'd try using a Set to keep track of the saved card IDs since it provides O(1) time complexity lookups (fast, better than searching another array for each filter candidate).
const [loading, setLoading] = useState(false)
const [cards, setCards] = useState([])
const [saveCards, setSaveCards] = useState(new Set())
useEffect(async () => {
setLoading(true);
const { data: savedCards } = await investService.fetchUserSaveInvestments()
const savedCardIds = savedCards.map(({ investments_id }) => investments_id)
setSaveCards(new Set(savedCardIds))
const { data: { investments: cards } } = await investService.fetchCards()
setCards(cards)
setLoading(false)
}, [])
You can then use a memo to do the filtering
const myCards = useMemo(() => cards.filter(({ id }) => !saveCards.has(id)), [cards, saveCards])
{myCards.map(card => (
<Card
{...card}
handleClick={() => handleChooseCard(card)}
/>
))}

Simply declare the following state:
const [investmentsIds, setInvestmentIds] = useState([]);
Add few more lines of code here:
investService.fetchUserSaveInvestments().then((res) => {
setSaveCards(res.data);
let savedCardIds = [];
/* push investment_id in an array */
res.data.forEach((value)=>{
savedCardIds.push(value.investments_id);
})
setInvestmentIds(savedCardIds);
});
Your JSX:
<div className={classes.CardsContainer}>
<div className={classes.CardsSelector}>
{loading && <p> its loading </p>}
{!loading && (
{cards.map((card) => (
{investmentsIds.includes(card.id) &&
<Card {...card}
handleClick={() => handleChooseCard(card)}/>
}
))}
)}
</div>
</div>

Pagination works from the second click

I have such a problem with pagination: it switches to another page only from the second click. When I click on page 2, it also remains on page 1, and only from the second time it switches to page 2. Also with the rest of the pages.
I did pagination component like this:
const Paginator = ({
total,
startPage = 1,
limit = 2,
totalPages = null,
onMovePage = null,
}) => {
const [hovered, setHovered] = useState(false);
const handleEnter = () => {
setHovered(true);
};
const handleLeave = () => {
setHovered(false);
};
const style = hovered ? { left: "-230px" } : {};
const [currentPage, setCurrentPage] = useState(startPage);
function range(start, stop, step) {
if(typeof stop=='undefined'){/*one param defined*/stop=start;start=0}
if(typeof step=='undefined'){step=1}
if((step>0&&start>=stop)||(step<0&&start<=stop)){return[]}
let result=[];
for(let i=start;step>0?i<stop:i>stop;i+=step){result.push(i)}
return result;
};
return (
<>
...
{range(1, totalPages+1).map(p => (
<PagItem key={p} handleClick={ () => {setCurrentPage(p); onMovePage && onMovePage({currentPage})} } title={p} name={p} />
))}
...
</>
}
And using it in softwares component:
const PER_PAGE = 2;
const Softwares = () => {
const [softwares, setSoftwares] = useState([]);
const [total, setTotal] = useState(null);
const [totalPages, setTotalPages] = useState(null);
const onFetchData = ({ currentPage }) => {
console.log('currentPage in onFetchData', currentPage)
fetch(`http://127.0.0.1:8000/api/software/?p=${currentPage}&per_page=${PER_PAGE}`)
.then(response => response.json())
.then(data => {
setSoftwares(data.results);
setTotal(data.count);
setTotalPages(data.total_pages);
})
}
useEffect(() => {
onFetchData({ currentPage: 1 })
}, []);
return (
<>
...
{softwares.map(s => (
<Article key={s.id} pathname={s.id} title={s.title} image={s.image} pubdate={s.pub_date} icon={s.category.parent.img} categoryID={s.category.id} categoryName={s.category.name} dCount={s.counter} content={s.content} />
))}
<Paginator totalPages={totalPages} total={total} onMovePage={onFetchData} limit={PER_PAGE} />
...
</>
);
};
So why is it happening?

Change the below
<PagItem key={p} handleClick={ () => {setCurrentPage(p); onMovePage && onMovePage({currentPage})} } title={p} name={p} />
to
<PagItem key={p} handleClick={ () => {setCurrentPage(p); onMovePage && onMovePage({currentPage:p})} } title={p} name={p} />
Because you're assuming your state currentPage is set by the time you call onMovePage which isn't true. Rely on the p to move to that page instead of state which will be set asynchronously.

How to display list of mapped array onClick - React

I have a component in which I am trying to add pagination functionality. I have made good progress in the structure so far. I have category buttons, where when a category button is selected, the element below shows a list of posts within that category.
For the pagination functionality, I using the WordPress REST API to pull in 5 posts at a time for each category. I am trying to create a "load more" button after the 5th post, where onClick it will load the next 5 posts:
const Posts = ({ state, actions }) => {
const [categories, setCategories] = useState([]);
const [categoryId, setCategoryId] = useState();
const [posts, setPosts] = useState([]);
useEffect(() => {
fetch(state.source.api + "/wp/v2/categories")
.then(response => response.json())
.then(data => {
setCategories(data);
})
}, []);
useEffect(() => {
if (categoryId) {
fetch(state.source.api + "/wp/v2/posts?categories=" + categoryId + "&per_page=5")
.then((response) => response.json())
.then((data) => {
setPosts(data);
});
}
}, [categoryId]);
const [morePosts, setMorePosts] = useState([]);
useEffect(() => {
if (categoryId) {
fetch(state.source.api + "/wp/v2/posts?categories=" + categoryId + "&per_page=5&page=" + 2)
.then((response) => response.json())
.then((data) => {
setMorePosts(data);
});
}
}, [categoryId]);
return (
<>
{categories.length > 0 ? (
categories.map((category, i) => {
return (
<button key={i} onClick={() => setCategoryId(category.id)}>{category.name}</button>
)
})
) : (
<p>Loading...</p>
)
}
<div>
{posts.length === 0 ? (
<p>No posts...</p>
) : (
<>
<ol>
{posts.map((post, i) => {
return (
<li key={i}>{post.title.rendered}</li>
)
})}
</ol>
<button onClick={() => setMorePosts(category.id)}>Load More</button>
{console.log(morePosts.map((post) => post.title.rendered))}
</>
)}
</div>
</>
)
}
As you can see, under the last button I am consoling the array, and it does return the next 5 posts for the selected category. I am stuck on how to turn that array from the console into actually being shown on the page.

I would do it this way:
Load more button changes the page number.
When page number is changed: useEffect fires and posts are refetched/rerendered based on page number param.
const [page, setPage] = useState(1);
const [posts, setPosts] = useState([]);
useEffect(() => {
if (!categoryId) {
return;
}
let url = `${state.source.api}/wp/v2/postscategories=${categoryId}&per_page=5"`;
if (page > 1) {
url += `&page=${page}`;
}
fetch(url)
.then((response) => response.json())
.then((data) => {
setPosts([...posts, ...data]);
});
}, [categoryId, page]);
<button onClick={() => { setPage(page + 1); }}>Load more</button>