io.realm.mongodb.mongo

Class MongoCollection<DocumentT>

java.lang.Object

io.realm.mongodb.mongo.MongoCollection<DocumentT>

Type Parameters:

DocumentT - The type that this collection will encode documents from and decode documents to.

public class MongoCollection<DocumentT>
extends Object

The MongoCollection interface provides read and write access to documents.

Use MongoDatabase.getCollection(java.lang.String) to get a collection instance.

Before any access is possible, there must be an active, logged-in user.

See Also:

MongoDatabase

Method Summary

Modifier and Type	Method and Description
AggregateIterable<DocumentT>	aggregate(List<? extends Bson> pipeline) Aggregates documents according to the specified aggregation pipeline.
<ResultT> AggregateIterable<ResultT>	aggregate(List<? extends Bson> pipeline, Class<ResultT> resultClass) Aggregates documents according to the specified aggregation pipeline specifying an output class.
RealmResultTask<Long>	count() Counts the number of documents in the collection.
RealmResultTask<Long>	count(Bson filter) Counts the number of documents in the collection according to the given options.
RealmResultTask<Long>	count(Bson filter, CountOptions options) Counts the number of documents in the collection according to the given options.
RealmResultTask<DeleteResult>	deleteMany(Bson filter) Removes all documents from the collection that match the given query filter.
RealmResultTask<DeleteResult>	deleteOne(Bson filter) Removes at most one document from the collection that matches the given filter.
FindIterable<DocumentT>	find() Finds all documents in the collection.
FindIterable<DocumentT>	find(Bson filter) Finds all documents in the collection that match the given filter.
<ResultT> FindIterable<ResultT>	find(Bson filter, Class<ResultT> resultClass) Finds all documents in the collection that match the given filter specifying an output class.
<ResultT> FindIterable<ResultT>	find(Bson filter, Class<ResultT> resultClass, FindOptions options) Finds all documents in the collection that match the given filter specifying an output class and also using FindOptions to build the query.
FindIterable<DocumentT>	find(Bson filter, FindOptions options) Finds all documents in the collection that match the given filter using FindOptions to build the query.
<ResultT> FindIterable<ResultT>	find(Class<ResultT> resultClass) Finds all documents in the collection specifying an output class.
<ResultT> FindIterable<ResultT>	find(Class<ResultT> resultClass, FindOptions options) Finds all documents in the collection specifying an output class and also using FindOptions to build the query.
FindIterable<DocumentT>	find(FindOptions options) Finds all documents in the collection using FindOptions to build the query.
RealmResultTask<DocumentT>	findOne() Finds a document in the collection.
RealmResultTask<DocumentT>	findOne(Bson filter) Finds a document in the collection.
<ResultT> RealmResultTask<ResultT>	findOne(Bson filter, Class<ResultT> resultClass) Finds a document in the collection.
RealmResultTask<DocumentT>	findOne(Bson filter, FindOptions options) Finds a document in the collection.
<ResultT> RealmResultTask<ResultT>	findOne(Bson filter, FindOptions options, Class<ResultT> resultClass) Finds a document in the collection.
<ResultT> RealmResultTask<ResultT>	findOne(Class<ResultT> resultClass) Finds a document in the collection.
RealmResultTask<DocumentT>	findOneAndDelete(Bson filter) Finds a document in the collection and delete it.
<ResultT> RealmResultTask<ResultT>	findOneAndDelete(Bson filter, Class<ResultT> resultClass) Finds a document in the collection and delete it.
RealmResultTask<DocumentT>	findOneAndDelete(Bson filter, FindOneAndModifyOptions options) Finds a document in the collection and delete it.
<ResultT> RealmResultTask<ResultT>	findOneAndDelete(Bson filter, FindOneAndModifyOptions options, Class<ResultT> resultClass) Finds a document in the collection and delete it.
RealmResultTask<DocumentT>	findOneAndReplace(Bson filter, Bson replacement) Finds a document in the collection and replaces it with the given document.
<ResultT> RealmResultTask<ResultT>	findOneAndReplace(Bson filter, Bson replacement, Class<ResultT> resultClass) Finds a document in the collection and replaces it with the given document.
