A page list items, 10 by 10, with an infinite scroll.
Each item has a button "add to favorite", which when is pressed called the callback function handleClickFavorite, in order to not rerender items already rendered.
But, when handleClickFavorite is called, "data" are not fresh... If I had "data" dependency to handleClickFavorite = useCallback(async (item) => {...}, [user, data]);, "data" will be fresh, but each time I load more items, all items are rerended (I have a console.log into my Card PureComponent). So, how How can I do to use a fresh "data" in my handleClickFavorite without rerendered all my items please ?
const Home = () => {
const [user, setUser] = useState({ email: null, auth: false, favorites: [] });
const [data, setData] = useState([]);
const [isInfiniteDisabled, setInfiniteDisabled] = useState(false);
const config = useRef({
page: 0,
});
const loadData = (ev) => {
setInfiniteDisabled(true);
config.current.page += 1;
service.findAll(config.current.page).then(res => {
setData([
...data,
...res['items']
]);
});
}
useIonViewWillEnter(() => {
console.log('useIonViewWillEnter');
loadData();
});
const handleClickFavorite = useCallback(async (item) => {
if (user.auth) {
user.favorites.push(item.id);
setUser(user);
const datas = [...data];
for (let k in datas) {
if (datas[k].id === item.id) {
datas[k].rated = !datas[k].rated;
}
}
setData(datas);
} else {
// show login modal
}
}, [user]);
return (
<IonPage>
<IonContent fullscreen>
<IonList>
{data.map((item, index) => {
return <Card key={'card' + item.id} details={item} onClickFavorite={handleClickFavorite} />
})}
</IonList>
<IonInfiniteScroll
onIonInfinite={loadData}
threshold="100px"
disabled={isInfiniteDisabled}
>
<IonInfiniteScrollContent
loadingSpinner="bubbles"
loadingText="Loading more data..."
></IonInfiniteScrollContent>
</IonInfiniteScroll>
</IonContent>
</IonPage>
);
};
Related
this is a component that retrieve data from API and generate a table. One button in a column for removing the row opens a Modal.
For avoiding in first component render to trigger api.delete request, an useRef set as false in second useEffect
Modal's Delete button return row info in deleteHandler function which successfully trigger api.delete request on confirmation, remove user in backend however table is not reloading.
Once row is removed expected result is triggering api.get request and display table now updated and without row removed.
In order to get that result I tried with const [reload, setReload] = useState(false); state which introduce another dependency to both userEffect
reload state effectively reload table data updated however it cause also that api.delete request trigger with const ida undefined. Below component script it can find useEffect with my tried.
Any hint or possible solution is appreciated
import React, { Fragment, useEffect, useState, useRef } from "react";
... other imports ...
export default function AllUsers() {
const api = useApi();
const [userData, setUserData] = useState();
const [showModal, setShowModal] = useState(false);
const navigate = useNavigate();
const [modalMessage, setModalMessage] = useState();
const [removeUserId, setRemoveUserId] = useState();
const [ida, setIda] = useState();
let effectRan = useRef(false);
const [reload, setReload] = useState(false);
useEffect(() => {
(async () => {
const response = await api.get("/admin/users");
if (response.ok) {
setUserData(response.body);
} else {
setUserData(null);
}
})();
}, [api]);
useEffect(() => {
if (effectRan.current) {
// console.log("effect run");
(async () => {
const response = await api.delete("/admin/users", {
ida: ida,
});
if (response.ok && response.status === 204) {
console.log(response);
} else {
console.log(response.body.errors);
}
})();
}
return () => (effectRan.current = true);
}, [api, ida]);
const handleEditClick = (e, rowIndex) => {
// console.log("user/" + rowIndex.username);
navigate("/user/" + rowIndex.username, [navigate]);
};
const handleRemoveClick = (e, rowIndex) => {
// console.log([rowIndex]);
setShowModal(true);
setModalMessage({
title: `Remove ${rowIndex.username}`,
message: `User's email to remove ${rowIndex.email}`,
});
setRemoveUserId(rowIndex.id);
};
const closeHandler = () => {
setShowModal(false);
};
const deleteHandler = () => {
// console.log(removeUserId);
setIda(removeUserId);
setShowModal(false);
};
// console.log(ida, idb);
return (
<Fragment>
{showModal && (
<BtModal
show={showModal}
title={modalMessage.title}
message={modalMessage.message}
handleClose={closeHandler}
onConfirm={deleteHandler}
/>
)}
<Body>
<h1>User Table</h1>
