I am new to react & JS. I need to sync data to db and use what i got from db render to UI.
Flow: CRUD in infra => sync data to db => use data from db and render to UI.
But the second function always completes first when syncDB still in status "pending". So if I detete all my db and run in very first time, I will get nothing in UI.
This is how I code:
[Sync data to db]
useEffect(async () => {
const syncDB = async () => {
await Api.post(syncLocalDisk({vpcId, instanceId}))
}
syncDB()
}, [])
const {data, isLoading, isRefetching, error, refetch} = useQuery(
['instance-storages', vpcId, instanceId],
() => {
const url = `${instanceStorages({
vpcId,
instanceId,
})}`
return Api.get(url)
},
)
How can I make sure it's syncDB first?
I have tried sync DB inside useQuery but it does not seems very logicial.
useEffect(async () => {
const syncDB = async () => {
await Api.post(syncLocalDisk({vpcId, instanceId}))
}
await syncDB()
}, [])
Try this.
Related
I have the following code in my React component:
const { id } = useParams();
const { tripData, facilityData } = useContext(AppContext);
const [data, setData] = useState([]);
useEffect(() => {
const idResults = facilityData.filter(facility => facility.id === id);
if (idResults.length > 0) {
setData(idResults[0]);
}
}, [])
Where:
[data, SetData] is the state that is used to handle populating a container
facilityData is data accessed from my app context
id is accessed from the URL
What seems to happen is that the data loads the first time without fault, but it errors out when hosted on the actual site (on localhost, it waits and eventually loads). To try to get a better idea of what was happening, I tried the following code:
const { id } = useParams();
const { tripData, facilityData } = useContext(AppContext);
const [data, setData] = useState([]);
useEffect(() => {
const idResults = facilityData.filter(facility => facility.id === id);
if (idResults.length > 0) {
setData(idResults[0]);
} else if (idResults.length === 0) {
console.log(`id: ${id}`)
console.log(`len: ${idResults}`)
}, [])
On localhost, on refresh, it console logs the actual id but then console logs the empty array before finally loading the data.
What I'm wondering is why this is the observed behavior. The "id" value seems to be constantly available, but the filter doesn't seem to run prior to the site loading. Is there a way to prevent this?
EDIT:
This is how I get the data (from Firebase)
App.js
import { collection, getDocs } from "firebase/firestore";
import { db } from "./firebase";
const [truckData, setTruckData] = useState([]);
const [facilityData, setFacilityData] = useState([]);
const [tripData, setTripData] = useState([]);
useEffect(() => {
const fetchData = async (resource, setter) => {
let list = [];
try {
const querySnapshot = await getDocs(collection(db, resource));
querySnapshot.forEach((doc) => {
let docData = doc.data();
if (resource === "trips") {
docData.startDate = docData.startDate.toDate();
docData.endDate = docData.endDate.toDate();
}
list.push({ id: doc.id, ...docData });
});
setter(list);
} catch (error) {
console.log(error);
}
};
fetchData("trucks", setTruckData);
fetchData("facilities", setFacilityData);
fetchData("trips", setTripData);
}, []);
The app is at logi-dashboard, if that helps any.
EDIT Turns out the issue was with my hosting service, not the project. Go figure.
Based on my understanding, it seems like the facilityData on which you are trying to apply filter and which is coming from AppContext(Context hook variable) is found to be empty array when the useEffect code is getting executed, this might be scene if you are hitting any API to get the data into facility but the API response is not coming till the time useEffect is getting executed or any other source which is not populating the facilityData until useEffect runs.
In that case, you can add facilityData in the dependency array of useEffect, which will help the useEffect execute again once the facilityData is populated(updated)
I am trying to fetch some user data from Firebase using getDoc and some data from MongoDB using axios in React.js.
