Add support for deletion of mapped objects by predicate. closes #1109

Code/CoreData/RKEntityMapping.h

@@ -177,6 +177,17 @@
  */
 - (RKConnectionDescription *)connectionForRelationship:(id)relationshipOrName;
 
+///------------------------------------
+/// @name Flagging Objects for Deletion
+///------------------------------------
+
+/**
+ A predicate that identifies objects for the receiver's entity that are to be deleted from the local store.
+
+ This property provides support for local deletion of managed objects mapped as a 'tombstone' record from the source representation.
+ */
+@property (nonatomic, copy) NSPredicate *deletionPredicate;
+
 ///------------------------------------------
 /// @name Retrieving Default Attribute Values
 ///------------------------------------------

Code/CoreData/RKManagedObjectMappingOperationDataSource.m

@@ -18,6 +18,7 @@
 //  limitations under the License.
 //
 
+#import <objc/runtime.h>
 #import "RKManagedObjectMappingOperationDataSource.h"
 #import "RKObjectMapping.h"
 #import "RKEntityMapping.h"
@@ -34,6 +35,8 @@
 
 extern NSString * const RKObjectMappingNestingAttributeKeyName;
 
+static char kRKManagedObjectMappingOperationDataSourceAssociatedObjectKey;
+
 id RKTransformedValueWithClass(id value, Class destinationType, NSValueTransformer *dateToStringValueTransformer);
 NSArray *RKApplyNestingAttributeValueToMappings(NSString *attributeName, id value, NSArray *propertyMappings);
 
@@ -117,6 +120,58 @@ static NSDictionary *RKEntityIdentificationAttributesForEntityMappingWithReprese
     return entityIdentifierAttributes;
 }
 
+@interface RKManagedObjectDeletionOperation : NSOperation
+
+- (id)initWithManagedObjectContext:(NSManagedObjectContext *)managedObjectContext;
+- (void)addEntityMapping:(RKEntityMapping *)entityMapping;
+@end
+
+@interface RKManagedObjectDeletionOperation ()
+@property (nonatomic, strong) NSManagedObjectContext *managedObjectContext;
+@property (nonatomic, strong) NSMutableSet *entityMappings;
+@end
+
+@implementation RKManagedObjectDeletionOperation
+
+- (id)initWithManagedObjectContext:(NSManagedObjectContext *)managedObjectContext
+{
+    self = [self init];
+    if (self) {
+        self.managedObjectContext = managedObjectContext;
+        self.entityMappings = [NSMutableSet new];
+    }
+    return self;
+}
+
+- (void)addEntityMapping:(RKEntityMapping *)entityMapping
+{
+    if (! entityMapping.deletionPredicate) return;
+    [self.entityMappings addObject:entityMapping];
+}
+
+- (void)main
+{
+    [self.managedObjectContext performBlockAndWait:^{
+        NSMutableSet *objectsToDelete = [NSMutableSet set];
+        for (RKEntityMapping *entityMapping in self.entityMappings) {
+            NSFetchRequest *fetchRequest = [NSFetchRequest alloc];
+            [fetchRequest setEntity:entityMapping.entity];
+            [fetchRequest setPredicate:entityMapping.deletionPredicate];
+            NSError *error = nil;
+            NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
+            if (fetchedObjects) {
+                [objectsToDelete addObjectsFromArray:fetchedObjects];
+            }
+        }
+
+        for (NSManagedObject *managedObject in objectsToDelete) {
+            [self.managedObjectContext deleteObject:managedObject];
+        }
+    }];
+}
+
+@end
+
 // Set Logging Component
 #undef RKLogComponent
 #define RKLogComponent RKlcl_cRestKitCoreData
@@ -126,6 +181,7 @@ extern NSString * const RKObjectMappingNestingAttributeKeyName;
 @interface RKManagedObjectMappingOperationDataSource ()
 @property (nonatomic, strong, readwrite) NSManagedObjectContext *managedObjectContext;
 @property (nonatomic, strong, readwrite) id<RKManagedObjectCaching> managedObjectCache;
+@property (nonatomic, strong) NSMutableArray *deletionPredicates;
 @end
 
 @implementation RKManagedObjectMappingOperationDataSource
@@ -169,7 +225,7 @@ extern NSString * const RKObjectMappingNestingAttributeKeyName;
                       "Unable to update existing object instances by identification attributes. Duplicate objects may be created.");
     }
 
