Develop Reference

i cannot access the value inside a function

Here is my code :
let namesList = ref([]);
const GetFormData = (payload) => {
return new Promise((resolve, reject) => {
api
.get("api.php", { params: { search: payload } })
.then((response) => {
data.value = response.data;
// console.log(data.value);
// convert array objects to array strings
namesList = data.value.map(function (list) {
return list["first_name"];
});
// console.log(namesList);
})
.catch((error) => {
reject(error);
});
});
};
If I console the namelist inside the function it returns the value :
(9) ['Michael Angelodfsed', 'Mardin', 'Joemar', 'Chirs', 'chan', 'loys', 'Lorena', 'kayabusa', 'kayabusa']
0: "Michael Angelodfsed"
1: "Mardin"
2: "Joemar"
3: "Chirs"
4: "chan"
5: "loys"
6: "Lorena"
7: "kayabusa"
8: "kayabusa"
length: 9
[[Prototype]]: Array(0)
but if I console the variable outside the function it gives me this console.log(nameList);
RefImpl {__v_isShallow: false, dep: undefined, __v_isRef: true, _rawValue: Array(0), _value: Proxy}
dep: Set(1) {ReactiveEffect}
__v_isRef: true
__v_isShallow: false
_rawValue: []
_value: Proxy
[[Handler]]: Object
[[Target]]: Array(0)
[[IsRevoked]]: false
value: (...)
[[Prototype]]: Object
please help me guys. really struggling here. really appreciate your help.

Follow this:
consf nameList = ref([])
console.log(nameList.value) // get value
nameList.value = ["Shin"] // set value

As #Deepak stated, you are trying to access the variable before the function (the api call) ends.
Your namesList is a ref object, so when you log it before it ends, it logs the object.
As your function is calling an api and use a Promise, you can change your function code to this:
const GetFormData = (payload) => {
return new Promise((resolve, reject) => {
api
.get("api.php", { params: { search: payload } })
.then((response) => {
data.value = response.data;
// console.log(data.value);
// convert array objects to array strings
namesList = data.value.map(function (list) {
return list["first_name"];
});
// console.log(namesList);
resolve(namesList);
})
.catch((error) => {
reject(error);
});
});
};
GetFormData(payload).then(data => console.log(data))

It is not possible to make a loop through the array

There is a request to Firebase, using then I add new elements to the array. If you output console.log, then there are elements, but lenght = 0 and loops do not work.
export const useLastMessageDialogs = (messagesStatus: StatusDialogType): UserMessageType[] => {
const messages: string[] = [];
useEffect(() => {
const querySideDialogs = query(
collection(firestoreDb, 'questions'),
where('status', '==', messagesStatus)
);
onSnapshot(querySideDialogs, (dialogs) => {
dialogs.docChanges().forEach((dialog) => {
getDocs(
query(
collection(firestoreDb, 'questions', dialog.doc.id, 'messages'),
orderBy('timestamp', 'desc'),
limit(1)
)
).then((response) => {
response.forEach((message) => {
messages.push('bebebe');
});
});
});
});
}, [messagesStatus]);
console.log(messages); // [0: "bebebe", 1: "bebebe" length: 2]
console.log(messages.length); // 0
return [];
};

