I'm trying to get the real-time document fields (text and timeStamp) to be displayed from the "first" collection in firestore collection, with the use of onSnapshot. I can verify that the snapshot realtime updation is working, on addition of a new document, it does shows an update. But I cannot access the text and timeStamp in the document.
onSnapshot(collection(db, 'first'), (snapshot) => {
console.log(snapshot.text, snapshot.timeStamp);
});
It just shows undefined to me. Also, I just want to access this database, db only when the user is authenticated. So is there a way to check if the user is authenticated?
To get the data from a document snapshot, you need to call data() on it. In addition, since you're reading an entire collection, you get back a query snapshot that can contain multiple documents, which you also need to handle.
So:
onSnapshot(collection(db, 'first'), (querySnapshot) => {
querySnapshot.docs.forEach((docSnapshot) => {
console.log(docSnapshot.data().text, docSnapshot.data().timeStamp);
})
});
See the documentation on getting data from Firestore and on reading all documents from a collection for more examples like this.
Related
I am configuring my Vue/Firebase chat app to save the email address of a registered user in a Firestore collection when the registered user is logged in and submits a message. The Firestore Database looks like the following, with the users added to the "user" collection, and with each user containing a "message" collection:
In my code, I am attempting to add a function that returns the email addresses listed in the "users" collection, as seen in the screenshot:
const contactList = ref([])
const getContacts = () => {
firebase.firestore().collection("users").onSnapshot(snap => {
contactList.value = []
snap.forEach(doc => {
const users = doc.data();
users.id = doc.id;
contactList.value.push(users)
console.log(users)
})
})
},
However, this function does not simply return those email addresses in the user collection, since .collection('users') is the first collection in a chain of docs and collections as indicated in the screenshot. How can I go about returning the list of users in the "users" collection when .collection('users') is the first in a chain of docs and collections?
The document titles are shown in italic, meaning that there are actually no documents with that ID (also shown in the bottom) right and the console merely shows them in order to be able to show the subcollections.
The API won't return such non-existing documents. You'll have to create the document to be able to then read them, for example by running a collection group query over all messages collections and checking if their parent document exists already.
Also see:
Why are non auto-generated document Ids are in italics in Firestore console?
Firestore DB - documents shown in italics
Setting document via subpaths in firebase causes them to show up as italic?
Firestore document/subcollection is not existing
This is the thing I want to accomplish: I'm building a web shop. The web shop has a React Front-end. The front-end fetches 5 collections from Firestore and displays all the items from the collection array on the shop page. A user selects an item on the shop page. I send the item fields such as (price, name, quantity, id) to my express server and the server makes a checkout session of the item fields. The user goes to a Stripe checkout form and is sent back to my front-end by Stripe when the payment is complete. I listen for that event on my server and when then want to update the quantity field of the item in Firestore.
But how do I query Firestore for this item? Is there a way to query Firestore with only this id field (or name field)? Some something like:
db
.collection('collections')
.where('id', '===', 1)
Or do I need to save the document id (of the collection) as a field inside the item map and also send that to Stripe? Or is there a better way to do this? I can't find anything online about this.
Here is a screenshot of Firestore.
Please forgive my beginner question. I'm still learning React, Firestore and Node.js.
First be sure you are sticking to the Firestore terminology correctly. There are collections and there are documents.
Collections you access via a path such as:
collRef = db.collection("products")
collRef = db.collection("products").where("quanity_on_hand", ">", "0")
collRef = db.collection("products").doc("12345").collection("purchase_history")
The latter instance can also be accessed via collRef = db.collection("products/12345/purchase_history").
In all the above cases you will get back a CollectionReference.
Documents you access such as:
docRef = db.collection("products").doc("12345")
docRef = db.doc("products/12345")
This returns you a DocumentReference for the document whose ID is "12345" in the collection "products".
