I was following this tutorial https://www.sitepoint.com/reddit-clone-react-firebase/.
Earlier it was really simple just call onSnapshot after the document is fetched, but here it is a separate function, and now here comes the issue, when I try to call that onSnapshot by passing document, but it always says,no matter what type of data I tried to pass it as the first param, it always says, it is not type of 'bc' which it expects.
FirebaseError: Expected type 'bc', but it was: a custom he object
useEffect(async () => {
const postsCollection = collection(db, "posts");
const orderedCollection = query(
postsCollection,
orderBy("createdAt", "desc")
);
try {
onSnapshot(
orderedCollection, // here I think the problem is!
(querySnapshot) => {
console.log("yahaan se problem hai");
console.log(querySnapshot);
const _posts = [];
querySnapshot.forEach((doc) => {
console.log(doc);
_posts.push({
id: doc.id,
...doc.data(),
});
});
console.log(_posts);
// setPosts(_posts);
},
(error) => {
console.log("error occured: ", error);
},
() => {
console.log("completed");
}
);
} catch (e) {
console.log("ye kya drama hai:", e);
} finally {
console.log("finally");
}
}, []);
Okey, so I had the same problem and I found a solution after struggling with the newest version of firebase for a while.
I don't know if you're using a class component or a functional one, in this example i'm using a funcional component but I assume it'll work the same if you replace the react hooks.
import { getFirestore, collection } from 'firebase/firestore'
const db = getFirestore();
const colRef = collection(db, "team")
const [results, setResults] = useState([]);
useEffect(() => {
let isMounted = true;
onSnapshot(colRef, (snapshot) => {
if (isMounted) {
const results= snapshot.docs.map((doc) => {return {...doc.data(), id: doc.id}});
setResults(results)
}
});
return () => { isMounted = false };
}, []);
This way your component'll listen to updates everytime the data changes, after that you can personalize it using querys but i wanted to show you a simple example so it's easy to understand.
I had the same problem, unfortunately, the above didn't help me. in my case I was actually importing form functions and types from '#firebase/firestore' and others from 'firebase/firestore'... this was done by autoImport. the moment I made all of them get the types and functions from the same place it worked instantly
These kind of errors occur usually when the functions aren't used the way they're supposed to. I can't really tell where the problem comes from in your code but you may try the getDocs method instead and a state variable to store your values
try this code.
const [Results, setResults] = useState([]);
useEffect(() => {
const FetchedPosts = async () => {
const querySnapshot = await getDocs(
collection(db, 'posts'),
orderBy("createdAt", "desc")
);
querySnapshot.forEach((doc) => {
setResults((prevState) => [...prevState, doc.data()]);
});
};
FetchedPosts();
}, []);
Related
I am trying to list the data of each document that i am fetching from a firebase query, However I am being able to show the data through flatlist, Iwoudl love to iterate the data in another way in order to add it to a PDF that will be created from the app.
const [Annotations, setAnnotations] = useState(null);
useEffect(() => {
const q = query(
collection(db, "notifications"),
orderBy("createdAt", "desc")
);
console.log("Query:");
console.log(q);
onSnapshot(q, (test) => {
setAnnotations(test.docs);
});
}, []);
From the code above I am getting some unneccesary data, however I’d like to get the data of the document, hope you help me, thanks!
What you're seeing are the internals of the Firestore DocumentSnapshot and QueryDocumentSnapshot classes, which is indeed pretty meaningless.
If you only want to use the data:
onSnapshot(q, (test) => {
setAnnotations(test.docs.map((doc) => doc.data()));
});
If you want the data and document ID:
onSnapshot(q, (test) => {
setAnnotations(test.docs.map((doc) => { doc.id, ...doc.data() }));
});
I'm building an app using react-native and react-native-firebase and i'm running into an issue while trying to implement a comment section.
My tree of data is currently like that :
collection(comments)/doc(currentUser.uid)/collection(userComments)/doc(commentCreatorID)
Within this doc commentCreatorID there is all the data i need. So basically the content, a timestamp...
For this part everything works perfectly but in order to havethe commentCreator's infos stick with his post, i need to grab them somewhere else.
The way i do that is taking the doc(commentCreatorID), as it is the uid of this user and ask firestore to give me the data from the document with this same id within my "users" collection.
