Throw an error if mappings don't match property keys

Mantle/MTLJSONAdapter.h

@@ -63,6 +63,10 @@ extern const NSInteger MTLJSONAdapterErrorNoClassFound;
 // The provided JSONDictionary is not valid.
 extern const NSInteger MTLJSONAdapterErrorInvalidJSONDictionary;
 
+// The model's implementation of +JSONKeyPathsByPropertyKey included a key which
+// does not actually exist in +propertyKeys.
+extern const NSInteger MTLJSONAdapterErrorInvalidJSONMapping;
+
 // Converts a MTLModel object to and from a JSON dictionary.
 @interface MTLJSONAdapter : NSObject
 

Mantle/MTLJSONAdapter.m

@@ -13,6 +13,7 @@
 NSString * const MTLJSONAdapterErrorDomain = @"MTLJSONAdapterErrorDomain";
 const NSInteger MTLJSONAdapterErrorNoClassFound = 2;
 const NSInteger MTLJSONAdapterErrorInvalidJSONDictionary = 3;
+const NSInteger MTLJSONAdapterErrorInvalidJSONMapping = 4;
 
 // An exception was thrown and caught.
 const NSInteger MTLJSONAdapterErrorExceptionThrown = 1;
@@ -102,7 +103,24 @@ - (id)initWithJSONDictionary:(NSDictionary *)JSONDictionary modelClass:(Class)mo
 
 	NSMutableDictionary *dictionaryValue = [[NSMutableDictionary alloc] initWithCapacity:JSONDictionary.count];
 
-	for (NSString *propertyKey in [self.modelClass propertyKeys]) {
+	NSSet *propertyKeys = [self.modelClass propertyKeys];
+
+	for (NSString *JSONKeyPath in self.JSONKeyPathsByPropertyKey.allKeys) {
+		if ([propertyKeys containsObject:JSONKeyPath]) continue;
+
+		if (error != NULL) {
+			NSDictionary *userInfo = @{
+				NSLocalizedDescriptionKey: NSLocalizedString(@"Invalid JSON mapping", nil),
+				NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%1$@ could not be parsed because its JSON mapping contains illegal property keys.", nil), modelClass]
+			};
+
+			*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONMapping userInfo:userInfo];
+		}
+
+		return nil;
+	}
+
+	for (NSString *propertyKey in propertyKeys) {
 		NSString *JSONKeyPath = [self JSONKeyPathForPropertyKey:propertyKey];
 		if (JSONKeyPath == nil) continue;
 

Mantle/MTLManagedObjectAdapter.h

@@ -150,6 +150,10 @@ extern const NSInteger MTLManagedObjectAdapterErrorUniqueFetchRequestFailed;
 // NSArray or NSSet of MTLModel<MTLManagedObjectSerializing> instances.
 extern const NSInteger MTLManagedObjectAdapterErrorUnsupportedRelationshipClass;
 
+// The model's implementation of +managedObjectKeysByPropertyKey included a key
+// which does not actually exist in +propertyKeys.
+extern const NSInteger MTLManagedObjectAdapterErrorInvalidManagedObjectMapping;
+
 // Converts a MTLModel object to and from an NSManagedObject.
 @interface MTLManagedObjectAdapter : NSObject
 

Mantle/MTLManagedObjectAdapter.m

@@ -19,6 +19,7 @@
 const NSInteger MTLManagedObjectAdapterErrorUnsupportedManagedObjectPropertyType = 5;
 const NSInteger MTLManagedObjectAdapterErrorUnsupportedRelationshipClass = 6;
 const NSInteger MTLManagedObjectAdapterErrorUniqueFetchRequestFailed = 7;
+const NSInteger MTLManagedObjectAdapterErrorInvalidManagedObjectMapping = 8;
 
 // Performs the given block in the context's queue, if it has one.
 static id performInContext(NSManagedObjectContext *context, id (^block)(void)) {
@@ -250,6 +251,23 @@ - (id)modelFromManagedObject:(NSManagedObject *)managedObject processedObjects:(
 }
 
