DittoPendingCollectionsOperation

These objects are returned when calling collections() on DittoStore.

They allow chaining of further collections-related functions. You can either call exec on the object to get an array of DittoCollections 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 observeLocal, will notify you every time there’s a change in the collections that the device knows about.

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 the collections that they know about.

Typically, an app would set up a subscribe in some part of the application which is long-lived to ensure the device receives updates from the mesh. These updates will be automatically received and written into the local store. Elsewhere, where you need to use this data, an observeLocal can be used to notify you of the data, and all subsequent changes to the data.

If you want to observe changes in such a way that you can signal when you’re ready for the live query to deliver a new update then you can call observeLocalWithNextSignal.

  • Limit the number of collections that get returned.

  • Sort the collections based on a property of the collection.

  • Offset the resulting set of collections.

    This is useful if you aren’t interested in the first N collections for one reason or another. For example, you might already have obtained the first 20 collections and so you might want to get the next 20 collections, and that is when you would use offset.

  • Subscribes the device to updates about collections that other devices know about.

    The returned DittoSubscription object must be kept in scope for as long as you want to keep receiving updates.

  • Return the list of collections requested based on the preceding function chaining.

  • Enables you to listen for changes that occur in relation to the collections that are known about locally.

    This won’t subscribe to receive updates from other devices and so it will only fires when a local change to the known about collections occurs. If you want to receive remote updates as well then also call subscribe.

    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.

  • Enables you to listen for changes that occur in relation to the collections that are known about locally. You can signal when you are ready for the next event to be delivered.

    This won’t subscribe to receive updates from other devices and so it will only fires when a local change to the known about collections occurs. If you want to receive remote updates as well then also call subscribe.

    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.