ditto-lib / live.ditto / DittoPendingCursorOperation

DittoPendingCursorOperation

class DittoPendingCursorOperation

These objects are returned when using find-like functionality on DittoCollections. They allow chaining of further query-related functions to do things like add a limit to the number of documents you want returned or specify how you want the documents to be sorted and ordered. You can either call exec on the object to get an array of DittoDocuments as an immediate return value, or you can establish either a live query or a subscription, which both work over time. A live query, established by calling observe, will notify you every time there's an update to a document that matches the query you provided in the preceding find-like call. A subscription, established by calling subscribe, will act as a signal to other peers that the device connects to that you would like to receive updates from them about documents that match the query you provided in the preceding find-like call. Calling observe will generate both a subscription and a live query at the same time. If you'd like to only observe local changes then you can call observeLocal. Update and remove functionality is also exposed through this object.

Properties

collectionName	`val collectionName: String` the name of the collection that the operation will be performed on.
limit	`var limit: Int`
offset	`var offset: Int`
orderDefinitions	`var orderDefinitions: MutableList<Ditto_OrderDefinition>`
query	`val query: String` the query that will be used when performing the operation.

Functions

evict	`fun evict(): List<String>` Evict all documents that match the query generated by the preceding function chaining.
exec	`fun exec(): List<DittoDocument>` Execute the query generated by the preceding function chaining and return the list of matching documents.
limit	`fun limit(limit: Int): DittoPendingCursorOperation` Limit the number of documents that get returned when querying a collection for matching documents.
observe	`fun observe(eventHandler: (List<DittoDocument>, DittoLiveQueryEvent) -> Unit): DittoLiveQuery` Enables you to listen for changes that occur on a collection. The `eventHandler` closure will be called when local or remote changes are made to documents that match the query generated by the chain of operations that precedes the call to `observe`. The returned DittoLiveQuery object must be kept in scope for as long as you want the provided `eventHandler` to be called when an update occurs. `fun observe(callback: DittoLiveQueryCallback): DittoLiveQuery` Enables you to listen for changes that occur on a collection. The `eventHandler` closure will be called when local or remote changes are made to documents that match the query generated by the chain of operations that precedes the call to `observe`. The returned DittoLiveQuery object must be kept in scope for as long as you want the provided `eventHandler` to be called when an update occurs.
observeLocal	`fun observeLocal(eventHandler: (List<DittoDocument>, DittoLiveQueryEvent) -> Unit): DittoLiveQuery` `fun observeLocal(callback: DittoLiveQueryCallback): DittoLiveQuery` Enables you to listen for changes that occur on a collection. This won't subscribe to receive changes made remotely by others and so it will only fire updates when a local change is made. If you want to receive remotely performed updates as well then use `observe` or call `subscribe` with the relevant query. The returned DittoLiveQuery object must be kept in scope for as long as you want the provided `eventHandler` to be called when an update occurs.
offset	`fun offset(offset: Int): DittoPendingCursorOperation` Offset the resulting set of matching documents. This is useful if you aren't interested in the first N matching documents for one reason or another. For example, you might already have queried the collection and obtained the first 20 matching documents and so you might want to run the same query as you did previously but ignore the first 20 matching documents, and that is where you would use `offset`.
remove	`fun remove(): List<String>` Remove all documents that match the query generated by the preceding function chaining.
sort	`fun sort(query: String, direction: DittoSortDirection): DittoPendingCursorOperation` Sort the documents that match the query provided in the preceding `find`-like function call.
subscribe	`fun subscribe(): DittoSubscription` Enables you to subscribe to changes that occur on a collection. Having a subscription acts as a signal to others that you are interested in receiving updates when local or remote changes are made to documents that match the query generated by the chain of operations that precedes the call to `subscribe`. The returned DittoSubscription object must be kept in scope for as long as you want to keep receiving updates.
update	`fun update(closure: (List<DittoMutableDocument>) -> Unit): Map<String, List<DittoUpdateResult>>` `fun update(updater: DittoMutableDocumentsUpdater): Map<String, List<DittoUpdateResult>>` Update documents that match the query generated by the preceding function chaining.