{userData === undefined ? (
<Spinner animation="border" />
) : (
<>
{userData === null ? (
<p>Could not retrieve users.</p>
) : userData.length === 0 ? (
<p>There are not users in system</p>
) : (
<UserListTable
newData={userData}
handleEditClick={handleEditClick}
handleRemoveClick={handleRemoveClick}
/>
)}
</>
)}
</Body>
</Fragment>
);
}
useEffect updated with reload state:
useEffect(() => {
(async () => {
const response = await api.get("/admin/users");
if (response.ok) {
setUserData(response.body);
effectRan.current = false;
} else {
setUserData(null);
}
})();
}, [api, reload]);
useEffect(() => {
if (effectRan.current) {
// console.log("effect run");
(async () => {
const response = await api.delete("/admin/users", {
ida: ida,
});
if (response.ok && response.status === 204) {
console.log(response);
setReload(!reload);
} else {
console.log(response.body.errors);
}
})();
}
return () => (effectRan.current = true);
}, [api, ida, reload]);
Here you modify your last edit
const deleteHandler = () => {
// console.log(removeUserId);
setIda(removeUserId);
setReload(!reload)
setShowModal(false);
};
useEffect(() => {
(async () => {
const response = await api.get("/admin/users");
if (response.ok) {
setUserData(response.body);
} else {
setUserData(null);
}
})();
}, [api]);
useEffect(() => {
effectRan.current = reload;
if (effectRan.current) {
// console.log("effect run");
(async () => {
const response = await api.delete("/admin/users", {
ida: ida,
});
if (response.ok && response.status === 204) {
console.log(response);
setReload(!reload);
} else {
console.log(response.body.errors);
}
})();
}
return () => {
effectRan.current = false;
};
}, [api, ida, reload]);
It looks like you're trying to delete an item in the table and confirm it via a prompt. I can see that you've used a lot of useEffects, which might be making things a bit complicated.
Don't worry though, I have a solution that should be much simpler. Let me show you what I mean!
const Page = () => {
const [data, setData] = useState([]);
const [loading, setLoading] = useState([]);
const [deleting, setDeleting] = useState(false);
const [selectedItem, setSelectedItem] = useState(null);
const deleteHandler = async() => {
setDeleting(true);
await api.delete(selectedItem);
// Next you can either update the state itself
let tD = [...data];
const index = tD.findIndex((i) => i.id == selectedItem);
tD.splice(index, 1);
setSelectedItem(tD);
// or refetch data from the backend and update the state
const d = await api.getData();
setData(d);
setDeleting(false);
setSelectedItem(null);
};
useEffect(() => {
const fetchData = async() => {
setLoading(true);
const d = await api.getData();
setData(d);
setLoading(false);
}
fetchData();
}, [])
return loading ? <div>Loading...</div> : <>
{/*Other JSX elements*/}
{selectedItem && <div>
{/*prompt body*/}
<button onClick={() => {setSelectedItem(null)}}>Cancel</button>
<button disabled={deleting} onClick={() => {deleteHandler()}}>Delete</button>
{/*Button will be disabled when the DELETE request is sent*/}
</div>}
{data.map((row) => {
return <tr key={row.id}>
<td>...</td>
<td>...</td>
<td>
<button onClick={setSelectedItem(row.id)}>Delete</button>
</td>
</tr>
})}
</>
}
I'm getting data from Django Rest API and React for Frontend, and I need to create the pagination with posts. I did it all in pagination component. I created the state with current page and I'm changing it by clicking on the page button in component like this:
const Paginator = () => {
const [count, setCount] = useState(null);
const [currentPage, setCurrentPage] = useState(1);
const [totalPages, setTotalPages] = useState(null);
const [nextPage, setNextPage] = useState(null);
const [previousPage, setPreviousPage] = useState(null);
const [valid, setValid] = useState(false);
useEffect(() => {
fetch(`http://127.0.0.1:8000/api/software/?p=${currentPage}`)
.then(response => response.json())
.then(data => {
setCount(data.count);
setTotalPages(data.total_pages)
setNextPage(data.links.next);
setPreviousPage(data.links.previous);
setValid(true);
})
}, [currentPage]);
...
return (
<>
{
...
<PbStart style={style} totalPages={range(1, totalPages+1)} setCurrentPage={setCurrentPage} />
...
}
</>
);
};
const PagItem = ({key, handleClick, className, title, name }) => {
return (
<li key={key} onClick={handleClick}>
<Link to='/' className={className} title={`Go to page ${title}`}>
{name}
</Link>
</li>
);
};
const PbStart = ({ style, totalPages, setCurrentPage }) => {
return (
...
{totalPages.map(p => (
<PagItem key={p} handleClick={() => setCurrentPage(p)} title={p} name={p} />
))}
...
