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import CoreData
import RxSwift
import QueryKit
import Foundation
private func managedObjectMatchesEntity(_ entityNames: [String]) -> (NSManagedObject) -> Bool {
return { object in
if let name = object.entity.name {
return entityNames.contains(name)
}
return false
}
}
/// Extension to QuerySet to provide observables
extension QuerySet {
fileprivate var entityNames: [String] {
if let entity = NSEntityDescription.entity(forEntityName: entityName, in: context) {
return [entityName] + entity.subentitiesByName.keys
}
return [entityName]
}
/// Performs a query for all objects matching the set predicate ordered by any set sort descriptors.
/// Emits a value with an array of all objects when the managed object context is changed.
public func objects() throws -> Observable<[ModelType]> {
let initial = try self.array()
let filter = managedObjectMatchesEntity(entityNames)
return Observable.create { observer in
observer.on(.next(initial))
return self.context.qk_objectsDidChange().subscribe(onNext: { notification in
let insertedObjects = notification.insertedObjects.filter(filter)
let updatedObjects = notification.updatedObjects.filter(filter)
let deletedObjects = notification.deletedObjects.filter(filter)
if insertedObjects.isEmpty && updatedObjects.isEmpty && deletedObjects.isEmpty {
return
}
do {
let objects = try self.array()
observer.onNext(objects)
} catch {
observer.onError(error)
}
})
}
}
/// Performs a query for the count of all objects matching the set predicate.
/// Emits an Int containing the amount of objects matching the predicate and updates when the managed object context is changed.
public func count() throws -> Observable<Int> {
var count: Int = try self.count()
let filter = managedObjectMatchesEntity(entityNames)
return Observable.create { observer in
observer.on(.next(count))
return self.context.qk_objectsDidChange().subscribe(onNext: { notification in
let updatedObjects = notification.updatedObjects.filter(filter)
if !updatedObjects.isEmpty && self.predicate != nil {
do {
count = try self.count()
observer.onNext(count)
} catch {
observer.onError(error)
}
return
}
let insertedObjects = notification.insertedObjects.filter(filter)
let deletedObjects = notification.deletedObjects.filter(filter)
var delta = 0
if let predicate = self.predicate {
delta += insertedObjects.filter(predicate.evaluate).count
delta -= deletedObjects.filter(predicate.evaluate).count
} else {
delta += insertedObjects.count
delta -= deletedObjects.count
}
if delta != 0 {
count += delta
observer.on(.next(count))
}
})
}
}
}