How to get the number of Firestore documents in flutter

Question

I am building a flutter app and using Cloud Firestore. I want to get the number of all documents in the database.

I tried

Firestore.instance.collection('products').toString().length

but it didn't work.

Solution 1

Firebase doesn't officially give any function to retrieve the number of documents in a collection, instead you can get all the documents of the collection and get the length of it..

There are two ways:

1)

final int documents = await Firestore.instance.collection('products').snapshots().length;

This returns a value of int. But, if you don't use await, it returns a Future.

2)

final QuerySnapshot qSnap = await Firestore.instance.collection('products').getDocuments();
final int documents = qSnap.documents.length;

This returns a value of int.

However, these both methods gets all the documents in the collection and counts it.

Thank you

Solution 2

It Should Be - Firestore.instance.collection('products').snapshots().length.toString();

Solution 3

First, you have to get all the documents from that collection, then you can get the length of all the documents by document List. The below could should get the job done.

Firestore.instance.collection('products').getDocuments.then((myDocuments){
 print("${myDocuments.documents.length}");
});

Solution 4

 Future getCount({String id}) async => FirebaseFirestore.instance
      .collection(collection) //your collectionref
      .where('deleted', isEqualTo: false)
      .get()
      .then((value) {
    var count = 0;
    count = value.docs.length;

    return count;
  });

this is in dart language...

Solution 5

Since you are waiting on a future, this must be place within an async function

QuerySnapshot productCollection = await 
Firestore.instance.collection('products').get();
int productCount = productCollection.size();

Amount of documents in the collection

View more solutions

Comments

[Doug Stevenson]

Note that this will cause the client to download all of the documents in the collection just to get the count. For large collections, this could be extremely inefficient and costly.

[Olantobi]

@DougStevenson, What is the best way to get the count?

[Doug Stevenson]

@Olantobi The recommended solution is in the documentation. firebase.google.com/docs/firestore/solutions/counters

[Fayaz]

@DougStevenson is the counter method is similar to incrementing count, whenever a child is added?

[Robert Williams]

what if i have thousands of documents in each collection?

[Robert Williams]

how can u do this with remote config?

[Bisclavret]

This returns a type of Future<int>, so how do you do anything at all with this? It's not even valuable as a string, in the example you have provided, as it just shows errors, and the value of the string is "Instance of Future<int>"

[user3698694]

I think that's not going to work... as it would return the future int... where as you would need this in streambuilder or future builder. Please share the complete snippet

[Shaybc]

this solution can easily go out of sync (due to failed updates or malformed transaction isolation in the app side...), it is always a good practice to get a real data like a select count with a where clause or a Firestore.instance.collection('products').snapshots().length‌​; (snapshots() is a stream and wont cause downloading all the documents in the database if you don't want to)

[Joe Ferndz]

Please don't post only code as an answer, but also provide an explanation of what your code does and how it solves the problem of the question. Answers with an explanation are usually more helpful and of better quality, and are more likely to attract upvotes