Here is my code :
const [comments, setComments] = useState([])
const [commentsReady, setCommentsReady] = useState([])
useEffect(() => {
setComments([])
setLoading(true)
firestore()
.collection('comments')
.doc(auth().currentUser.uid)
.collection('userComments')
.get()
.then((snapshot) => {
let comments = snapshot.docs.map(doc => {
const data = doc.data()
const id = doc.id
return {id, ...data}
})
setComments(comments)
})
.then(() => {
comments.forEach(comment => {
firestore()
.collection("users")
.doc(comment.id)
.get()
.then((snapshot) => {
const data = snapshot.data()
setCommentsReady({comments, ...data})
})
})
})
console.log(commentsReady)
setLoading(false)
}, [handleScroll4])
This doesn't seem to works well as for now. My log throw an empty array right into my face..
I'm grabbing each comment correctly tho and even each user's data corresponding to their uids.
I can log them once ForEach have been done.
But for some reason i can't have them set to my state commentsReady.
Did i miss something ?
Thanks for your time
The setters that the useState function returns are async. Copying data from one state to another is also an antipattern. Try using effects.
const TT = () => {
const [comments, setComments] = useState([]);
const [userInfos, setUserInfos] = useState([]);
const commentsView = comments.map(comment => {
// Reactively merge each comment with the appropriate user info
});
useEffect(() => {
firestore()
.collection('comments')
.doc(auth().currentUser.uid)
.collection('userComments')
.get()
.then((snapshot) => {
let comments = snapshot.docs.map(doc => {
const data = doc.data()
const id = doc.id
return {id, ...data}
});
setComments(comments);
});
}, []);
useEffect(async () => {
// Maybe keep a cache of fetched user datas, but not sure how this is architected
const snapshots = await Promise.all(comments.map(comment => {
return firestore()
.collection("users")
.doc(comment.id)
.get();
}));
setUserInfos(snapshots.map(snap => snap.data()));
}, [comments]);
};
I'm trying to replace below code (ver8) to firebase SDK ver9 (modular style). but no success so far.
useEffect(() => {
const unsub = db
.collection("posts")
.doc("postId")
.collection("comments")
.orderBy("timestamp", "desc")
.onSnapshot((snapshot) => {
//update some state
});
return () => {
unsub();
};
}, []);
I tried to use query to access this sub collection together with orderBy by refer to following official example but couldn't find working solution, especially how to handle sub collection reference in query. (how can I realize "collection().doc().collection().orderBy().onSnapshot" in ver9 ?)
I'm really appreciated if someone give me a hint. BR
https://firebase.google.com/docs/firestore/query-data/listen
https://firebase.google.com/docs/firestore/query-data/order-limit-data
As far as I can see in the documentation for the collection function, you can pass in the entire path as a string.
So that should be something like:
...
const db = getFirestore();
const commentsRef = doc(db, "posts", postId, "comments");
#Frank-san Thank you very much for your hint. Now everything working fine with full path arguments (your hint) as like below.
useEffect(() => {
const q = query(
collection(db, "posts", props.postId, "comments"),
orderBy("timestamp", "desc")
);
const unSub = onSnapshot(q, (snapshot) => {
//Some process
});
return () => {
unSub();
};
}, []);
Thanks again and have a good day !
I have this data from firestore and I wanted to retrieve it dynamically with a where() but this is the error I'm getting:
TypeError: vaccines is not a function
The user collection:
[![enter image description here][1]][1]
Below are the codes:
const Vaccine = () => {
const [vaccines, setVaccines] = useState([]);
useEffect(() => {
const unsubscribe = firestore
.collection("vaccines")
.onSnapshot((snapshot) => {
const arr = [];
snapshot.forEach((doc) =>
arr.push({
...doc.data(),
id: doc.id,
})
);
setVaccines(arr);
});
return () => {
unsubscribe();
};
}, []);
Preface
As highlighted in the comments on the original question, this query structure is not advised as it requires read access to sensitive user data under /users that includes private medical data.
DO NOT USE THIS CODE IN A PRODUCTION/COMMERICAL ENVIRONMENT. Failure to heed this warning will lead to someone suing you for breaches of privacy regulations.
It is only suitable for a school project (although I would a fail a student for such a security hole) or proof of concept using mocked data. The code included below is provided for education purposes, to solve your specific query and to show strategies of handling dynamic queries in React.
From a performance standpoint, in the worst case scenario (a cache miss), you will be billed one read, for every user with at least one dose of any vaccine, on every refresh, for every viewing user. Even though your code doesn't use the contents of any user document, your code must download all of this data too because the Client SDKs do not support the select() operator.
For better security and performance, perform this logic server-side (e.g. Cloud Function, a script on your own computer, etc) and save the results to a single document that can be reused by all users. This will allow you to properly tighten access to /users. It also significantly simplifies the code you need to display the graphs and live statistics on the client-side.
useEffect
As stated by the React documentation on the Rules of hooks:
Only Call Hooks at the Top Level
Don’t call Hooks inside loops, conditions, or nested functions. Instead, always use Hooks at the top level of your React function, before any early returns. By following this rule, you ensure that Hooks are called in the same order each time a component renders. That’s what allows React to correctly preserve the state of Hooks between multiple useState and useEffect calls.
