I am working with a project where we create a bunch of entries in firestore based on results from an API endpoint we do not control, using a firestore cloud function. The API endpoint returns ids which we use for the document ids, but it does not include any timestamp information. Since we want to include a createdDate in our documents, we are using admin.firestore.Timestamp.now() to set the timestamp of the document.
On subsequent runs of the function, some of the documents will already exist so if we use batch.commit with create, it will fail since some of the documents exist. However, if we use batch.commit with update, we will either not be able to include a timestamp, or the current timestamp will be overwritten. As a final requirement, we do update these documents from a web application and set some properties like a state, so we can't limit the permissions on the documents to disallow update completely.
What would be the best way to achieve this?
I am currently using .create and have removed the batch, but I feel like this is less performant, and I occasionally do get the error Error: 4 DEADLINE_EXCEEDED on the firestore function.
First prize would be a batch that can create or update the documents, but does not edit the createdDate field. I'm also hoping to avoid reading the documents first to save a read, but I'd be happy to add it in if it's the best solution.
Thanks!
Current code is something like this:
const createDocPromise = docRef
.create(newDoc)
.then(() => {
// success, do nothing
})
.catch(err => {
if (
err.details &&
err.details.includes('Document already exists')
) {
// doc already exists, ignore error
} else {
console.error(`Error creating doc`, err);
}
});
This might not be possible with batched writes as set() will overwrite the existing document, update() will update the timestamp and create() will throw an error as you've mentioned. One workaround would be to use create() for each document with Promise.allSettled() that won't run catch() if any of the promise fails.
const results = [] // results from the API
const promises = results.map((r) => db.doc(`col/${r.id}`).create(r));
const newDocs = await Promise.allSettled(promises)
// either "fulfilled" or "rejected"
newDocs.forEach((result) => console.log(result.status))
If any documents exists already, create() will throw an error and status for that should be rejected. This way you won't have to read the document at first place.
Alternatively, you could store all the IDs in a single document or RTDB and filter out duplicates (this should only cost 1 read per invocation) and then add the data.
Since you prefer to keep the batch and you want to avoid reading the documents, a possible solution would be to store the timestamps in a field of type Array. So, you don't overwrite the createdDate field but save all the values corresponding to the different writes.
This way, when you read one of the documents you sort this array and take the oldest value: it is the very first timestamp that was saved and corresponds to the document creation.
This way you don't need any extra writes or extra reads.
Related
Hoi, I would like to check, using React javascript, if a collection in the Firestore already exists, no matter if it's empty or not. I tried:
if (collection(db, ref)) // is always true somehow
Any ideas? Thanks!
You would need to try to fetch from the collection and see if anything is returned:
const snap = await query(collection(db, ref), limit(1));
if (snap.empty) {
// no docs in collection
}
There is no function available in the SDK that can help you can check if a particular collection exists. A collection will start to exist only if it contains at least one document. If a collection doesn't contain any documents, then that collection doesn't exist at all. So that being said, it makes sense to check whether a collection contains or not documents. In code, it should look as simple as:
const snapshot = await query(collection(db, yourRef), limit(1));
if (snapshot.empty) {
//The collection doesn't exist.
}
One thing to mention is that I have used a call to limit(1) because if the collection contains documents, then we limit the results so we can pay only one document read. However, if the collection doesn't exist, there is still one document read that has to be paid. So if the above query yields no resul## Heading ##t, according to the official documentation regarding Firestore pricing, it said that:
Minimum charge for queries
There is a minimum charge of one document read for each query that you perform, even if the query returns no results.
You have to fetch the collection out of the database and check if it has more than 0 documents. Even, if the collection doesn't exist, it will return 0.
const db = firebase.firestore();
db.collection("YOUR COLLECTION NAME").get().then((res) =>{
if(res.size==0){
//Collection does not exist
}else{
//Collection does exist
}
I have a collection
/userFeed
Where I create/delete docs (representing users) when the current user starts following/unfollowing them.
...
/userFeed (C)
/some-followed-user (D)
-date <timestamp>
-interactions <number>
When the user likes a post, the interactions field will be updated. But... what if the user doesn't follow the post owner? Then, I will just need to skip the document update, without necessity of producing failures/errors.
const currentUserFeedRef = firestore
.collection("feeds")
.doc(currentUserId)
.collection("userFeed")
.doc(otherUserId);
const data = {
totalInteractions: admin.firestore.FieldValue.increment(value),
};
const precondition = {
exists: false, // I am trying weird things
};
if (batchOrTransaction) {
return batchOrTransaction.update(
currentUserFeedRef,
data,
precondition
);
}
Is it possible to just "skip the update if the doc doesn't exist"?
Is it possible to just "skip the update if the doc doesn't exist"?
No, not in the way that you're explaining it. Firestore updates don't silently fail.
If you need to know if a document exists before updating it, you should simply read it first and check that it exists. You can do this very easily in a transaction, and you can be sure that the update won't fail due to the document being missing if you check it this way first using the transaction object.