-    // If we have found the entity identifier attributes, try to find an existing instance to update
+    // If we have found the entity identification attributes, try to find an existing instance to update
     NSEntityDescription *entity = [entityMapping entity];
     NSManagedObject *managedObject = nil;
     if ([entityIdentifierAttributes count]) {
@@ -246,6 +302,27 @@ extern NSString * const RKObjectMappingNestingAttributeKeyName;
             [operationQueue addOperation:operation];
             RKLogTrace(@"Enqueued %@ dependent upon parent operation %@ to operation queue %@", operation, self.parentOperation, operationQueue);
         }
+
+        // Handle tombstone deletion by predicate
+        if ([(RKEntityMapping *)mappingOperation.objectMapping deletionPredicate]) {
+            RKManagedObjectDeletionOperation *deletionOperation = nil;
+            if (self.parentOperation) {
+                // Attach a deletion operation for execution after the parent operation completes
+                deletionOperation = (RKManagedObjectDeletionOperation *)objc_getAssociatedObject(self.parentOperation, &kRKManagedObjectMappingOperationDataSourceAssociatedObjectKey);
+                if (! deletionOperation) {
+                    deletionOperation = [[RKManagedObjectDeletionOperation alloc] initWithManagedObjectContext:self.managedObjectContext];
+                    objc_setAssociatedObject(self.parentOperation, &kRKManagedObjectMappingOperationDataSourceAssociatedObjectKey, deletionOperation, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+                    [deletionOperation addDependency:self.parentOperation];
+                    NSOperationQueue *operationQueue = self.operationQueue ?: [NSOperationQueue currentQueue];
+                    [operationQueue addOperation:deletionOperation];
+                }
+                [deletionOperation addEntityMapping:(RKEntityMapping *)mappingOperation.objectMapping];
+            } else {
+                deletionOperation = [[RKManagedObjectDeletionOperation alloc] initWithManagedObjectContext:self.managedObjectContext];
+                [deletionOperation addEntityMapping:(RKEntityMapping *)mappingOperation.objectMapping];
+                [deletionOperation start];
+            }
+        }
     }
     
     return YES;

Tests/Logic/CoreData/RKManagedObjectMappingOperationDataSourceTest.m

@@ -1064,6 +1064,50 @@
     
 }
 
+- (void)testDeletionOfTombstoneRecords
+{
+    RKManagedObjectStore *managedObjectStore = [RKTestFactory managedObjectStore];
+    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Human" inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    RKEntityMapping *mapping = [[RKEntityMapping alloc] initWithEntity:entity];
+    [mapping addAttributeMappingsFromArray:@[ @"name" ]];
+    mapping.deletionPredicate = [NSPredicate predicateWithFormat:@"sex = %@", @"female"];
+
+    RKHuman *human = [NSEntityDescription insertNewObjectForEntityForName:@"Human" inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    human.sex = @"female";
+
+    RKManagedObjectMappingOperationDataSource *dataSource = [[RKManagedObjectMappingOperationDataSource alloc] initWithManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext
+                                                                                                                                      cache:nil];
+    NSDictionary *representation = @{ @"name": @"Whatever" };
+    RKMappingOperation *operation = [[RKMappingOperation alloc] initWithSourceObject:representation destinationObject:human mapping:mapping];
+    operation.dataSource = dataSource;
+    NSError *error = nil;
+    BOOL success = [operation performMapping:&error];
+    assertThatBool(success, is(equalToBool(YES)));
+    expect([human isDeleted]).to.equal(YES);
+}
+
+- (void)testDeletionOfTombstoneRecordsInMapperOperation
+{
+    RKManagedObjectStore *managedObjectStore = [RKTestFactory managedObjectStore];
+    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Human" inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    RKEntityMapping *mapping = [[RKEntityMapping alloc] initWithEntity:entity];
+    [mapping addAttributeMappingsFromArray:@[ @"name" ]];
+    mapping.deletionPredicate = [NSPredicate predicateWithFormat:@"sex = %@", @"female"];
+
+    RKHuman *human = [NSEntityDescription insertNewObjectForEntityForName:@"Human" inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    human.sex = @"female";
+
+    RKManagedObjectMappingOperationDataSource *dataSource = [[RKManagedObjectMappingOperationDataSource alloc] initWithManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext
+                                                                                                                                      cache:nil];
+    NSDictionary *representation = @{ @"name": @"Whatever" };
+    NSError *error = nil;
+    RKMapperOperation *mapperOperation = [[RKMapperOperation alloc] initWithRepresentation:representation mappingsDictionary:@{ [NSNull null]: mapping }];
+    mapperOperation.mappingOperationDataSource = dataSource;
+    BOOL success = [mapperOperation execute:&error];
+    assertThatBool(success, is(equalToBool(YES)));
+    expect([human isDeleted]).to.equal(YES);
+}
+
 // TODO: Import bencharmk utility somehow...
 //- (void)testMappingAPayloadContainingRepeatedObjectsPerformsAcceptablyWithFetchRequestMappingCache
 //{