Description
Returns all documents from any collection with the specified collection ID, regardless of its parent.
Examples
Web
const results = await execute ( db . pipeline () . collectionGroup ( "games" ) . sort ( field ( "name" ). ascending ()) );
Swift
let results = try await db . pipeline () . collectionGroup ( "games" ) . sort ([ Field ( "name" ). ascending ()]) . execute ()
Kotlin
val results = db . pipeline () . collectionGroup ( "games" ) . sort ( field ( "name" ). ascending ()) . execute ()
Java
Task<Pipeline . Snapshot > results = db . pipeline () . collectionGroup ( "games" ) . sort ( field ( "name" ). ascending ()) . execute ();
Python
from google.cloud.firestore_v1.pipeline_expressions import Field results = ( client . pipeline () . collection_group ( "games" ) . sort ( Field . of ( "name" ) . ascending ()) . execute () )
Java
Pipeline . Snapshot results = firestore . pipeline () . collectionGroup ( "games" ) . sort ( ascending ( field ( "name" ))) . execute () . get ();
Behavior
In order to use the collection_group(...)
stage, it must appear as the first
stage in the pipeline.
The order of documents returned from the collection_group(...)
stage is
unstable and cannot be relied upon. Cloud Firestore
will attempt to
execute the query in the most efficient way possible, which can change the order
depending on the schema or index configuration. A subsequent sort(...)
stage
can be used to obtain a deterministic ordering.
For example, for the following documents:
Node.js
await
db
.
collection
(
"cities/SF/departments"
).
doc
(
"building"
).
set
({
name
:
"SF Building Deparment"
,
employees
:
750
});
await
db
.
collection
(
"cities/NY/departments"
).
doc
(
"building"
).
set
({
name
:
"NY Building Deparment"
,
employees
:
1000
});
await
db
.
collection
(
"cities/CHI/departments"
).
doc
(
"building"
).
set
({
name
:
"CHI Building Deparment"
,
employees
:
900
});
await
db
.
collection
(
"cities/NY/departments"
).
doc
(
"finance"
).
set
({
name
:
"NY Finance Deparment"
,
employees
:
1200
});
The collection_group(...)
stage can be used to return documents from every
departments collection across all parent collections in the database.
Node.js
const
results
=
await
db
.
pipeline
()
.
collectionGroup
(
"departments"
)
.
sort
(
field
(
"employees"
).
ascending
())
.
execute
();
This query produces the following documents:
{
name
:
"SF Building Deparment"
,
employees
:
750
}
{
name
:
"CHI Building Deparment"
,
employees
:
900
}
{
name
:
"NY Building Deparment"
,
employees
:
1000
}
{
name
:
"NY Finance Deparment"
,
employees
:
1200
}
