elegant queries

HardcoreData/ObjectQuery.swift

@@ -0,0 +1,134 @@
+//
+//  ObjectQuery.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
+
+
+public typealias AttributeName = Selector
+
+public enum SortOrder {
+    
+    case Ascending(AttributeName)
+    case Descending(AttributeName)
+}
+
+public final class ObjectQuery<T: NSManagedObject> {
+    
+    public var fetchLimit: Int = 0
+    public var fetchOffset: Int = 0
+    public var fetchBatchSize: Int = 0
+    
+    public var entityName: String {
+        
+        return self.entity.entityName
+    }
+    
+    public func WHERE(predicate: NSPredicate) -> ObjectQuery<T> {
+        
+        if self.predicate != nil {
+            
+            HardcoreData.log(.Warning, message: "Attempted to set a Query's WHERE clause more than once. The last predicate set will be used.")
+        }
+        self.predicate = predicate
+        return self
+    }
+    
+    public func WHERE(value: Bool) -> ObjectQuery<T> {
+        
+        return self.WHERE(NSPredicate(value: value))
+    }
+    
+    public func WHERE(format: String, _ args: CVarArgType...) -> ObjectQuery<T> {
+        
+        return self.WHERE(NSPredicate(format: format, arguments: getVaList(args)))
+    }
+    
+    public func WHERE(format: String, argumentArray: [AnyObject]?) -> ObjectQuery<T> {
+        
+        return self.WHERE(NSPredicate(format: format, argumentArray: argumentArray))
+    }
+    
+    public func WHERE(attributeName: AttributeName, isEqualTo value: NSObject?) -> ObjectQuery<T> {
+        
+        return self.WHERE(value == nil
+            ? NSPredicate(format: "\(attributeName) == nil")!
+            : NSPredicate(format: "\(attributeName) == %@", value!)!)
+    }
+    
+    public func SORTEDBY(order: [SortOrder]) -> ObjectQuery<T> {
+        
+        if self.sortDescriptors != nil {
+            
+            HardcoreData.log(.Warning, message: "Attempted to set a Query's SORTEDBY clause more than once. The last sort order set will be used.")
+        }
+        self.sortDescriptors = order.map { sortOrder in
+            
+            switch sortOrder {
+                
+            case .Ascending(let attributeName):
+                return NSSortDescriptor(
+                    key: NSStringFromSelector(attributeName),
+                    ascending: true)
+                
+            case .Descending(let attributeName):
+                return NSSortDescriptor(
+                    key: NSStringFromSelector(attributeName),
+                    ascending: false)
+            }
+        }
+        return self
+    }
+    
+    public func SORTEDBY(order: SortOrder, _ subOrder: SortOrder...) -> ObjectQuery<T> {
+        
+        return self.SORTEDBY([order] + subOrder)
+    }
+    
+    // MARK: Internal
+    
+    internal init(entity: T.Type) {
+        
+        self.entity = entity
+    }
+    
+    internal func createFetchRequestForContext(context: NSManagedObjectContext) -> NSFetchRequest {
+        
+        let fetchRequest = NSFetchRequest()
+        fetchRequest.entity = NSEntityDescription.entityForName(
+            self.entityName,
+            inManagedObjectContext: context)
+        fetchRequest.predicate = self.predicate
+        fetchRequest.sortDescriptors = self.sortDescriptors
+        
+        return fetchRequest
+    }
+    
+    
+    // MARK: Private
+    private let entity: T.Type
+    private var predicate: NSPredicate?
+    private var sortDescriptors: [NSSortDescriptor]?
+}