The documentation further elaborates that React relies on the order in which Hooks are called, which means that you can't have hook definitions behind conditional logic where their order and quantity changes between renders. If your hooks rely on some conditional logic, it must be defined inside of the hook's declaration.
As an example, if you have an effect that relies on other data, with this logic:
const [userProfile, setUserProfile] = useState();
const [userPosts, setUserPosts] = useState(null);
useEffect(() => {
// get user profile data and store in userProfile
}, []);
if (userProfile) {
useEffect(() => {
// get user post list and store in userPosts
}, [userProfile]);
}
you need to instead use:
const [userProfile, setUserProfile] = useState();
const [userPosts, setUserPosts] = useState(null);
useEffect(() => {
// get user profile data and store in userProfile
}, []);
useEffect(() => {
if (!userProfile) {
// not ready yet/signed out
setUserPosts(null);
return;
}
// get user post list and store in userPosts
}, [userProfile]);
Similarly, for arrays:
someArray && someArray.forEach((entry) => {
useEffect(() => {
// do something with entry to define the effect
}, /* variable change hooks */);
});
should instead be:
useEffect(() => {
if (!someArray) {
// not ready yet
return;
}
const cleanupFunctions = [];
someArray.forEach((entry) => {
// do something with entry to define an effect
cleanupFunctions.push(() => {
// clean up the effect
});
});
// return function to cleanup the effects created here
return () => {
cleanupFunctions.forEach(cleanup => cleanup());
}
}, /* variable change hooks */);
Because this looks a lot like lifecycle management, you are actually better off replacing it with nested components rather than using hooks, like so:
return (
<> // tip: React.Fragment shorthand (used for multiple top-level elements)
{
someArray && someArray
.map(entry => {
return <Entry key={entry.key} data={entry.data} />
})
}
</>
);
Adapting to your code
Note: The code here doesn't use onSnapshot for the statistics because it would cause a rerender every time a new user is added to the database.
const getVaccineStats = (vaccineName) => {
const baseQuery = firestore
.collection("users")
.where("doses.selectedVaccine", "==", vaccine);
const oneDoseQueryPromise = baseQuery
.where("doses.dose1", "==", true)
.where("doses.dose2", "==", false)
.get()
.then(querySnapshot => querySnapshot.size);
const twoDoseQueryPromise = baseQuery
.where("doses.dose1", "==", true)
.where("doses.dose2", "==", true)
.get()
.then(querySnapshot => querySnapshot.size);
return Promise.all([oneDoseQueryPromise, twoDoseQueryPromise])
.then(([oneDoseCount, twoDoseCount]) => ({ // tip: used "destructuring syntax" instead of `results[0]` and `results[1]`
withOneDose: oneDoseCount,
withTwoDoses: twoDoseCount
}));
};
const Vaccine = () => {
const [vaccines, setVaccines] = useState();
const [vaccineStatsArr, setVaccineStatsArr] = useState([]);
// Purpose: Collect vaccine definitions and store in `vaccines`
useEffect(() => {
return firestore // tip: you can return the unsubscribe function from `onSnapshot` directly
.collection("vaccines")
.onSnapshot({ // tip: using the Observer-like syntax, allows you to handle errors
next: (querySnapshot) => {
const vaccineData = []; // tip: renamed `arr` to indicate what the data contains
querySnapshot.forEach((doc) =>
vaccineData.push({
...doc.data(),
id: doc.id,
});
);
setVaccines(vaccineData);
}),
error: (err) => {
// TODO: Handle database errors (e.g. no permission, no connection)
}
});
}, []);
// Purpose: For each vaccine definition, fetch relevant statistics
// and store in `vaccineStatsArr`
useEffect(() => {
if (!vaccines || vaccines.length === 0) {
return; // no definitions ready, exit early
}
const getVaccineStatsPromises = vaccines
.map(({ vaccine }) => [vaccine, getVaccineStats(vaccine)]);
// tip: used "destructuring syntax" on above line
// (same as `.map(vaccineInfo => [vaccineInfo.vaccine, getVaccineStats(vaccineInfo.vaccine)]);`)
let unsubscribed = false;
Promise.all(getVaccineStatsPromises)
.then(newVaccineStatsArr => {
if (unsubscribed) return; // unsubscribed? do nothing
setVaccineStatsArr(newVaccineStatsArr);
})
.catch(err => {
if (unsubscribed) return; // unsubscribed? do nothing
