Develop Reference

Firebase Query and how to read the output

Above is my Js code
I have a database that has information regarding the location of an apartment, I am trying to search for a specific property to see if it exists in the database. The user will be able to key into the search box to perform the search.
"propertiesRef" is used to store the user input.
I tried storing the data into "q" that I received from querying the database. But I have no idea how to read the result.
This is the console log for "q", but I don't quite understand the information that is shown, I want to know which output in the console should I be looking at and how do I access them?

The query() function just creates an instance Query. You need to use getDocs() function to actually fetch data from Firestore.
const search = (property) => {
const propertiesRef = collection(db, "flats-table");
const q = query(propertiesRef, where("name", "==", property))
return getDocs(q).then((qSnap) => {
const data = qSnap.docs.map(d => ({ id: d.id, ...d.data() }))
console.log(data);
return data;
})
// or use async-await
// const qSnap = await getDocs(q);
}
Checkout the documentation for more examples.

A firestore query not working in react-native

I am using react-native and I want to get specific data so I used a query, the problem is that it didn't work, but if I remove the where and do an if statement it works. How can I fix this ?
This is my implementation:
let query = firestore().collection('conversations');
query = query.where('users', 'array-contains', myId);
// query = query.where('postId', '==', postId);
query
.orderBy('timestamp', 'desc')
.limit(limit)
.get()
.then((snapshot) => {
const offersObjects = {};
if (snapshot.docs.length) {
snapshot.docs.forEach((doc) => {
if (postId === doc.data().postId) {
offersObjects[doc.id] = { ...doc.data(), pendingMessages: [] };
}
});
dispatch({
type: chatTypes.SET_OFFERS,
payload: { offers: offersObjects },
});
}
})
Where the code is commented is where this query doesn't work which is weird since the one above it works fine. How can I fix this ?

If you have more than one condition on a query, it may need a composite index that is not automatically created. If that is the case, executing the query (e.g. by calling get() on it) will raise an error, but you'r not hancling errors. I recommend adding a catch clause after your then and logging the error.
If the problem is caused by a missing index, the error message contains a URL that opens the Firebase console on the page to create the exact index that is needed, with all fields already filled in. Create the index, wait for it to be completely created, and run the query again.

need help accessing Firestore sub-collection?

I'm a novice when it comes to coding (started teaching myself ~year ago), any help will be much appreciated, thank you in advance.
I saw that there is 3-4 other post on stack overflow on how to access Firestore's sub-collections.
I tried them all and had no luck, hence why I'm posting this as a new question.
right now I have my data set is up as: collection/document.array. And that was fine till now because I just needed to read that data from the array to draw it out in my little React project with .reduce and .map and push new data to that array on input.
this is the code I have right now for getting data from Firestore:
--- in firebase.js ----------------------------------------------------------------------
export const fire = firebase.initializeApp(config);
export const db = fire.firestore()
_________________________________________________________________________________________
--- in events-context.js ----------------------------------------------------------------
const fetchEvents = async () => {
try {
const data = await db.collection('events').get();
setEvents(data.docs.map(doc => ({ ...doc.data(), id: doc.id })));
} catch ({ message }) {
alert(`Error # fetchEvents, Error:${message}`);
}
};
But now I want to add edit and a remove feature, but in order to do that, I need to carry out my array of data into a sub-collection so each individual element from that array had its own id so that I could later target it. so it needs to be set up something like this: collection/document/sub-collection

To access a document inside a collection, you must know the document ID from another source. This can be done by managing the names inside an array of strings or maps that you can then process within your app per your design.
For example: once created, you will have a snapshot of the reference of which you can store the document id inside the parent document:
db.collection("events").doc(id).update({
payers: firebase.firestore.FieldValue.arrayUnion(paySnapshot.ref.id)
})`
Once you have this information, you can append it to the relevant document path using one of the following techniques.
db.collection("events").doc(id).collection("payers").doc(pay_id).get()
db.doc(\events/${id}/payers/${pay_id}`).get()`
I strongly advise against using .get() on a collection without limit() and where() conditions to reduce the reads that can occur.

Try this, it works for me :)
Insert data >>>
const q = query(collection(this.fire, "events"));
const querySnapshot = await getDocs(q);
const queryData = querySnapshot.docs.map((details) => ({
...details.data(),
id: details.id,
}));
console.log(queryData);
queryData.map(async (v, id) => {
await setDoc(doc(this.fire, `events/${auth}/more`, events.title), {
'title': events.title,
'uid': auth,
//your data here
})
})
Read Data >>>
const querySnapshot = await getDocs(collection(this.fire,
`/events/${auth}/more/`)); querySnapshot.forEach((doc) => { //
doc.data() is never undefined for query doc snapshots
console.log(doc.id, " => ", doc.data()); });
return querySnapshot;

firebase.firestore() shows bizarre data and not my actual documents from the database/

I am querying firebase firestore by...
let database = firebase.firestore();
let places = database.collection("place");
console.log("places", places);
now the logged data is bizarre and not the actual documents..
here is a picture of the log...can you please advice regarding tackling this ?

If you want to retrieve all items in your collections called "place" you can do something like this:
let database = firebase.firestore();
let places = database.collection("place");
const querySnapshot = places.get()
// You can make an empty array to eventually push the items into
const collectionArray = []
querySnapshot.forEach((doc) => {
const data = doc.data()
collectionArray.push(data)
}).catch(function(error) {
console.log("Error getting documents: ", error);
})
console.log('collectionArray:',collectionArray)
}

Your code hasn't actually executed any query yet. All it's done is build a Query object.
If you want to execute the query, call get() on it, and handle the results as shown in the documentation.
let database = firebase.firestore();
let query = database.collection("place");
query.get()
.then(querySnapshot => {
querySnapshot.forEach(documentSnapshot => {
console.log("document", documentSnapshot.data());
})
})

Receiving undefined when retrieving value from firebase

Where is my call wrong? The first console.log leads to the role object and the second console.log leads to undefined. When it should be the user.
componentDidMount(){
let user = fire.auth().currentUser;
let db = fire.database();
let roleRef = db.ref('/roles');
roleRef.orderByChild('user').equalTo(user.uid).once('value', (snapshot) => {
console.log(snapshot.val())
console.log(snapshot.val().user);
})
}
Result:
Firebase:

When you execute a query against the Firebase Database, there will potentially be multiple results. So the snapshot contains a list of those results. Even if there is only a single result, the snapshot will contain a list of one result.
Your code doesn't take the list into account. The easiest way to do so is with Snapshot.forEach():
roleRef.orderByChild('user').equalTo(user.uid).once('value', (snapshot) => {
snapshof.forEach((roleSnapshot) => {
console.log(roleSnapshot.val())
console.log(roleSnapshot.val().user);
});
})