RealmResultTask<DocumentT>	findOneAndReplace(Bson filter, Bson replacement, FindOneAndModifyOptions options) Finds a document in the collection and replaces it with the given document.
<ResultT> RealmResultTask<ResultT>	findOneAndReplace(Bson filter, Bson replacement, FindOneAndModifyOptions options, Class<ResultT> resultClass) Finds a document in the collection and replaces it with the given document.
RealmResultTask<DocumentT>	findOneAndUpdate(Bson filter, Bson update) Finds a document in the collection and performs the given update.
<ResultT> RealmResultTask<ResultT>	findOneAndUpdate(Bson filter, Bson update, Class<ResultT> resultClass) Finds a document in the collection and performs the given update.
RealmResultTask<DocumentT>	findOneAndUpdate(Bson filter, Bson update, FindOneAndModifyOptions options) Finds a document in the collection and performs the given update.
<ResultT> RealmResultTask<ResultT>	findOneAndUpdate(Bson filter, Bson update, FindOneAndModifyOptions options, Class<ResultT> resultClass) Finds a document in the collection and performs the given update.
CodecRegistry	getCodecRegistry() Gets the codec registry for the MongoCollection.
Class<DocumentT>	getDocumentClass() Gets the class of documents stored in this collection.
String	getName() Gets the name of this collection
MongoNamespace	getNamespace() Gets the namespace of this collection, i.e.
RealmResultTask<InsertManyResult>	insertMany(List<? extends DocumentT> documents) Inserts one or more documents.
RealmResultTask<InsertOneResult>	insertOne(DocumentT document) Inserts the provided document.
RealmResultTask<UpdateResult>	updateMany(Bson filter, Bson update) Update all documents in the collection according to the specified arguments.
RealmResultTask<UpdateResult>	updateMany(Bson filter, Bson update, UpdateOptions updateOptions) Update all documents in the collection according to the specified arguments.
RealmResultTask<UpdateResult>	updateOne(Bson filter, Bson update) Update a single document in the collection according to the specified arguments.
RealmResultTask<UpdateResult>	updateOne(Bson filter, Bson update, UpdateOptions updateOptions) Update a single document in the collection according to the specified arguments.
RealmEventStreamTask<DocumentT>	watch() Watches a collection.
RealmEventStreamTask<DocumentT>	watch(BsonValue... ids) Watches specified IDs in a collection.
RealmEventStreamTask<DocumentT>	watch(ObjectId... ids) Watches specified IDs in a collection.
RealmEventStreamAsyncTask<DocumentT>	watchAsync() Watches a collection asynchronously.
RealmEventStreamAsyncTask<DocumentT>	watchAsync(BsonValue... ids) Watches specified IDs in a collection asynchronously.
RealmEventStreamAsyncTask<DocumentT>	watchAsync(ObjectId... ids) Watches specified IDs in a collection asynchronously.
RealmEventStreamTask<DocumentT>	watchWithFilter(BsonDocument matchFilter) Watches a collection.
RealmEventStreamTask<DocumentT>	watchWithFilter(Document matchFilter) Watches a collection.
RealmEventStreamAsyncTask<DocumentT>	watchWithFilterAsync(BsonDocument matchFilter) Watches a collection asynchronously.
RealmEventStreamAsyncTask<DocumentT>	watchWithFilterAsync(Document matchFilter) Watches a collection asynchronously.
MongoCollection<DocumentT>	withCodecRegistry(CodecRegistry codecRegistry) Creates a new MongoCollection instance with a different codec registry.
<NewDocumentT> MongoCollection<NewDocumentT>	withDocumentClass(Class<NewDocumentT> clazz) Creates a new MongoCollection instance with a different default class to cast any documents returned from the database into.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getNamespace

public MongoNamespace getNamespace()

Gets the namespace of this collection, i.e. the database and collection names together.

Returns:

the namespace

getName

public String getName()

Gets the name of this collection

Returns:

the name

getDocumentClass

public Class<DocumentT> getDocumentClass()

Gets the class of documents stored in this collection.

If you used the simple MongoDatabase.getCollection(String) to get this collection, this is org.bson.Document.