In fact, what you are trying to do is illustrated as the very first example in the documentation.
I was wondering how I can query documents from a firestore collection from an array of ID's? I only want the documents in the collection that are in the array of ID's. I looked at another answer and think my approach is correct, however, I am getting an error.
(node:15105) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'data' of undefined
> at /Users/username/SideProjects/projectname/functions/index.js:40:38
> at processTicksAndRejections (internal/process/task_queues.js:95:5)
The error happens because the function is not finding any documents in the collection from that array of ID's. However, I double-checked the database and know that there are documents in the collection with ID's from the array.
const admin = require('firebase-admin')
....
let feedItems = db.collection(feedItemsCollection)
feedItemsList = feedItems.where(admin.firestore.FieldPath.documentId(), 'in', ['HPOorsSnbHpTYwwXxfWw']).get().then(snapshot2 => {
console.log(admin.firestore.FieldPath.documentId())
console.log("In feed Items")
//console.log(feedItemIds)
console.log(snapshot2[0])
//error happens on this line because snapshot2[0] returns undefined
console.log(snapshot2[0].data())
})
Snapshot2[0] returns undefined which I'm assuming means that no data was returned. I think I'm not properly calling documentId(), but don't know the fix.
There "maybe" two problems with your code. Follow both points to make sure things are working
Data inside snapshot2 maybe empty
You'll first have to fix your code to test this theory. You're not accessing data from snapshot2 correctly. To do it right, one way is this:
// `snapshot2` will have a `docs` property that you can leverage
const snapshot2Data = snapshot2.docs.map((doc) => doc.data());
.documentId() may not be doing what it's supposed to (as you said)
To test this theory, check if snapshot2Data is empty. Run :
console.log(snapshot2Data); // what do you get ?
If no, it's not empty and you got data back, then you're all set. Nothing more to do
If yes, it is empty, then run :
console.log(admin.firestore.FieldPath.documentId()); // what do you get ?
Did you get back a string? If no, then we have another problem. You'll need to take a closer look at your firebase-admin setup, as well.
I'm trying to retrieve a single document from a collection. I'm now using the code below that returns a collections of items, but I know that there is only one item. So it ain't that clean.
Setup:
private db: AngularFirestore
private itemSubs: Subscription[] = [];
itemAd= new Subject<Item>();
fetchItemFromDatabase(itemId: string) {
this.itemSubs.push(
this.db.collection('items', id => id.where('itemId', '==', itemId)).valueChanges().subscribe((items: Item[]) => {
this.itemAd.next(items);
}));
}
I tried to do it with this.db.collection('items').doc(itemId).get() , but I'm getting an error on get() that it's not found/supported. I also didn't got autocompletion when trying to call this methode (methode found in the official cloud firestore documents).
I looked at around at some other solutions and then tried it with this.db.collection('items').doc(itemId).ref.get().then(...) , but here I got an empty doc back.
So I'm a bit stuck at the moment and I don't want to use that whole collections logic when I know there is only 1 item in it.
There may be multiple documents with itemId equal to a given value. While you may know that there is only one in your app, the database and API cannot know nor enforce that. For that reason the query you run will always return a query snapshot that potentially contains multiple documents.
this.db.collection('items', id => id.where('itemId', '==', itemId))
If you want to enforce that there is only one document with the given item ID, consider using that item ID as the document name instead of storing it as a field in the document.
There can be only one document with a given name, so that means the ID is guaranteed to be unique. And you can then retrieve that document with:
this.db.collection('items').doc(itemId)
I'm working on Meteor, trying to find some values from Mongodb collection.
here is the code:
var sameLogins = Users.findOne({login: 'a'});
console.log(sameLogins);
But it's returning and "undefined".
But record exists in collection:
So, can anybody tell what I'm missing?
Also, in mongo console - everything is working fine:
I was looking in Publish/Subsribe stuff, but i'm using autopublish module yet.
Thank you!
I will leave the answer for this issue for new users having the same problem.
If you're using autopublish package then you should be aware that it's publishing the result of .find() for every collection.
But, Meteor.users.find(), be default, will return only _id and profile fields, so documents in your Meteor.users client collection will have these two fields only.
The most easy workaround for this would be to create your own publication (allUsers, for example) and in it to return those fields you need:
Server:
Meteor.publish('allUsers', () => {
// check for Meteor.userId() is omitted, put it here, if needed
return Meteor.users.find({}, { fields: { ... } });
});
Don't forget to subscribe to it:
Client:
Meteor.subscribe('allUsers');
Update for Meteor:
Right now you are storing a cursor in your variable sameLogins. In order to retrieve the results you want, you must actually execute this query by either calling fetch(). What is returned from findOne without fetch is essentially an object that you could use to iterate over and find mongoDB documents - (called a collection cursor). The cursor is not your result itself.
Calling fetch would like something like:
Users.findOne({login: 'a'}).fetch()