A CollectionGroup
refers to all documents that are contained in a collection or subcollection with a specific collection ID.
CollectionGroup
Package
@google-cloud/firestoreConstructors
(constructor)(firestore, collectionId, converter)
constructor
(
firestore
:
Firestore
,
collectionId
:
string
,
converter
:
firestore
.
FirestoreDataConverter<AppModelType
,
DbModelType
>
|
undefined
);
Constructs a new instance of the CollectionGroup
class
firestore
collectionId
string
converter
FirebaseFirestore.FirestoreDataConverter
<AppModelType, DbModelType> | undefined
Methods
getPartitions(desiredPartitionCount)
getPartitions
(
desiredPartitionCount
:
number
)
:
AsyncIterable<QueryPartition<AppModelType
,
DbModelType
>> ;
Partitions a query by returning partition cursors that can be used to run the query in parallel. The returned cursors are split points that can be used as starting and end points for individual query invocations.
desiredPartitionCount
number
The desired maximum number of partition points. The number must be strictly positive. The actual number of partitions returned may be fewer. {AsyncIterable
const
query
=
firestore
.
collectionGroup
(
'collectionId'
);
for
await
(
const
partition
of
query
.
getPartitions
(
42
))
{
const
partitionedQuery
=
partition
.
toQuery
();
const
querySnapshot
=
await
partitionedQuery
.
get
();
console
.
log
(
`Partition contained
${
querySnapshot
.
length
}
documents`
);
}
withConverter(converter)
withConverter
(
converter
:
null
)
:
CollectionGroup
;
Applies a custom data converter to this CollectionGroup
, allowing you to use your own custom model objects with Firestore. When you call get() on the returned CollectionGroup
, the provided converter will convert between Firestore data of type NewDbModelType
and your custom type NewAppModelType
.
Using the converter allows you to specify generic type arguments when storing and retrieving objects from Firestore.
Passing in null
as the converter parameter removes the current converter.
converter
null
Converts objects to and from Firestore. Passing in null
removes the current converter. {CollectionGroup} A CollectionGroup
that uses the provided converter.
class
Post
{
constructor
(
readonly
title
:
string
,
readonly
author
:
string
)
{}
toString
()
:
string
{
return
this
.
title
+
', by '
+
this
.
author
;
}
}
const
postConverter
=
{
toFirestore
(
post
:
Post
)
:
FirebaseFirestore
.
DocumentData
{
return
{
title
:
post
.
title
,
author
:
post
.
author
};
},
fromFirestore
(
snapshot
:
FirebaseFirestore
.
QueryDocumentSnapshot
)
:
Post
{
const
data
=
snapshot
.
data
();
return
new
Post
(
data
.
title
,
data
.
author
);
}
};
const
querySnapshot
=
await
Firestore
()
.
collectionGroup
(
'posts'
)
.
withConverter
(
postConverter
)
.
get
();
for
(
const
doc
of
querySnapshot
.
docs
)
{
const
post
=
doc
.
data
();
post
.
title
;
// string
post
.
toString
();
// Should be defined
post
.
someNonExistentProperty
;
// TS error
}
withConverter(converter)
withConverter<NewAppModelType
,
NewDbModelType
extends
firestore
.
DocumentData
=
firestore
.
DocumentData
> (
converter
:
firestore
.
FirestoreDataConverter<NewAppModelType
,
NewDbModelType
> )
:
CollectionGroup<NewAppModelType
,
NewDbModelType
> ;
converter
FirebaseFirestore.FirestoreDataConverter
<NewAppModelType, NewDbModelType>
NewAppModelType
NewDbModelType