I took it to a separate service and connected it via redux-saga

Compare two arrays in react and filter one based on matches of name property

I'm trying to filter a players array by comparing the names property to a roster array and rendering the matches from the players array.
When a user selects a year the getCollegeRoster() function returns players who have a year property matching the selection. From there I'm trying to filter and display the .name matches from the players array, but it seems i'm unable to update playerStateValue. I'm using recoil to manage state. Any insight would be much appreciated.
const getCollegeRoster = async () => {
setLoading(true);
try {
const playersQuery = query(
collection(firestore, `colleges/${communityData.id}/rosters`),
where("year", "==", selection),
);
const playerDocs = await getDocs(playersQuery);
const collegeRoster = playerDocs.docs.map((doc) => ({ id: doc.id, ...doc.data() }));
setRoster(collegeRoster as unknown as Roster[]);
console.log('collegePlayers', roster);
} catch (error: any) {
console.log("getCollegePlayers error", error.message);
}
setLoading(false);
};
const onSelection = (newSelection: any) => {
setSelection(newSelection);
console.log('newselect', newSelection)
getCollegeRoster();
const filteredArray = [...playerStateValue.players].filter((el) => ({
name: el.name,
match: [...roster].some((f) => f.name === el.name)
})
);
setPlayerStateValue((prev) => ({
...prev,
players: filteredArray as Player[],
playersCache: {
...prev.playersCache,
[communityData?.id!]: filteredArray as Player[],
},
playerUpdateRequired: false,
}));
} ```
also tried adding setplayerstatevalue into the getcollegeroster function:
onst getCollegeRoster = async () => {
console.log("WE ARE GETTING Players!!!");
console.log('communitydata', communityData);
setLoading(true);
try {
const playersQuery = query(
collection(firestore, `colleges/${communityData.id}/rosters`),
where("year", "==", selection),
);
const playerDocs = await getDocs(playersQuery);
const collegeRoster = playerDocs.docs.map((doc) => ({ id: doc.id, ...doc.data() }));
setRoster(collegeRoster as unknown as Roster[]);
console.log('collegePlayers', roster);
const filteredArray = [...playerStateValue.players].filter((el) => ({
name: el.name,
match: [...roster].some((f) => f.name === el.name)
})
);
setPlayerStateValue((prev) => ({
...prev,
players: filteredArray as Player[],
playersCache: {
...prev.playersCache,
[communityData?.id!]: filteredArray as Player[],
},
playerUpdateRequired: false,
}));
} catch (error: any) {
console.log("getCollegePlayers error", error.message);
}
setLoading(false);
};
{playerStateValue.players.map((player: Player, index) => (
<PlayerItem
key={player.id}
player={player}
// postIdx={index}
onPlayerVote={onPlayerVote}
userVoteValue={
playerStateValue.playerVotes.find((item) => item.playerId === player.id)
?.voteValue
}
onSelectPlayer={onSelectPlayer}
/>

I believe I found the problem. getCollegeRoster() is an async function which means it is being executed asynchronous.
That function is responsible for updating roster and you are using roster inside your filtering while it is being asynchronously updated.
There is no guarantee that roster is updated by the time you filter your array.
You have two ways of solving this. Either you execute setPlayerStateValue() inside of getCollegeRoster() or you wait for getCollegeRoster() to be done by preappending it with await and your onSelection function with async:
const onSelection = async (newSelection: any) => {
setSelection(newSelection);
console.log("newselect", newSelection);
await getCollegeRoster();
const filteredArray = [...playerStateValue.players].filter((el) => ({
name: el.name,
match: [...roster].some((f) => f.name === el.name),
}));
...
Edit:
Another scenario I can think of is that playerStateValue might be the culprit. In React setState works asynchronous as well, if you access playerStateValue via curr/prev-callback, it is guaranteed that you are accessing the values of the current state object while updating the state. Try this use of setPlayerStateValue:
setPlayerStateValue((prev) => {
const filteredArray = prev.players.filter((el) => ({
name: el.name,
match: [...roster].some((f) => f.name === el.name),
})) as Player[];
return {
...prev,
players: filteredArray,
playersCache: {
...prev.playersCache,
[communityData?.id!]: filteredArray,
},
playerUpdateRequired: false,
};
});

My array returned prints same objects multiple times, using await Promise.all with map()

When I print the length of the array it is 3, so basically arr[0], arr[1], arr[2] contain same objects, why is that so The array returned should be of length 1 containing all the objects.
const arr = await Promise.all(
ratingsArr.map(async (rating) => {
const pmRatingObj = {
rateeId: rating.employeeId,
createdAt: rating.createdAt,
updatedAt: rating.updatedAt,
rateeType: 'employee',
raterId: rating.projectManagerId,
freeze: rating.PMFreeze,
};
const pmRatingId = await queryInterface.bulkInsert('ratings', [pmRatingObj]);
// console.log(pmRatingId);
const archRatingObj = {
rateeId: rating.employeeId,
createdAt: rating.createdAt,
updatedAt: rating.updatedAt,
rateeType: 'employee',
raterId: rating.projectArchitectId,
freeze: rating.PMFreeze,
};
const archRatingId = await queryInterface.bulkInsert('ratings', [archRatingObj]);
const pmArr = await createPMAttributes(pmRatingId, rating);
pmArr.map((pm) => {
newArr.push(pm);
});
const archArr = await createArchAttributes(archRatingId, rating);
archArr.map((arch) => {
newArr.push(arch);
});
return newArr;
}),
);

