Struct Watch 

pub struct Watch<'a, T = Document, S = ImplicitSession> { /* private fields */ }

Starts a new ChangeStream that receives events for all changes in a given scope. Create by calling Client::watch, Database::watch, or Collection::watch.

Implementations

impl<S> Watch<'_, S>

pub fn pipeline(self, value: impl IntoIterator<Item = Document>) -> Watch<'_, S>

Apply an aggregation pipeline to the change stream.

Note that using a $project stage to remove any of the _id, operationType or ns fields will cause an error. The driver requires these fields to support resumability. For more information on resumability, see the documentation for ChangeStream

If the pipeline alters the structure of the returned events, the parsed type will need to be changed via ChangeStream::with_type.

pub fn resume_after(self, value: impl Into<Option<ResumeToken>>) -> Watch<'_, S>

Specifies the logical starting point for the new change stream. Note that if a watched collection is dropped and recreated or newly renamed, start_after should be set instead. resume_after and start_after cannot be set simultaneously.

For more information on resuming a change stream see the documentation here

pub fn with_options( self, value: impl Into<Option<ChangeStreamOptions>>, ) -> Watch<'_, S>

Set all options. Note that this will replace all previous values set.

pub fn full_document(self, value: FullDocumentType) -> Watch<'_, S>

Configures how the ChangeStreamEvent::full_document field will be populated. By default, the field will be empty for updates.

pub fn full_document_before_change( self, value: FullDocumentBeforeChangeType, ) -> Watch<'_, S>

Configures how the ChangeStreamEvent::full_document_before_change field will be populated. By default, the field will be empty for updates.

pub fn start_at_operation_time(self, value: Timestamp) -> Watch<'_, S>

The change stream will only provide changes that occurred at or after the specified timestamp. Any command run against the server will return an operation time that can be used here.

pub fn start_after(self, value: ResumeToken) -> Watch<'_, S>

Takes a resume token and starts a new change stream returning the first notification after the token. This will allow users to watch collections that have been dropped and recreated or newly renamed collections without missing any notifications.

This feature is only available on MongoDB 4.2+.

See the documentation here for more information.

pub fn max_await_time(self, value: Duration) -> Watch<'_, S>

The maximum amount of time for the server to wait on new documents to satisfy a change stream query.

pub fn batch_size(self, value: u32) -> Watch<'_, S>

The number of documents to return per batch.

pub fn collation(self, value: Collation) -> Watch<'_, S>

Specifies a collation.

pub fn read_concern(self, value: ReadConcern) -> Watch<'_, S>

The read concern to use for the operation.

If none is specified, the read concern defined on the object executing this operation will be used.

pub fn selection_criteria(self, value: SelectionCriteria) -> Watch<'_, S>

The criteria used to select a server for this operation.

If none is specified, the selection criteria defined on the object executing this operation will be used.

pub fn show_expanded_events(self, value: bool) -> Watch<'_, S>

Enables the server to send the ‘expanded’ list of change stream events.

pub fn comment(self, value: impl Into<Bson>) -> Watch<'_, S>

Tags the query with an arbitrary Bson value to help trace the operation through the database profiler, currentOp and logs.

The comment can be any Bson value on server versions 4.4+. On lower server versions, the comment must be a Bson::String value.

impl<'a, T> Watch<'a, T>

pub fn session<'s>( self, session: impl Into<&'s mut ClientSession>, ) -> Watch<'a, T, ExplicitSession<'s>>

Use the provided [‘ClientSession’].

Trait Implementations

impl<'a, T> Action for Watch<'a, T>

where T: DeserializeOwned + Unpin + Send + Sync,

fn optional<Value>( self, value: Option<Value>, f: impl FnOnce(Self, Value) -> Self, ) -> Self

where Self: Sized,

If the value is Some, call the provided function on self. Convenient for chained updates with values that need to be set conditionally. For example:

impl<'a, T> Action for Watch<'a, T, ExplicitSession<'a>>

where T: DeserializeOwned + Unpin + Send + Sync,

fn optional<Value>( self, value: Option<Value>, f: impl FnOnce(Self, Value) -> Self, ) -> Self

where Self: Sized,

If the value is Some, call the provided function on self. Convenient for chained updates with values that need to be set conditionally. For example:

impl<'a, T> IntoFuture for Watch<'a, T>

where T: DeserializeOwned + Unpin + Send + Sync,

type Output = Result<ChangeStream<ChangeStreamEvent<T>>, Error>

The output that the future will produce on completion.

type IntoFuture = WatchFuture<'a, T>

Which kind of future are we turning this into?

fn into_future(self) -> <Watch<'a, T> as IntoFuture>::IntoFuture

Creates a future from a value.

impl<'a, T> IntoFuture for Watch<'a, T, ExplicitSession<'a>>

where T: DeserializeOwned + Unpin + Send + Sync,

type Output = Result<SessionChangeStream<ChangeStreamEvent<T>>, Error>

The output that the future will produce on completion.

type IntoFuture = WatchSessionFuture<'a, T>

Which kind of future are we turning this into?

fn into_future( self, ) -> <Watch<'a, T, ExplicitSession<'a>> as IntoFuture>::IntoFuture

Creates a future from a value.