);
};
And in posts component I don't know how to change current page, or getting it from the paginaton component. I've written that like this:
const Softwares = () => {
const [softwares, setSoftwares] = useState([]);
const [currentPage, setCurrentPage] = useState(1);
const [valid, setValid] = useState(false);
useEffect(() => {
fetch(`http://127.0.0.1:8000/api/software/?p=${currentPage}`)
.then(response => response.json())
.then(data => {
setSoftwares(data.results);
setValid(true);
})
}, [currentPage]);
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} />
))}
...
}
</>
);
};
So, how to do that(get the current page from pagination component or another way)?
I think a Paginator's job is only moving between pages and updating current page state. It should not be fetching data by itself, you can provide functionality to do extra work with props.
I haven't tested this, but this might be a good starting point.
With the example below you'll have a list of articles and then below it next and previous buttons.
In Softwares, as you can see I am passing the same function for handling next and previous pages, you can refactor it to have one function like onPageMove and call this function handleNext and handlePrev.
I added two separate functions if you have want to handle something different in either.
const Paginator = ({
total, // Required: Total records
startPage = 1, // Start from page / initialize current page to
limit = 30, // items per page
onMoveNext = null, // function to call next page,
onMovePrev = null, // function to call previous page
}) => {
const [currentPage, setCurrentPage] = useState(startPage);
const canGoNext = total >= limit;
const canGoPrev = currentPage > 1;
function handleNext(e) {
if (canGoNext) {
setCurrentPage((prevState) => prevState+1);
onMoveNext && onMoveNext({ currentPage });
}
}
function handlePrev(e) {
if (canGoPrev) {
setCurrentPage((prevState) => prevState-1);
onMovePrev && onMovePrev({ currentPage });
}
}
return (
<div>
<button onClick={handlePrev} disabled={!canGoPrev}>Prev</button>
<button onClick={handleNext} disabled={!canGoNext}>Next</button>
</div>
);
};
Here is how you can use Paginator in other components.
const PER_PAGE = 30; // get max # of records per page
const Softwares = () => {
const [softwares, setSoftwares] = useState([]);
const [valid, setValid] = useState(false);
const 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);
setValid(true);
})
}
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 total={softwares.length} limit={PER_PAGE} onMoveNext={onFetchData} onMovePrev={onFetchData} />
</>
);
};
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.
I have created a table in which I would now like to be able to delete individual rows. The button is displayed and can be clicked, but the deleteItmen function is not called. Unfortunately I'm quite new to React.js and haven't found a solution yet.
const Tab = (props) => {
const [showContent, setShowContent] = useState([]);
const [loading, setLoading] = useState(false);
const token = getUser.getCurrentUser().token;
useEffect(() => {
LoadTable();
// eslint-disable-next-line
}, []);
const LoadTable = () => {
if (props.table === undefined)
getData("device", setShowContent, setLoading);
else getData(props.table, setShowContent, setLoading);
};
const getHeader = () => {
return <tr>{showContent[0].map((elem, index) => <th>{elem}</th>)}</tr>
}
const getBody = () => {
const bodylist = Object.values(showContent.slice(1));
const body = bodylist.map((elem, index) => ({ ...elem, button: (<button onclick={() => deleteItem(elem.id)}>Delete</button>) }))
return body.map((row, index) => <tr> {Object.values(row).map((elem, i) => <td> {elem}</td>)} </tr>)
}
const deleteItem = async (id) => {
await axios.delete('http://localhost:3000/api/' + id, { tablename: props.table }, {
headers: {
"x-access-token": token,
},
})
LoadTable();
}
return (
<div>
{!loading ?
<h1>Loading</h1> :
<table>
<thead>{getHeader()}</thead>
<tbody>{getBody()}</tbody>
</table>
}
</div>
);
I have a main screen where you can see multiple items displayed in card form you can access an item by pressing it to see its details, on the details screen I added a bookmark option that save the item using async storage, you can also check the saved items on a different screen called savedItems screen.
The problem is :
when i bookmark an item it get saved properly and i can go to the savedItems screen and find it there, but some times i have to reload the app for the item to appear on the savedItems screen why is that ?
if i book multiple items they all get saved ( on console.log ) but only the last one appears for some reason i never get more then one item displayed on the SavedItems screen
Bellow is snippets of the code used to book mark ( saved an item on its details screen )
Details.js
const DetailScreen = (props) => {
const [saved, setSaved] = useState([]);
const [items, setItems] = useState(props.route.params);
const onSave = (item) => {
const newItems = [...saved, item];
setSaved(newItems);
const items = JSON.stringify(newItems);
SaveItem("saved", items).then((res) => {
console.log("saved", res);
});
};
const goToDetails = () => {
setSaved([]);
props.navigation.navigate("SaveScreen");
};
const { width, height } = Dimensions.get("window");
const { data } = props.route.params; // this returns the data from each article
//ReadItem("saved").then((res) => console.log(res));
return (
<TouchableOpacity
...