// TODO: handle errors
});
return () => unsubscribed = true;
}, [vaccines]);
if (!vaccines) // not ready? hide element
return null;
if (vaccines.length === 0) // no vaccines found? show error
return (<span class="error">No vaccines found in database</span>);
if (vaccineStatsArr.length === 0) // no stats yet? show loading message
return (<span>Loading statistics...</span>);
return (<> // tip: React.Fragment shorthand
{
vaccineStatsArr.map(([name, stats]) => {
// this is an example component, find something suitable
// the `key` property is required
return (<BarGraph
key={name}
title={`${name} Statistics`}
columns={["One Dose", "Two Doses"]}
data={[stats.withOneDose, stats.withTwoDoses]}
/>);
});
}
</>);
};
export default Vaccine;
Live Statistics
If you want your graphs to be updated live, you need "zip together" the two snapshot listeners into one, similar to the rxjs combineLatest operator. Here is an example implementation of this:
const onVaccineStatsSnapshot => (vaccine, observerOrSnapshotCallback, errorCallback = undefined) => {
const observer = typeof observerOrCallback === 'function'
? { next: observerOrSnapshotCallback, error: errorCallback }
: observerOrSnapshotCallback;
let latestWithOneDose,
latestWithTwoDoses,
oneDoseReady = false,
twoDosesReady = false;
const fireNext = () => {
// don't actually fire event until both counts have come in
if (oneDoseReady && twoDosesReady) {
observer.next({
withOneDose: latestWithOneDose,
withTwoDoses: latestWithTwoDoses
});
}
};
const fireError = observer.error || (err) => console.error(err);
const oneDoseUnsubscribe = baseQuery
.where("doses.dose1", "==", true)
.where("doses.dose2", "==", false)
.onSnapshot({
next: (querySnapshot) => {
latestWithOneDose = querySnapshot.size;
oneDoseReady = true;
fireNext();
},
error: fireError
});
const twoDoseUnsubscribe = baseQuery
.where("doses.dose1", "==", true)
.where("doses.dose2", "==", true)
.onSnapshot({
next: (querySnapshot) => {
latestWithTwoDoses = querySnapshot.size;
twoDosesReady = true;
fireNext();
},
error: fireError
});
return () => {
oneDoseUnsubscribe();
twoDoseUnsubscribe();
};
}
You could rewrite the above function to make use of useState, but this would unnecessarily cause components to rerender when they don't need to.
Usage (direct):
const unsubscribe = onVaccineStatsSnapshot(vaccineName, {
next: (statsSnapshot) => {
// do something with { withOneDose, withTwoDoses } object
},
error: (err) => {
// TODO: error handling
}
);
or
const unsubscribe = onVaccineStatsSnapshot(vaccineName, (statsSnapshot) => {
// do something with { withOneDose, withTwoDoses } object
});
Usage (as a component):
const VaccineStatsGraph = (vaccineName) => {
const [stats, setStats] = useState(null);
useEffect(() => onVaccineStatsSnapshot(vaccineName, {
next: (newStats) => setStats(newStats),
error: (err) => {
// TODO: Handle errors
}
}, [vaccineName]);
if (!stats)
return (<span>Loading graph for {vaccineName}...</span>);
return (
<BarGraph
title={`${name} Statistics`}
columns={["One Dose", "Two Doses"]}
data={[stats.withOneDose, stats.withTwoDoses]}
/>
);
}
vaccines is an array and not a function. You are trying to run a map on vaccines. Try refactoring your code to this:
vaccines &&
vaccines.map((v, index) => {
// ...
})
Also do check: How to call an async function inside a UseEffect() in React?
here is the code, that works for you:
function DatafromFB() {
const[users, setUsers] = useState({});
useEffect(()=>{
const fetchVaccine = async () => {
try {
const docs = await db.collection("vaccines").get();;
docs.forEach((doc) => {
doc.data().vaccineDetails
.forEach(vaccineData=>{
fetchUsers(vaccineData.vaccine)
})
})
} catch (error) {
console.log("error", error);
}
}
const fetchUsers = async (vaccine)=>{
try {
const docs = await db.collection("users")
.where("doses.selectedVaccine", "==", vaccine).get();
docs.forEach(doc=>{
console.log(doc.data())
setUsers(doc.data());
})
}catch(error){
console.log("error", error);
}
}
fetchVaccine();
},[])
return (
<div>
<h1>{users?.doses?.selectedVaccine}</h1>
</div>
)
}
export default DatafromFB
what is ${index.vaccine} I think it must be v.vaccine
also setSize(snap.size); will set set size commonly not vaccine specific
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'.