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/**
* https://gist.github.com/tadija/6003830264d67a87193ff0c3d20373e7
* Copyright © 2018-2019 Marko Tadić
* Licensed under the MIT license
*/
import CoreData
@available(iOS 10.0, *)
public extension NSFetchRequestResult where Self: NSManagedObject {
// MARK: Queries
static func findOrCreate(with predicate: NSPredicate? = nil,
in context: NSManagedObjectContext) -> Self {
return find(with: predicate, in: context) ?? self.init(context: context)
}
static func find(key: String,
value: Any,
in context: NSManagedObjectContext?) -> Self? {
return find(with: predicate(key: key, value: value), in: context)
}
static func find(with predicate: NSPredicate? = nil,
in context: NSManagedObjectContext?) -> Self? {
if let objectFromMemory = context?.registeredObjects.first(where: {
let isFulfilled = !$0.isFault
let matchesPredicate = predicate?.evaluate(with: $0 as? Self) ?? false
return isFulfilled && matchesPredicate
}) as? Self {
/// - Note: since object is already in memory
/// this is way more performant than making a fetch request
return objectFromMemory
} else {
return all(with: predicate, limit: 1, in: context).first
}
}
static func incrementedInteger(for attribute: String,
in context: NSManagedObjectContext?) -> Int {
let sortDescriptor = NSSortDescriptor(key: attribute, ascending: false)
guard
let object = all(orderedBy: [sortDescriptor], limit: 1, in: context).first,
let max = object.value(forKey: attribute) as? Int
else {
return 0
}
return max + 1
}
static func all(with predicate: NSPredicate? = nil,
orderedBy sortDescriptors: [NSSortDescriptor] = [],
limit: Int? = nil,
in context: NSManagedObjectContext?) -> [Self] {
guard let context = context else {
return []
}
let request = fetchRequest(
predicate: predicate,
sortDescriptors: sortDescriptors,
limit: limit
)
let result = try? fetch(request, in: context)
return result ?? []
}
static func unmanaged() -> Self {
return self.init(
entity: self.entity(),
insertInto: nil
)
}
func `in`(_ context: NSManagedObjectContext?) -> Self? {
guard
let context = context,
let object = context.object(with: objectID) as? Self
else {
return nil
}
return object
}
// MARK: Predicate & Fetch Request
static func predicate(key: String, value: Any) -> NSPredicate {
return NSPredicate(format: "%K = %@", argumentArray: [key, value])
}
static func predicate(attributes: [String: Any],
type: NSCompoundPredicate.LogicalType = .and) -> NSPredicate {
let predicates = attributes.map {
predicate(key: $0.key, value: $0.value)
}
let compoundPredicate = NSCompoundPredicate(type: type, subpredicates: predicates)
return compoundPredicate
}
static func fetchRequest(
predicate: NSPredicate? = nil,
sortDescriptors: [NSSortDescriptor] = [],
limit: Int? = nil,
offset: Int? = nil,
batchSize: Int? = nil,
relationshipKeyPathsForPrefetching: [String] = []
) -> NSFetchRequest<Self> {
let entityName = String(describing: Self.self)
let request = NSFetchRequest<Self>(entityName: entityName)
request.predicate = predicate
request.sortDescriptors = sortDescriptors
request.fetchLimit = limit ?? request.fetchLimit
request.fetchOffset = offset ?? request.fetchOffset
request.fetchBatchSize = batchSize ?? request.fetchBatchSize
request.relationshipKeyPathsForPrefetching = relationshipKeyPathsForPrefetching
return request
}
static func fetch(_ request: NSFetchRequest<Self> = fetchRequest(),
in context: NSManagedObjectContext) throws -> [Self] {
return try context.fetch(request)
}
// MARK: Batch Update & Delete
@discardableResult
static func batchUpdate(
properties: [String: Any],
predicate: NSPredicate? = nil,
resultType: NSBatchUpdateRequestResultType = .updatedObjectsCountResultType,
in context: NSManagedObjectContext
) -> NSBatchUpdateResult? {
let request = NSBatchUpdateRequest(entityName: String(describing: Self.self))
request.propertiesToUpdate = properties
request.predicate = predicate
request.resultType = resultType
do {
let result = try context.execute(request)
return result as? NSBatchUpdateResult
} catch {
return nil
}
}
@discardableResult
static func batchDelete(
with predicate: NSPredicate? = nil,
resultType: NSBatchDeleteRequestResultType = .resultTypeCount,
in context: NSManagedObjectContext
) -> NSBatchDeleteResult? {
typealias FetchRequestResult = NSFetchRequest<NSFetchRequestResult>
guard let request = fetchRequest(predicate: predicate) as? FetchRequestResult else {
return nil
}
let deleteRequest = NSBatchDeleteRequest(fetchRequest: request)
deleteRequest.resultType = resultType
do {
let result = try context.execute(deleteRequest)
return result as? NSBatchDeleteResult
} catch {
return nil
}
}
}
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