Returns:

the class of documents in this collection

getCodecRegistry

public CodecRegistry getCodecRegistry()

Gets the codec registry for the MongoCollection.

Returns:

the CodecRegistry for this collection

withDocumentClass

public <NewDocumentT> MongoCollection<NewDocumentT> withDocumentClass(Class<NewDocumentT> clazz)

Creates a new MongoCollection instance with a different default class to cast any documents returned from the database into.

Type Parameters:

NewDocumentT - The type that the new collection will encode documents from and decode documents to.

Parameters:

clazz - the default class to which any documents returned from the database will be cast.

Returns:

a new MongoCollection instance with the different default class

withCodecRegistry

public MongoCollection<DocumentT> withCodecRegistry(CodecRegistry codecRegistry)

Creates a new MongoCollection instance with a different codec registry.

Parameters:

codecRegistry - the new CodecRegistry for the collection.

Returns:

a new MongoCollection instance with the different codec registry

count

public RealmResultTask<Long> count()

Counts the number of documents in the collection.

Returns:

a task containing the number of documents in the collection

count

public RealmResultTask<Long> count(Bson filter)

Counts the number of documents in the collection according to the given options.

Parameters:

filter - the query filter

Returns:

a task containing the number of documents in the collection

count

public RealmResultTask<Long> count(Bson filter,
                                   CountOptions options)

Counts the number of documents in the collection according to the given options.

Parameters:

filter - the query filter

options - the options describing the count

Returns:

a task containing the number of documents in the collection

findOne

public RealmResultTask<DocumentT> findOne()

Finds a document in the collection.

Returns:

a task containing the result of the find one operation

findOne

public <ResultT> RealmResultTask<ResultT> findOne(Class<ResultT> resultClass)

Finds a document in the collection.

Type Parameters:

ResultT - the target document type

Parameters:

resultClass - the class to decode each document into

Returns:

a task containing the result of the find one operation

findOne

public RealmResultTask<DocumentT> findOne(Bson filter)

Finds a document in the collection.

Parameters:

filter - the query filter

Returns:

a task containing the result of the find one operation

findOne

public <ResultT> RealmResultTask<ResultT> findOne(Bson filter,
                                                  Class<ResultT> resultClass)

Finds a document in the collection.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

resultClass - the class to decode each document into

Returns:

a task containing the result of the find one operation

findOne

public RealmResultTask<DocumentT> findOne(Bson filter,
                                          FindOptions options)

Finds a document in the collection.

Parameters:

filter - the query filter

options - a FindOptions struct

Returns:

a task containing the result of the find one operation

findOne

public <ResultT> RealmResultTask<ResultT> findOne(Bson filter,
                                                  FindOptions options,
                                                  Class<ResultT> resultClass)

Finds a document in the collection.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

options - a FindOptions struct

resultClass - the class to decode each document into

Returns:

a task containing the result of the find one operation

find

public FindIterable<DocumentT> find()

Finds all documents in the collection.

All documents will be delivered in the form of a FindIterable from which individual elements can be extracted.

Returns:

an iterable containing the result of the find operation

find

public FindIterable<DocumentT> find(FindOptions options)

Finds all documents in the collection using FindOptions to build the query.

All documents will be delivered in the form of a FindIterable from which individual elements can be extracted.

Parameters:

options - a FindOptions struct for building the query

Returns:

an iterable containing the result of the find operation

find

public <ResultT> FindIterable<ResultT> find(Class<ResultT> resultClass)

Finds all documents in the collection specifying an output class.

All documents will be delivered in the form of a FindIterable from which individual elements can be extracted.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

resultClass - the class to decode each document into

Returns:

an iterable containing the result of the find operation

find

public <ResultT> FindIterable<ResultT> find(Class<ResultT> resultClass,
                                            FindOptions options)

Finds all documents in the collection specifying an output class and also using FindOptions to build the query.

All documents will be delivered in the form of a FindIterable from which individual elements can be extracted.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

resultClass - the class to decode each document into

options - a FindOptions struct for building the query

Returns:

an iterable containing the result of the find operation

find

public FindIterable<DocumentT> find(Bson filter)

Finds all documents in the collection that match the given filter.

