Resolved: Weird issue with assigning a Managed Object to another via relationship with two different instances of the same EntityDescription

Source/Categories/NSManagedObject+MagicalDataImport.m

@@ -89,13 +89,14 @@ NSString * const kMagicalRecordImportRelationshipTypeKey = @"type";
 //    NSDictionary *subentities = [originalDestinationEntity subentitiesByName];
     
     NSEntityDescription *destinationEntity = originalDestinationEntity;
-    NSDictionary *relationshipUserInfo = [relationshipInfo userInfo];
-    NSString *mappedEntityName = [relationshipUserInfo valueForKey:kMagicalRecordImportRelationshipTypeKey];
     
-    if (mappedEntityName) 
-    {
-        destinationEntity = [NSEntityDescription entityForName:mappedEntityName inManagedObjectContext:[self managedObjectContext]];
-    }
+//    NSDictionary *relationshipUserInfo = [relationshipInfo userInfo];
+//    NSString *mappedEntityName = [relationshipUserInfo valueForKey:kMagicalRecordImportRelationshipTypeKey];
+//    
+//    if (mappedEntityName) 
+//    {
+//        destinationEntity = [NSEntityDescription entityForName:mappedEntityName inManagedObjectContext:[self managedObjectContext]];
+//    }
 //    else if ([originalDestinationEntity isAbstract] && [subentities count]) 
 //    {
 //    }
@@ -120,10 +121,15 @@ NSString * const kMagicalRecordImportRelationshipTypeKey = @"type";
     {
         id lookupValue = [singleRelatedObjectData valueForKey:lookupKey];
         
-        Class managedObjectClass = NSClassFromString([destinationEntity managedObjectClassName]);
-        id existingObject = lookupValue ? [managedObjectClass findFirstByAttribute:primaryKeyName withValue:lookupValue inContext:[self managedObjectContext]] : nil;
-
-        return existingObject ?: [self MR_createInstanceForEntity:destinationEntity withDictionary:singleRelatedObjectData];
+        if (lookupValue) 
+        {
+            Class managedObjectClass = NSClassFromString([destinationEntity managedObjectClassName]);
+            NSFetchRequest *request = [managedObjectClass requestFirstByAttribute:primaryKeyName withValue:lookupValue inContext:[self managedObjectContext]];
+            [request setEntity:destinationEntity];
+            
+            id existingObject  = [managedObjectClass executeFetchRequestAndReturnFirstObject:request inContext:[self managedObjectContext]];
+            return existingObject ?: [self MR_createInstanceForEntity:destinationEntity withDictionary:singleRelatedObjectData];
+        }
     }
     return [self MR_createInstanceForEntity:destinationEntity withDictionary:singleRelatedObjectData];
 }
@@ -131,8 +137,8 @@ NSString * const kMagicalRecordImportRelationshipTypeKey = @"type";
 - (void) MR_addObject:(NSManagedObject *)relatedObject forRelationship:(NSRelationshipDescription *)relationshipInfo
 {
     NSAssert2(relatedObject != nil, @"Cannot add nil to %@ for attribute %@", NSStringFromClass([self class]), [relationshipInfo name]);    
-    NSAssert([[relatedObject entity] isEqual:[relationshipInfo destinationEntity]], @"related object not defined with same entity as destination");
-    
+    NSAssert2([relatedObject entity] == [relationshipInfo destinationEntity], @"related object entity %@ not same as destination entity %@", [relatedObject entity], [relationshipInfo destinationEntity]);
+
     //add related object to set
     NSString *addRelationMessageFormat = [relationshipInfo isToMany] ? @"add%@Object:" : @"set%@:";
     NSString *addRelatedObjectToSetMessage = [NSString stringWithFormat:addRelationMessageFormat, attributeNameFromString([relationshipInfo name])];
@@ -209,4 +215,9 @@ NSString * const kMagicalRecordImportRelationshipTypeKey = @"type";
     return [self MR_importFromDictionary:data inContext:[NSManagedObjectContext defaultContext]];
 }
 
++ (id) MR_updateFromDictionary:(NSDictionary *)data
+{
+    return [self MR_importFromDictionary:data inContext:[NSManagedObjectContext defaultContext]];    
+}
+
 @end

Source/Categories/NSManagedObject+MagicalRecord.h

@@ -16,6 +16,10 @@
 
 + (NSArray *) executeFetchRequest:(NSFetchRequest *)request;
 + (NSArray *) executeFetchRequest:(NSFetchRequest *)request inContext:(NSManagedObjectContext *)context;
++ (id) executeFetchRequestAndReturnFirstObject:(NSFetchRequest *)request;
++ (id) executeFetchRequestAndReturnFirstObject:(NSFetchRequest *)request inContext:(NSManagedObjectContext *)context;
+
+
 + (NSFetchRequest *)createFetchRequest;
 + (NSFetchRequest *)createFetchRequestInContext:(NSManagedObjectContext *)context;
 + (NSEntityDescription *)entityDescription;

Unit Tests/ImportSingleEntityRelatedToMappedEntityUsingDefaultsTests.m

@@ -23,7 +23,7 @@
     NSManagedObjectContext *context = [NSManagedObjectContext defaultContext];
     
     MappedEntity *testMappedEntity = [MappedEntity createInContext:context];
-    testMappedEntity.testMappedEntityIDValue = 42;
+    testMappedEntity.mappedEntityIDValue = 42;
     testMappedEntity.sampleAttribute = @"This attribute created as part of the test case setup";
     
     [context save];
@@ -48,7 +48,9 @@
 
 - (void) testImportMappedEntityViaToOneRelationship
 {
+    id testRelatedEntity = testEntity.mappedEntity;
     
+    assertThat(testRelatedEntity, is(notNilValue()));
 }
 
 @end

Unit Tests/ImportSingleEntityRelatedToMappedEntityUsingMappedPrimaryKeyTests.m

@@ -57,7 +57,7 @@
     assertThat([[testRelationship userInfo] valueForKey:kMagicalRecordImportRelationshipMapKey], is(equalTo(@"someRandomAttributeName")));
     
     assertThat(testRelatedEntity, is(notNilValue()));
-    assertThat([testRelatedEntity sampleAttribute], is(containsString(@"test case")));    
+    assertThat([testRelatedEntity sampleAttribute], is(containsString(@"sample json file")));    
 }
 
 - (void) testImportMappedEntityUsingPrimaryRelationshipKey
@@ -69,9 +69,9 @@
     NSRelationshipDescription *testRelationship = [[mappedEntity propertiesByName] valueForKey:@"mappedEntity"];
     assertThat([[testRelationship userInfo] valueForKey:kMagicalRecordImportRelationshipPrimaryKey], is(equalTo(@"testMappedEntityID")));
     
-    //    assertThat(testRelatedEntity, is(equalTo(testMappedEntity)));
+
     assertThat([testRelatedEntity testMappedEntityID], is(equalToInteger(42)));
-    assertThat([testRelatedEntity sampleAttribute], containsString(@"test case setup"));
+    assertThat([testRelatedEntity sampleAttribute], containsString(@"sample json file"));
 }
 
 @end