Code:
async function getSolvedProblems() {
const docRef = await doc(db, "users-progress", user.uid);
await getDoc(docRef).then((doc) => {
console.log(doc.data());
});
}
useEffect(() => {
//fetch user's solved problems from firebase
getSolvedProblems();
//fetch problems from db server
axios
.get(process.env.REACT_APP_BACKEND_URL)
.then((res) => {
//doing something here
})
.catch((err) => {
console.log(err);
});
}, []);
But I don't know why the firebase data is not getting logged in console, when I hit refresh. But when I make any change in code, and save it, then it gets logged. I am unable to understand how useEffect is working here.
This is use effect work on below:
useEffect(() => {
//Runs only on the first render
}, []);
Also, you need to handle the catch block in your getSolvedProblems() method, see is there any error there.
On my guess, there is no value on user.uid when you load on page render
So I'm currently brushing up my react skills and learning firebase. I found it simple enough to configure and now I have been successfully making fetch requests from my realtime database.
I am currently building some sort of a birthday app that would show monthly and daily celebrants, and have generated mock data that I imported into my database. Currently, the first names are being fetched successfully and displaying on the screen, however the images (that are hosted on another site and fetched as a string from the db) are not loading properly and I'm getting 500 error in my console. If I keep refreshing though, they eventually load.
I'm thinking it must be with the way I make my fetch request. I basically fetch all users and then make a filter (have not explored fetching with queries yet) so I thought it would work.
This is the code for the fetch requests.
export const getUsers = () => {
const usersDb = ref(database);
return get(child(usersDb, `/users`)).then((snapshot) => {
return snapshot.val();
});
};
export const getMonthlyCelebrants = async () => {
const users = await getUsers();
const monthlyCelebs = [];
for (let user in users) {
const userMonth = +users[user]["birth_date"].split("/")[1];
userMonth === getMonthNum() && monthlyCelebs.push(users[user]);
}
return monthlyCelebs;
};
And this is the Monthly Celebrants component I use them in:
export default function Monthly() {
const [monthlyCelebs, setMonthlyCelebs] = useState([]);
const [isLoading, setIsLoading] = useState(true);
useEffect(() => {
async function loadPage() {
setIsLoading(true);
const users = await getMonthlyCelebrants();
setIsLoading(false);
setMonthlyCelebs(users);
}
loadPage();
}, []);
return (
<div>
<h2>{getMonthAndYear()} Celebrants</h2>
{isLoading ? (
<p>Celebrants loading...</p>
) : (
sortBirthdays(monthlyCelebs).map((monthlyCeleb) => {
return (
<SingleMonthlyCelebrant
monthlyCeleb={monthlyCeleb}
key={`${monthlyCeleb.birth_date}${monthlyCeleb.first_name}`}
/>
);
})
)}
</div>
);
}
Any tips or advice would be greatly appreciated. Thank you!
Hi guys hoping someone can help me with an issue. I built a function that fetches user posts from backend and returns them as a response:
const [posts, setPosts] = useState([]);
const newsFeed = async () => {
await axios
.post(`${process.env.REACT_APP_API}/news-feed`)
.then((res) => {
setPosts(res.data);
})
.catch((err) => {
console.log(err);
});
};
This function gets called by useEffect and also whenever a post is submitted, liked, commented on etc. so that users' posts are always re-rendered every time they are modified or added.
It was working fine until I decided to implement Infinite Scroll to my application. I installed the npm package react-infinite-scroll-component and modified my function to look like this:
const [posts, setPosts] = useState([]);
const [page, setPage] = useState(1);
const newsFeed = async () => {
await axios
.post(
`${process.env.REACT_APP_API}/news-feed/${page}`)
.then((res) => {
let newPosts = posts;
newPosts = newPosts.concat(res.data);
setPosts(newPosts);
setPage(page + 1);
})
.catch((err) => {
console.log(err);
});
};
The infinite scroll is working just fine but now the posts are not being re-rendered every time this function gets called and instead I need to refresh the page to see changes. I tried resetting the state of page back to 1 again on my postSubmit/likeHandler functions but this didn't have any effect. I'm not seeing any errors in the console so am unsure what is going on.
Replace let newPosts = posts; with let newPosts = [...posts]; Passing the same array reference to setState will not cause an update, since the value hasn't changed. By using [...posts], you are creating a new array, causing the component to update.