All documents will be delivered in the form of a FindIterable from which individual elements can be extracted.

Parameters:

filter - the query filter

Returns:

an iterable containing the result of the find operation

find

public FindIterable<DocumentT> find(Bson filter,
                                    FindOptions options)

Finds all documents in the collection that match the given filter using FindOptions to build the query.

All documents will be delivered in the form of a FindIterable from which individual elements can be extracted.

Parameters:

filter - the query filter

options - a FindOptions struct

Returns:

an iterable containing the result of the find operation

find

public <ResultT> FindIterable<ResultT> find(Bson filter,
                                            Class<ResultT> resultClass)

Finds all documents in the collection that match the given filter specifying an output class.

All documents will be delivered in the form of a FindIterable from which individual elements can be extracted.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

resultClass - the class to decode each document into

Returns:

an iterable containing the result of the find operation

find

public <ResultT> FindIterable<ResultT> find(Bson filter,
                                            Class<ResultT> resultClass,
                                            FindOptions options)

Finds all documents in the collection that match the given filter specifying an output class and also using FindOptions to build the query.

All documents will be delivered in the form of a FindIterable from which individual elements can be extracted.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

resultClass - the class to decode each document into

options - a FindOptions struct

Returns:

an iterable containing the result of the find operation

aggregate

public AggregateIterable<DocumentT> aggregate(List<? extends Bson> pipeline)

Aggregates documents according to the specified aggregation pipeline.

All documents will be delivered in the form of an AggregateIterable from which individual elements can be extracted.

Parameters:

pipeline - the aggregation pipeline

Returns:

an AggregateIterable from which the results can be extracted

aggregate

public <ResultT> AggregateIterable<ResultT> aggregate(List<? extends Bson> pipeline,
                                                      Class<ResultT> resultClass)

Aggregates documents according to the specified aggregation pipeline specifying an output class.

All documents will be delivered in the form of an AggregateIterable from which individual elements can be extracted.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

pipeline - the aggregation pipeline

resultClass - the class to decode each document into

Returns:

an AggregateIterable from which the results can be extracted

insertOne

public RealmResultTask<InsertOneResult> insertOne(DocumentT document)

Inserts the provided document. If the document is missing an identifier, the client should generate one.

Parameters:

document - the document to insert

Returns:

a task containing the result of the insert one operation

insertMany

public RealmResultTask<InsertManyResult> insertMany(List<? extends DocumentT> documents)

Inserts one or more documents.

Parameters:

documents - the documents to insert

Returns:

a task containing the result of the insert many operation

deleteOne

public RealmResultTask<DeleteResult> deleteOne(Bson filter)

Removes at most one document from the collection that matches the given filter. If no documents match, the collection is not modified.

Parameters:

filter - the query filter to apply the the delete operation

Returns:

a task containing the result of the remove one operation

deleteMany

public RealmResultTask<DeleteResult> deleteMany(Bson filter)

Removes all documents from the collection that match the given query filter. If no documents match, the collection is not modified.

Parameters:

filter - the query filter to apply the the delete operation

Returns:

a task containing the result of the remove many operation

updateOne

public RealmResultTask<UpdateResult> updateOne(Bson filter,
                                               Bson update)

Update a single document in the collection according to the specified arguments.

Parameters:

filter - a document describing the query filter, which may not be null.

update - a document describing the update, which may not be null. The update to apply must include only update operators.

Returns:

a task containing the result of the update one operation

updateOne

public RealmResultTask<UpdateResult> updateOne(Bson filter,
                                               Bson update,
                                               UpdateOptions updateOptions)

Update a single document in the collection according to the specified arguments.

Parameters:

filter - a document describing the query filter, which may not be null.

update - a document describing the update, which may not be null. The update to apply must include only update operators.

updateOptions - the options to apply to the update operation

Returns:

a task containing the result of the update one operation

updateMany

public RealmResultTask<UpdateResult> updateMany(Bson filter,
                                                Bson update)

Update all documents in the collection according to the specified arguments.