Array.map() doesn't render anything in React

I'm trying to make a list in my react app. I have retrieved data from my database, and pushed it into a list. I have doublechecked that the data shows up correctly in the console, and it does, but array.map() returns nothing. I think the problem might be that array.map() runs two times. I don't know why it runs two times.
function Dashboard() {
const user = firebase.auth().currentUser;
const [teams, setTeams] = useState([])
const history = useHistory();
useEffect(() => {
getTeams()
if (user) {
} else {
history.push("/")
}
}, [])
function Welcome() {
if (user) {
return <h1>Welcome, {user.displayName}</h1>
} else {
}
}
const getTeams = () => {
firebase.firestore().collectionGroup('members').where('user', '==', user.uid).get().then((snapshot) => {
const docList = []
snapshot.forEach((doc) => {
docList.push({
teamId: doc.data().teamId,
})
})
const teamslist = []
docList.forEach((data) => {
firebase.firestore().collection('teams').doc(data.teamId).get().then((doc) => {
teamslist.push({
name: doc.data().name,
teamId: doc.id,
})
})
})
setTeams(teamslist)
})
}
const openTeam = (data) => {
console.log(data.teamId)
}
return (
<div>
<Welcome />
<div>
<ul>
{console.log(teams)}
{teams.map((data) => {
return (
<li onClick={() => openTeam(data)} key={data.teamId}>
<h1>{data.name}</h1>
<p>{data.teamId}</p>
</li>
)
})}
</ul>
</div>
</div>
)
}
export default Dashboard

The getTeams function has a bug where it isn't waiting for the firebase.firestore().collection('teams').doc(data.teamId).get().then promises to finish before calling setTeams, so it is called with an empty array, causing React to trigger a render with the empty array.
As the promises for fetching each team resolve they will be pushed to the same array reference, but this won't trigger a rerender in React since you're not calling setTeams again when the array changes.
Try this code, which won't call setTeams until each team promise generated from docList has been resolved.
const getTeams = () => {
firebase.firestore().collectionGroup('members').where('user', '==', user.uid).get().then((snapshot) => {
const docList = []
snapshot.forEach((doc) => {
docList.push({
teamId: doc.data().teamId,
})
})
const teamslist = [];
Promise.all(docList.map((data) => {
return firebase
.firestore()
.collection('teams')
.doc(data.teamId)
.get()
.then((doc) => {
teamslist.push({
name: doc.data().name,
teamId: doc.id,
})
})
}))
.then(() => setTeams(teamslist));
})
}
A smaller edit would be to call setTeams after each separate team promise resolves, which will trigger a React render each time a new team is resolved:
.then((doc) => {
teamslist.push({
name: doc.data().name,
teamId: doc.id,
});
// create a new array, since using the same array
// reference won't cause react to rerender
setTeams([...teamslist]);
})

