DatabasePublished

@propertyWrapper
public class DatabasePublished<Output> : Publisher

DatabasePublished is a property wrapper whose value automatically changes, on the main queue, when the database is modified.

Usage:

class MyModel {
    // A DatabasePublishers.Value
    static let playersPublisher = Player.observationForAll().publisher(in: dbQueue)

    @DatabasePublished(playersPublisher)
    var players: Result<[Players], Error>
}

let model = MyModel()
try model.players.get() // [Player]
model.$players          // Publisher of output [Player], failure Error

By default, the initial value of the property is immediately fetched from the database. This blocks your main queue until the database access completes.

You can opt in for an asynchronous fetching by providing an initial value:

class MyModel {
    // The initialValue argument triggers asynchronous fetching
    @DatabasePublished(initialValue: [], playersPublisher)
    var players: Result<[Players], Error>
}

let model = MyModel()
// Empty array until the initial fetch is performed
try model.players.get()

DatabasePublished is a reference type which tracks changes the database during its whole life time. It is not advised to use it in a value type such as a struct.