onPress={() => {
onSave(data);
}}
>
<MaterialCommunityIcons
name="bookmark"
size={35}
color={colors.shade2}
/>
</TouchableOpacity>
)
SaveScreen.js
export default class Details extends Component {
state = {
saved: [],
};
removeItem = () => {
DeleteItem("saved")
.then((res) => {
this.setState({
saved: [],
});
console.log(res);
})
.catch((e) => console.log(e));
};
componentDidMount = () => {
ReadItem("saved")
.then((res) => {
if (res) {
const saved = JSON.parse(res);
this.setState({
saved: saved,
});
}
})
.catch((e) => console.warn(e));
};
render() {
return (
<View style={styles.container}>
<FlatList
keyExtractor={(item, index) => index.toString()}
data={this.state.saved}
renderItem={({ item }) => {
return (
<TouchableScale
activeScale={0.9}
tension={50}
friction={7}
useNativeDriver
onPress={() =>
this.props.navigation.navigate("DetailScreen", { data: item })
}
>
<Card item={item} />
</TouchableScale>
);
}}
/>
{this.state.saved.length > 0 && (
<TouchableOpacity onPress={this.removeItem} style={styles.button}>
<Text style={styles.save}>Remove Key</Text>
</TouchableOpacity>
)}
</View>
);
}
}
the code used to save data using async storage
Dbhelper.js
import { AsyncStorage } from "react-native";
export const SaveItem = async (key, value) => {
try {
await AsyncStorage.setItem(key, value);
console.log("saved");
} catch (e) {
console.log(e);
}
};
export const ReadItem = async (key) => {
try {
var result = await AsyncStorage.getItem(key);
return result;
} catch (e) {
return e;
}
};
export function MultiRead(key, onResponse, onFailure) {
try {
AsyncStorage.multiGet(key).then((values) => {
let responseMap = new Map();
values.map((result, i, data) => {
let key = data[i][0];
let value = data[i][1];
responseMap.set(key, value);
});
onResponse(responseMap);
});
} catch (error) {
onFailure(error);
}
}
export async function DeleteItem(key) {
try {
await AsyncStorage.removeItem(key);
return true;
} catch (exception) {
return false;
}
}
if i book multiple items they all get saved ( on console.log ) but only the last one appears for some reason i never get more then one item displayed on the SavedItems screen
I think the problem is when you save new item you remove old items. You have to read old items when you mount DetailScreen. Or you can read items inside onSave method. It's more safety. It depends your application architecture
const DetailScreen = (props) => {
const [items, setItems] = useState(props.route.params);
const onSave = (item) => {
let saved = [];
ReadItem("saved")
.then((res) => {
if (res) {
saved = JSON.parse(res);
}
const newItems = [...saved, item];
const items = JSON.stringify(newItems);
SaveItem("saved", items).then((res) => {
console.log("saved", res);
});
})
.catch((e) => console.warn(e));
};
const goToDetails = () => {
setSaved([]);
props.navigation.navigate("SaveScreen");
};
const { width, height } = Dimensions.get("window");
const { data } = props.route.params; // this returns the data from each article
//ReadItem("saved").then((res) => console.log(res));
return (
<TouchableOpacity
...
onPress={() => {
onSave(data);
}}
>
<MaterialCommunityIcons
name="bookmark"
size={35}
color={colors.shade2}
/>
</TouchableOpacity>
)
when i bookmark an item it get saved properly and i can go to the savedItems screen and find it there, but some times i have to reload the app for the item to appear on the savedItems screen why is that ?
I have only one idea why it may happens. In some cases, you don't unmount SaveScreen. When you return to the SaveScreen componentDidMount is not called. Just try to add console.log to componentDidMount and when you reproduce this behavior if console.log is missed it means you SaveScreen wasn't unmounted
To handle all cases you can try to do that:
export default class Details extends Component {
state = {
saved: [],
};
removeItem = () => {
DeleteItem("saved")
.then((res) => {
this.setState({
saved: [],
});
console.log(res);
})
.catch((e) => console.log(e));
};
componentDidMount = () => {
this.readItems();
this.unsubscribe = navigation.addListener('focus', this.readItems);
};
componentWillUnmount() {
this.unsubscribe();
}
readItems = () => {
ReadItem("saved")
.then((res) => {
if (res) {
const saved = JSON.parse(res);
this.setState({
saved: saved,
});
}
})
.catch((e) => console.warn(e));
}
render() { ... }
}