Get number of documents in collection firestore
Question:
Is it possible to count how many documents a collection in Firestore has, using python?
I just found this code
functions.firestore.document('collection/{documentUid}')
.onWrite((change, context) => {
if (!change.before.exists) {
// New document Created : add one to count
db.doc(docRef).update({numberOfDocs: FieldValue.increment(1)});
} else if (change.before.exists && change.after.exists) {
// Updating existing document : Do nothing
} else if (!change.after.exists) {
// Deleting document : subtract one from count
db.doc(docRef).update({numberOfDocs: FieldValue.increment(-1)});
}
return;
});
How I can do this with python?
Answers:
Firestore (like many NoSQL databases) has no built in aggregation queries. If you want to determine the number of documents, you have two main options:
- Read all documents, and then count them in the client.
- Keep the document count in the database itself, and then update it with every add/delete operation.
While the firsts option is simpler, it is less scalable as you’ll end up with clients reading all documents just to determine the count. That’s why you’ll find most questions/articles about counting documents focusing on the second approach.
For more on this, see:
- The Firestore documentation on aggregation queries.
- The Firestore documentation on distributed counters, which you’ll need to consider if your count changes more frequently than about once per second.
New in February 2023
Firestore now has added the count() method to queries and collections in the Python SDK.
Usage
The documentation does not say much about it at the moment, but here is how I manage to use it.
You need firebase-admin in 6.1.0 or later.
Init
from firebase_admin import firestore
# do the credentials stuff if necessary
db = firestore.client()
Count docs in collection
my_collection = db.collection("foo")
count_query = my_collection.count()
query_result = count_query.get()
print("Nb docs in collection:", query_result[0][0].value)
Count docs from query
simple_query = db.collection("foo").where("myField", "==", 0)
count_query = simple_query.count()
query_result = count_query.get()
print("Nb docs in query:", query_result[0][0].value)
Is it possible to count how many documents a collection in Firestore has, using python?
I just found this code
functions.firestore.document('collection/{documentUid}')
.onWrite((change, context) => {
if (!change.before.exists) {
// New document Created : add one to count
db.doc(docRef).update({numberOfDocs: FieldValue.increment(1)});
} else if (change.before.exists && change.after.exists) {
// Updating existing document : Do nothing
} else if (!change.after.exists) {
// Deleting document : subtract one from count
db.doc(docRef).update({numberOfDocs: FieldValue.increment(-1)});
}
return;
});
How I can do this with python?
Firestore (like many NoSQL databases) has no built in aggregation queries. If you want to determine the number of documents, you have two main options:
- Read all documents, and then count them in the client.
- Keep the document count in the database itself, and then update it with every add/delete operation.
While the firsts option is simpler, it is less scalable as you’ll end up with clients reading all documents just to determine the count. That’s why you’ll find most questions/articles about counting documents focusing on the second approach.
For more on this, see:
- The Firestore documentation on aggregation queries.
- The Firestore documentation on distributed counters, which you’ll need to consider if your count changes more frequently than about once per second.
New in February 2023
Firestore now has added the count() method to queries and collections in the Python SDK.
Usage
The documentation does not say much about it at the moment, but here is how I manage to use it.
You need firebase-admin in 6.1.0 or later.
Init
from firebase_admin import firestore
# do the credentials stuff if necessary
db = firestore.client()
Count docs in collection
my_collection = db.collection("foo")
count_query = my_collection.count()
query_result = count_query.get()
print("Nb docs in collection:", query_result[0][0].value)
Count docs from query
simple_query = db.collection("foo").where("myField", "==", 0)
count_query = simple_query.count()
query_result = count_query.get()
print("Nb docs in query:", query_result[0][0].value)