Files
CoreStore/Sources/Tweak.swift
2018-09-15 12:56:08 +09:00

71 lines
2.6 KiB
Swift

//
// Tweak.swift
// CoreStore
//
// Copyright © 2018 John Rommel Estropia
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
import Foundation
import CoreData
// MARK: - Tweak
/**
The `Tweak` clause allows fine-tuning the `NSFetchRequest` for a fetch or query.
Sample usage:
```
let employees = transaction.fetchAll(
From<MyPersonEntity>(),
Tweak { (fetchRequest) -> Void in
fetchRequest.includesPendingChanges = false
fetchRequest.fetchLimit = 5
}
)
```
*/
public struct Tweak: FetchClause, QueryClause, DeleteClause {
/**
The block to customize the `NSFetchRequest`
*/
public let closure: (_ fetchRequest: NSFetchRequest<NSFetchRequestResult>) -> Void
/**
Initializes a `Tweak` clause with a closure where the `NSFetchRequest` may be configured.
- Important: `Tweak`'s closure is executed only just before the fetch occurs, so make sure that any values captured by the closure is not prone to race conditions. Also, some utilities (such as `ListMonitor`s) may keep `FetchClause`s in memory and may thus introduce retain cycles if reference captures are not handled properly.
- parameter closure: the block to customize the `NSFetchRequest`
*/
public init(_ closure: @escaping (_ fetchRequest: NSFetchRequest<NSFetchRequestResult>) -> Void) {
self.closure = closure
}
// MARK: FetchClause, QueryClause, DeleteClause
public func applyToFetchRequest<ResultType>(_ fetchRequest: NSFetchRequest<ResultType>) {
self.closure(fetchRequest as! NSFetchRequest<NSFetchRequestResult>)
}
}