Parameters:

filter - a document describing the query filter, which may not be null.

update - a document describing the update, which may not be null. The update to apply must include only update operators.

Returns:

a task containing the result of the update many operation

updateMany

public RealmResultTask<UpdateResult> updateMany(Bson filter,
                                                Bson update,
                                                UpdateOptions updateOptions)

Update all documents in the collection according to the specified arguments.

Parameters:

filter - a document describing the query filter, which may not be null.

update - a document describing the update, which may not be null. The update to apply must include only update operators.

updateOptions - the options to apply to the update operation

Returns:

a task containing the result of the update many operation

findOneAndUpdate

public RealmResultTask<DocumentT> findOneAndUpdate(Bson filter,
                                                   Bson update)

Finds a document in the collection and performs the given update.

Parameters:

filter - the query filter

update - the update document

Returns:

a task containing the resulting document

findOneAndUpdate

public <ResultT> RealmResultTask<ResultT> findOneAndUpdate(Bson filter,
                                                           Bson update,
                                                           Class<ResultT> resultClass)

Finds a document in the collection and performs the given update.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

update - the update document

resultClass - the class to decode each document into

Returns:

a task containing the resulting document

findOneAndUpdate

public RealmResultTask<DocumentT> findOneAndUpdate(Bson filter,
                                                   Bson update,
                                                   FindOneAndModifyOptions options)

Finds a document in the collection and performs the given update.

Parameters:

filter - the query filter

update - the update document

options - a FindOneAndModifyOptions struct

Returns:

a task containing the resulting document

findOneAndUpdate

public <ResultT> RealmResultTask<ResultT> findOneAndUpdate(Bson filter,
                                                           Bson update,
                                                           FindOneAndModifyOptions options,
                                                           Class<ResultT> resultClass)

Finds a document in the collection and performs the given update.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

update - the update document

options - a FindOneAndModifyOptions struct

resultClass - the class to decode each document into

Returns:

a task containing the resulting document

findOneAndReplace

public RealmResultTask<DocumentT> findOneAndReplace(Bson filter,
                                                    Bson replacement)

Finds a document in the collection and replaces it with the given document.

Parameters:

filter - the query filter

replacement - the document to replace the matched document with

Returns:

a task containing the resulting document

findOneAndReplace

public <ResultT> RealmResultTask<ResultT> findOneAndReplace(Bson filter,
                                                            Bson replacement,
                                                            Class<ResultT> resultClass)

Finds a document in the collection and replaces it with the given document.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

replacement - the document to replace the matched document with

resultClass - the class to decode each document into

Returns:

a task containing the resulting document

findOneAndReplace

public RealmResultTask<DocumentT> findOneAndReplace(Bson filter,
                                                    Bson replacement,
                                                    FindOneAndModifyOptions options)

Finds a document in the collection and replaces it with the given document.

Parameters:

filter - the query filter

replacement - the document to replace the matched document with

options - a FindOneAndModifyOptions struct

Returns:

a task containing the resulting document

findOneAndReplace

public <ResultT> RealmResultTask<ResultT> findOneAndReplace(Bson filter,
                                                            Bson replacement,
                                                            FindOneAndModifyOptions options,
                                                            Class<ResultT> resultClass)

Finds a document in the collection and replaces it with the given document.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

replacement - the document to replace the matched document with

options - a FindOneAndModifyOptions struct

resultClass - the class to decode each document into

Returns:

a task containing the resulting document

findOneAndDelete

public RealmResultTask<DocumentT> findOneAndDelete(Bson filter)

Finds a document in the collection and delete it.

Parameters:

filter - the query filter

Returns:

a task containing the resulting document

findOneAndDelete

public <ResultT> RealmResultTask<ResultT> findOneAndDelete(Bson filter,
                                                           Class<ResultT> resultClass)

Finds a document in the collection and delete it.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

resultClass - the class to decode each document into

Returns:

a task containing the resulting document

findOneAndDelete

public RealmResultTask<DocumentT> findOneAndDelete(Bson filter,
                                                   FindOneAndModifyOptions options)

Finds a document in the collection and delete it.

