Added ability to use non-contiguous transactions to be done on the main thread. This is useful for temporary changes such as partial input forms.

HardcoreData/BaseDataTransaction.swift

@@ -0,0 +1,118 @@
+//
+//  BaseDataTransaction.swift
+//  HardcoreData
+//
+//  Copyright (c) 2014 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
+import GCDKit
+
+
+// MARK: - BaseDataTransaction
+
+/**
+The BaseDataTransaction is an abstract interface for NSManagedObject creates, updates, and deletes. All BaseDataTransaction subclasses manage a private NSManagedObjectContext which are direct children of the NSPersistentStoreCoordinator's root NSManagedObjectContext. This means that all updates are saved first to the persistent store, and then propagated up to the read-only NSManagedObjectContext.
+*/
+public /*abstract*/ class BaseDataTransaction {
+    
+    // MARK: Object management
+    
+    var hasChanges: Bool {
+        
+        return self.context.hasChanges
+    }
+    
+    /**
+    Creates a new NSManagedObject with the specified entity type.
+    
+    :param: entity the NSManagedObject type to be created
+    :returns: a new NSManagedObject instance of the specified entity type.
+    */
+    public func create<T: NSManagedObject>(entity: T.Type) -> T {
+        
+        HardcoreData.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to create an entity of type <\(entity)> outside a transaction queue.")
+        
+        return T.createInContext(self.context)
+    }
+    
+    /**
+    Returns an editable proxy of a specified NSManagedObject.
+    
+    :param: object the NSManagedObject type to be edited
+    :returns: an editable proxy for the specified NSManagedObject.
+    */
+    public func fetch<T: NSManagedObject>(object: T) -> T? {
+        
+        HardcoreData.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to update an entity of type <\(object.dynamicType)> outside a transaction queue.")
+        
+        return object.inContext(self.context)
+    }
+    
+    /**
+    Deletes a specified NSManagedObject.
+    
+    :param: object the NSManagedObject type to be deleted
+    */
+    public func delete(object: NSManagedObject) {
+        
+        HardcoreData.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to delete an entity of type <\(object.dynamicType)> outside a transaction queue.")
+        
+        object.deleteFromContext()
+    }
+    
+    // MARK: Saving changes
+    
+    /**
+    Rolls back the transaction by resetting the NSManagedObjectContext. After calling this method, all NSManagedObjects fetched within the transaction will become invalid.
+    */
+    public func rollback() {
+        
+        HardcoreData.assert(self.transactionQueue.isCurrentExecutionContext(), "Attempted to rollback a <\(self.dynamicType)> outside a transaction queue.")
+        
+        self.context.reset()
+    }
+    
+    
+    // MARK: Internal
+    
+    internal let context: NSManagedObjectContext
+    internal let transactionQueue: GCDQueue
+    internal let childTransactionQueue: GCDQueue = .createSerial("com.hardcoredata.datastack.childtransactionqueue")
+    
+    internal var isCommitted = false
+    internal var result: SaveResult?
+    
+    internal init(mainContext: NSManagedObjectContext, queue: GCDQueue) {
+        
+        self.transactionQueue = queue
+        
+        let context = mainContext.temporaryContextInTransactionWithConcurrencyType(
+            queue == .Main
+                ? .MainQueueConcurrencyType
+                : .PrivateQueueConcurrencyType
+        )
+        self.context = context
+        
+        context.parentTransaction = self
+    }
+}