I'm building a web application that consumes TMDB Api. I have the following code that fetch all information about a TV Show
export const useShowInfoFetch = ({showId}) => {
const [data, setData] = useState({})
const [loading, setLoading] = useState(false)
const [_error, _setError] = useState(false)
const fetchShowInfo = useCallback(() => {
setLoading(true)
try {
axios.get(getShowInfo(showId))
.then(response => {
setData(response.data)
})
} catch (error) {
_setError(true)
} finally {
setLoading(false)
}
}, [showId])
useEffect(() => {
fetchShowInfo()
}, [fetchShowInfo])
return [data, loading, _error]
}
All the information fetched is displayed in page, that also has Links with react-router-dom. Those links goes to another tv show page.
The problem is that when I'm in a page with a tv show that has X amount of seasons and I click a tv show with less seasons, the seasons from the page I was are persisting for a little bit of time. So, when I fetch the information for each season I got a 404 in the page that has less seasons.
Here is a screenshot of the error
The orange circle is what it's displayed since I click the tv show with less seasons.
As you can see, the seasons from the previous page are persisting for a little time, and because The Alienist has only 2 seasons (not 9) I get the 404. You can also note that latter, the correct amount of seasons are displayed.
I've tried to add a cleanup method in the useEffect hook. Something like this:
useEffect(() => {
fetchShowInfo()
return function cleanup() {
setData({})
}
}, [fetchShowInfo])
But this did not work.
I know that I can handle that with a catch after the then Axios promise, but I want to figure out why this is happening and fix the issue with a good solution instead of avoiding it.
Any help is welcomed and I can share the repository with all the code if needed.
EDIT:
To display the similar movies I use another custom hook
export const useSimilarFetch = (elementType, elementId) => {
const [similarElements, setSimilarElements] = useState({elements: []})
const [similarLoading, setSimilarLoading] = useState(false)
const [_error, _setError] = useState(false)
const fetchSimilarElements = useCallback(async (endpoint) => {
console.log(">>> fetching similar elements <<<")
setSimilarLoading(true)
try {
await axios.get(endpoint)
.then(response => {
setSimilarElements(() => ({
elements: [...response.data.results],
currentPage: response.data.page,
totalPages: response.data.total_pages
}))
})
} catch (error) {
_setError(true)
} finally {
setSimilarLoading(false)
}
}, [])
useEffect(() => {
fetchSimilarElements(getSimilar(elementType, elementId));
}, [fetchSimilarElements, elementType, elementId])
return [{similarElements, similarLoading, _error}, fetchSimilarElements]
}
Then, in my ShowInfoComponent I call all the needed hooks like this:
const {showId} = useParams()
const [data, loading, _error] = useShowInfoFetch({showId})
const [{similarElements, similarLoading}] = useSimilarFetch("tv", showId)
Thanks.
By the time showId changes, data has to wait one additional render cycle, so showId is already used even though data has not yet been fetched. The UI relies on both showId and data, yet data depends on showId. One way to solve this could be having your UI to rely on data alone. What about the id? Add it to data for example. We merely want to avoid the desynchronization.
Something like this:
export const useShowInfoFetch = ({showId}) => {
const [data, setData] = useState({})
const [loading, setLoading] = useState(false)
const [_error, _setError] = useState(false)
const fetchShowInfo = useCallback(() => {
setLoading(true)
try {
axios.get(getShowInfo(showId))
.then(response => {
setData({ id: showId, info: response.data})
})
} catch (error) {
_setError(true)
} finally {
setLoading(false)
}
}, [showId])
useEffect(() => {
fetchShowInfo()
}, [fetchShowInfo])
return [data, loading, _error]
}
Then use data.id to build your links.
If response.data already contains the id, then even better, use that.
That's just an example, of course but hopefully you get the idea.
I might be wrong but I believe you are not watching the correct value on the useEffect. You should be watching showId and not the function fetchShowInfo. That is:
useEffect(() => {
fetchShowInfo()
}, [showId]) --> HERE
And as you are memoized the callback, if you are watching the wrong variable then you will get back the 'last answered'.