Parameters:

filter - the query filter

options - a FindOneAndModifyOptions struct

Returns:

a task containing the resulting document

findOneAndDelete

public <ResultT> RealmResultTask<ResultT> findOneAndDelete(Bson filter,
                                                           FindOneAndModifyOptions options,
                                                           Class<ResultT> resultClass)

Finds a document in the collection and delete it.

Type Parameters:

ResultT - the target document type of the iterable.

Parameters:

filter - the query filter

options - a FindOneAndModifyOptions struct

resultClass - the class to decode each document into

Returns:

a task containing the resulting document

watch

public RealmEventStreamTask<DocumentT> watch()

Watches a collection. The resulting stream will be notified of all events on this collection that the active user is authorized to see based on the configured MongoDB Realm rules.

Returns:

a task that provides access to the stream of change events.

watch

public RealmEventStreamTask<DocumentT> watch(BsonValue... ids)

Watches specified IDs in a collection.

Parameters:

ids - the ids to watch.

Returns:

a task that provides access to the stream of change events.

watch

public RealmEventStreamTask<DocumentT> watch(ObjectId... ids)

Watches specified IDs in a collection. This convenience overload supports the use case of non-BsonValue instances of ObjectId by wrapping them in BsonObjectId instances for the user.

Parameters:

ids - unique object identifiers of the IDs to watch.

Returns:

a task that provides access to the stream of change events.

watchWithFilter

public RealmEventStreamTask<DocumentT> watchWithFilter(Document matchFilter)

Watches a collection. The provided document will be used as a match expression filter on the change events coming from the stream. This convenience overload supports the use of non-BsonDocument instances for the user.

See how to define a match filter.

Defining the match expression to filter ChangeEvents is similar to how to define the match expression for triggers

Parameters:

matchFilter - the $match filter to apply to incoming change events

Returns:

a task that provides access to the stream of change events.

watchWithFilter

public RealmEventStreamTask<DocumentT> watchWithFilter(BsonDocument matchFilter)

Watches a collection. The provided BSON document will be used as a match expression filter on the change events coming from the stream.

See how to define a match filter.

Defining the match expression to filter ChangeEvents is similar to how to define the match expression for triggers

Parameters:

matchFilter - the $match filter to apply to incoming change events

Returns:

a task that provides access to the stream of change events.

watchAsync

public RealmEventStreamAsyncTask<DocumentT> watchAsync()

Watches a collection asynchronously. The resulting stream will be notified of all events on this collection that the active user is authorized to see based on the configured MongoDB Realm rules.

Returns:

a task that provides access to the stream of change events.

watchAsync

public RealmEventStreamAsyncTask<DocumentT> watchAsync(BsonValue... ids)

Watches specified IDs in a collection asynchronously.

Parameters:

ids - the ids to watch.

Returns:

a task that provides access to the stream of change events.

watchAsync

public RealmEventStreamAsyncTask<DocumentT> watchAsync(ObjectId... ids)

Watches specified IDs in a collection asynchronously. This convenience overload supports the use case of non-BsonValue instances of ObjectId by wrapping them in BsonObjectId instances for the user.

Parameters:

ids - unique object identifiers of the IDs to watch.

Returns:

a task that provides access to the stream of change events.

watchWithFilterAsync

public RealmEventStreamAsyncTask<DocumentT> watchWithFilterAsync(Document matchFilter)

Watches a collection asynchronously. The provided document will be used as a match expression filter on the change events coming from the stream. This convenience overload supports the use of non-BsonDocument instances for the user.

See how to define a match filter.

Defining the match expression to filter ChangeEvents is similar to how to define the match expression for triggers

Parameters:

matchFilter - the $match filter to apply to incoming change events

Returns:

a task that provides access to the stream of change events.

watchWithFilterAsync

public RealmEventStreamAsyncTask<DocumentT> watchWithFilterAsync(BsonDocument matchFilter)

Watches a collection asynchronously. The provided BSON document will be used as a match expression filter on the change events coming from the stream.

See how to define a match filter.

Defining the match expression to filter ChangeEvents is similar to how to define the match expression for triggers

Parameters:

matchFilter - the $match filter to apply to incoming change events

Returns:

a task that provides access to the stream of change events.