Many thanks to #martinstark who provided you an answer while I was unavailable.
However, there are some more things that need to be covered.
User State
In your current component, you pull the current user from Firebase Authentication, but don't handle the state changes of that user - signing in, signing out, switching user. If a user is signed in and they were to navigate directly to your dashboard, firebase.auth().currentUser could be momentarily null while it resolves the user's login state, which would incorrectly send them off to your login page.
This can be added using:
const [user, setUser] = useState(() => firebase.auth().currentUser || undefined);
const userLoading = user === undefined;
useEffect(() => firebase.auth().onAuthStateChanged(setUser), []);
Next, in your first useEffect call, you call getTeams() whether the user is signed in or not - but it should depend on the current user.
useEffect(() => {
if (userLoading) {
return; // do nothing (yet)
} else if (user === null) {
history.push("/");
return;
}
getTeams()
.catch(setError);
}, [user]);
// This getTeams() is a () => Promise<void>
const getTeams = async () => {
const membersQuerySnapshot = await firebase.firestore()
.collectionGroup('members')
.where('user', '==', user.uid)
.get();
const docList = []
membersQuerySnapshot.forEach((doc) => {
docList.push({
teamId: doc.get("teamId"), // better perfomance than `doc.data().teamId`
});
});
const teamDataList = [];
await Promise.all(docList.map((data) => {
return firebase.firestore()
.collection('teams')
.doc(data.teamId)
.get()
.then(doc => teamDataList.push({
name: doc.get("name"),
teamId: doc.id
}));
}));
setTeams(teamDataList);
}
Optimizing getTeams() - Network Calls
The getTeams function in your question calls setTeams with the array [], which will be empty at the time of calling it as covered in #martinstark's answer. The "get team data" operations are asyncronous and you aren't waiting for them to resolve before updating your state and triggering a new render. While you are pushing data to them after the component has rendered, modifying the array won't trigger a new render.
While you could fetch the data for each team using db.collection("teams").doc(teamId).get(), each of these is requests is a network call, and you can only make a limited number of these in parallel. So instead of fetching 1 team per network call, you could fetch up to 10 teams per network call instead using the in operator and FieldPath.documentId().
Assuming the collectionGroup("members") targets the collections of documents at /teams/{aTeamId}/members which contain (at least):
"/teams/{aTeamId}/members/{memberUserId}": {
teamId: aTeamId,
user: memberUserId, // if storing an ID here, call it "uid" or "userId" instead
/* ... */
}
// this utility function lives outside of your component near the top/bottom of the file
function chunkArr(arr, n) {
if (n <= 0) throw new Error("n must be greater than 0");
return Array
.from({length: Math.ceil(arr.length/n)})
.map((_, i) => arr.slice(n*i, n*(i+1)))
}
// This getTeams() is a () => Promise<void>
const getTeams = async () => {
const membersQuerySnapshot = await firebase.firestore()
.collectionGroup('members')
.where('user', '==', user.uid)
.get();
const teamIDList = []
membersQuerySnapshot.forEach((doc) => {
teamIDList.push(doc.get("teamId")); // better perfomance than `doc.data().teamId`
})
const chunkedTeamIDList = chunkArr(teamIDList, 10) // split into batches of 10
const teamsColRef = firebase.firestore().collection('teams');
const documentId = firebase.firestore.FieldPath.documentId(); // used with where() to target the document's ID
const foundTeamDocList = await Promise
.all(chunkedTeamIDList.map((chunkOfTeamIDs) => {
// fetch each batch of IDs
return teamsColRef
.where(documentId, 'in', chunkOfTeamIDs)
.get();
}))
.then((arrayOfQuerySnapshots) => {
// flatten results into a single array
const allDocsList = [];
arrayOfQuerySnapshots.forEach(qs => allDocsList.push(...qs.docs));
return allDocsList;
});
const teamDataList = foundTeamDocList
.map((doc) => ({ name: doc.get("name"), teamId: doc.id }));
// sort by name, then by ID
teamDataList.sort((aTeam, bTeam) =>
aTeam.name.localeCompare(bTeam.name) || aTeam.teamId.localeCompare(bTeam.teamId)
)
// update state & trigger render
setTeams(teamDataList);
}
You can also make use of this utility function to simplify & optimize the code a bit. Which gives:
// This getTeams() is a () => Promise<void>
const getTeams = async () => {
const membersQuerySnapshot = await firebase.firestore()
.collectionGroup('members')
.where('user', '==', user.uid)
.get();
const teamIDList = []
membersQuerySnapshot.forEach((doc) => {
teamIDList.push(doc.get("teamId")); // better perfomance than `doc.data().teamId`
})
const teamsColRef = firebase.firestore().collection('teams');
const teamDataList = [];
await fetchDocumentsWithId(
teamsColRef,
teamIDList,
(doc) => teamDataList.push({ name: doc.get("name"), teamId: doc.id })
);
// sort by name, then by ID
teamDataList.sort((aTeam, bTeam) =>
aTeam.name.localeCompare(bTeam.name) || aTeam.teamId.localeCompare(bTeam.teamId)
)
// update state & trigger render
setTeams(teamDataList);
}
Optimizing getTeams() - Function Definition
As part of the last optimization, you could pull it out of your component or place it in its own file so that it's not redefined with every render:
// define at top/bottom of the file outside your component
// This getTeams() is a (userId: string) => Promise<{ name: string, teamId: string}[]>
async function getTeams(userId) => {
const membersQuerySnapshot = await firebase.firestore()
.collectionGroup('members')
.where('user', '==', userId)
.get();
const teamIDList = []
membersQuerySnapshot.forEach((doc) => {
teamIDList.push(doc.get("teamId")); // better perfomance than `doc.data().teamId`
})
const teamsColRef = firebase.firestore().collection('teams');
const teamDataList = [];
await fetchDocumentsWithId(
teamsColRef,
teamIDList,
(doc) => teamDataList.push({ name: doc.get("name"), teamId: doc.id })
);
// sort by name, then by ID
teamDataList.sort((aTeam, bTeam) =>
aTeam.name.localeCompare(bTeam.name) || aTeam.teamId.localeCompare(bTeam.teamId)
)
// return the sorted teams
return teamDataList
}
and update how you use it:
useEffect(() => {
if (userLoading) {
return; // do nothing
} else if (user === null) {
history.push("/");
return;
}
getTeams(user.uid)
.then(setTeams)
.catch(setError);
}, [user]);