 + (id)modelOfClass:(Class)modelClass fromManagedObject:(NSManagedObject *)managedObject error:(NSError **)error {
+	NSSet *propertyKeys = [modelClass propertyKeys];
+
+	for (NSString *mappedPropertyKey in [modelClass managedObjectKeysByPropertyKey].allKeys) {
+		if ([propertyKeys containsObject:mappedPropertyKey]) continue;
+
+		if (error != NULL) {
+			NSDictionary *userInfo = @{
+				NSLocalizedDescriptionKey: NSLocalizedString(@"Invalid entity attribute mapping", nil),
+				NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%1$@ could not be parsed because its entity attribute mapping contains illegal property keys.", nil), modelClass]
+			};
+
+			*error = [NSError errorWithDomain:MTLManagedObjectAdapterErrorDomain code:MTLManagedObjectAdapterErrorInvalidManagedObjectMapping userInfo:userInfo];
+		}
+
+		return nil;
+	}
+
 	CFMutableDictionaryRef processedObjects = CFDictionaryCreateMutable(NULL, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
 	if (processedObjects == NULL) return nil;
 

MantleTests/MTLCoreDataTestModels.h

@@ -54,3 +54,6 @@
 
 @end
 
+// Maps a non-existant property "name" to the "string" attribute.
+@interface MTLIllegalManagedObjectMappingModel : MTLModel <MTLManagedObjectSerializing>
+@end

MantleTests/MTLCoreDataTestModels.m

@@ -105,3 +105,17 @@ + (NSString *)managedObjectEntityName {
 }
 
 @end
+
+@implementation MTLIllegalManagedObjectMappingModel
+
++ (NSString *)managedObjectEntityName {
+	return @"Parent";
+}
+
++ (NSDictionary *)managedObjectKeysByPropertyKey {
+	return @{
+		@"name": @"username"
+	};
+}
+
+@end

MantleTests/MTLJSONAdapterSpec.m

@@ -88,6 +88,19 @@
 	expect(error.code).to.equal(MTLJSONAdapterErrorInvalidJSONDictionary);
 });
 
+it(@"should return nil and error with an illegal JSON mapping", ^{
+	NSDictionary *values = @{
+		@"username": @"foo"
+	};
+
+	NSError *error = nil;
+	MTLIllegalJSONMappingModel *model = [MTLJSONAdapter modelOfClass:MTLIllegalJSONMappingModel.class fromJSONDictionary:values error:&error];
+	expect(model).beNil();
+	expect(error).notTo.beNil();
+	expect(error.domain).to.equal(MTLJSONAdapterErrorDomain);
+	expect(error.code).to.equal(MTLJSONAdapterErrorInvalidJSONMapping);
+});
+
 it(@"should support key paths across arrays", ^{
 	NSDictionary *values = @{
 		@"users": @[

MantleTests/MTLManagedObjectAdapterSpec.m

@@ -226,6 +226,20 @@
 			expect(error).notTo.beNil();
 		});
 
+		it(@"should return nil and error with an illegal JSON mapping", ^{
+			MTLParent *parent = [MTLParent insertInManagedObjectContext:context];
+			expect(parent).notTo.beNil();
+
+			parent.string = @"foobar";
+
+			NSError *error = nil;
+			MTLIllegalManagedObjectMappingModel *model = [MTLManagedObjectAdapter modelOfClass:MTLIllegalManagedObjectMappingModel.class fromManagedObject:parent error:&error];
+			expect(model).beNil();
+			expect(error).notTo.beNil();
+			expect(error.domain).to.equal(MTLManagedObjectAdapterErrorDomain);
+			expect(error.code).to.equal(MTLManagedObjectAdapterErrorInvalidManagedObjectMapping);
+		});
+
 		it(@"should return an error if model doesn't validate for insert", ^{
 			MTLParentIncorrectTestModel *parentModel = [MTLParentIncorrectTestModel modelWithDictionary:@{} error:NULL];
 

MantleTests/MTLTestModel.h

@@ -62,3 +62,7 @@ extern const NSInteger MTLTestModelNameMissing;
 // Returns a default name of 'foobar' when validateName:error: is invoked
 @interface MTLSelfValidatingModel : MTLValidationModel
 @end
+
+// Maps a non-existant property "name" to the "username" key in JSON.
+@interface MTLIllegalJSONMappingModel : MTLModel <MTLJSONSerializing>
+@end

MantleTests/MTLTestModel.m

@@ -172,3 +172,13 @@ - (BOOL)validateName:(NSString **)name error:(NSError **)error {
 }
 
 @end
+
+@implementation MTLIllegalJSONMappingModel
+
++ (NSDictionary *)JSONKeyPathsByPropertyKey {
+	return @{
+		@"name": @"username"
+	};
+}
+
+@end