[QuerySet] Add a method to check if a query returns any results

kylef · kylef · commit 0911b40f0873 · 2014-08-23T22:19:19.000+01:00
diff --git a/QueryKit/QuerySet.swift b/QueryKit/QuerySet.swift
@@ -170,6 +170,21 @@ public class QuerySet<T : NSManagedObject> : SequenceType, Equatable {
         return count().count
     }
 
+    // MARK: Exists
+
+    /** Returns true if the QuerySet contains any results, and false if not.
+    :note: Returns nil if the operation could not be completed.
+    */
+    public func exists() -> Bool? {
+        let result:Int? = count()
+
+        if let result = result {
+            return result > 0
+        }
+
+        return nil
+    }
+
     // MARK: Deletion
 
     /// Deletes all the objects matching the QuerySet.
diff --git a/QueryKitTests/QuerySetTests.swift b/QueryKitTests/QuerySetTests.swift
@@ -179,6 +179,18 @@ class QuerySetTests: XCTestCase {
         XCTAssertEqual(count!, 2)
     }
 
+    // MARK: Exists
+
+    func testExistsReturnsTrueWithMatchingObjects()  {
+        let qs = queryset.filter(NSPredicate(format: "name == %@", "Kyle"))
+        XCTAssertTrue(qs.exists()!)
+    }
+
+    func testExistsReturnsFalseWithNoMatchingObjects()  {
+        let qs = queryset.filter(NSPredicate(format: "name == %@", "None"))
+        XCTAssertFalse(qs.exists()!)
+    }
+
     // MARK: Deletion
 
     func testDelete() {