So for your code example above, you want to use docRef = db.doc("collections/1") to get back the DocumentReference for the item you are after. (Or, alternatively, you could use: docRef = db.collection("collections").doc("1")
If you stick with the code that you have above, you'd get back a CollectionReference then you'd need to fetch the data with .get(), then extract the resulting documents (that will just be a single document), then work with that. Oh...and you will need to put an "id" field into all of your documents because the document's ID value (the "name" of the document) is not part of the document by default so if you want to use .where("id", "==", "1"), then you need to add an "id" field to your document and populate it correctly.
If you go with docRef = db.doc("collections/1"), you are querying for the document directly and will get back a reference to just that one. No need for extra fields, nor extracting a single document from a result set.
I currently have the following node:
Basically what I want is to search the registry by the uid parameter. What I can not understand is that they tell me that I should not do it by means of a query, so what would be the other way? I have tried with the following:
firebase
.database()
.ref('nuevosUsuario')
.child(user.uid)
.once('value')
.then(snapshot =>
console.log(snapshot.val())
);
pero me imprime en consola null
Thank you in advance, I'm new to firebase.
You JSON structure stores user information, where it stores the information for each user under a so-called push ID (a key generated by calling push() or childByAutoId()). You're trying to query this structure to find the user based on their UID, which is stored in a property for each user. The only way to do this is by using a database query, like:
firebase.database()
.ref('nuevosUsuario')
.orderByChild("uid")
.child(user.uid)
.once('value')
.then(snapshot => {
snapshot.forEach(userSnapshot => {
console.log(snapshot.val())
});
});
You need to perform a loop here, since there may be multiple nodes that have the correct value for their UID property.
If there can logically be only one node for each user under nuevosUsuario, it is better to store the user information under the user's UID as a key, instead of using a push ID.
So you'd get a structure like:
"nuevosUsuario": {
"SYFW1u808weaGEf3fW...": {
"appellido": "PRUEBA",
"correo": "..."
...
}
}
This has a few advantages:
There can only be one child node for each user, since keys are by definition unique in a collection.
You can now get the user given their UID without a query, which is both faster and simpler in code. As in: the code in your question would work for this structure.
I have the following query:
get invitations() {
return this.firestore.colWithIds$(`users/${this.authProvider.currentUserId}/meetings`, (ref) => {
return ref
.where(`participants.${this.authProvider.currentUserId}.invitation`, '==', 'pending')
.orderBy('createdAt', 'desc')
});
}
Everytime Firebase will generate an error that says: This query required an index and generates a link with the currentUserId in it. I add it to the console and everything works as expected..
However, this seems a bit too manual to maintain when users are registering. How can I generate a index that is dynamic and does not require manual entry every time a new user downloads my app?
The query you want to do, in the general case, is not possible in Cloud Firestore with your data structure.
You will quickly run into the limit of 200 composite indexes per database, probably around your 200th user:
https://firebase.google.com/docs/firestore/quotas#indexes
I have been reading a little about how to structure your firebase database and i understand that you need to split your data into pieces so you don't forced the client to download all of the 'users' data.
So in this example you will get all the users data when you write
ref.('users').once('value', function(snap)...
/users/uid
/users/uid/email
/users/uid/messages
/users/uid/widgets
but what if you specifically write the path to the location instead like
ref.('users/uid/email').once('value', function(snap)...
Will you still get all the users data or only the data in email ?
In firebase, you set the ref to be the reference for your database (the whole database) and then you got methods to iterate through each piece of data of your database object, hence, a good practice is to set all your database as the ref and then work from there to go through what you want to go.
// will select the whole db
const firebaseRef = firebase.database().ref();
// will select the whole app object of your db
const firebaseRef = firebase.database().ref().child('app');
// will select the whole users object of your db
const firebaseRef = firebase.database().ref().child('app/users');
So, it is a good practice to set a variable like firebaseRef to be your whole firebase db and then iterate from there.
Now, if you write:
firebaseRef.child(`users/${uid}/email`).once('value').then(snapshot => {
console.log('User email: ', snapshot.val());
}, e => {
console.log('Unable to fetch value');
});
Yes, you will get what you're asking, but you need to use the child method to get to the objects of your firebase ref.