Combination with Core Data

[LiborZ]

Is it possible to combine this great object mapping library with Core Data? How should swift class look like? Thanks

[Anviking]

Haven't used Core Data in a long, long time, but could something like this work?

class Test: NSManagedObject {
    @NSManaged var foo: String

    static func decode(json: AnyObject) throws -> Self {
        let test = self.init()
        test.foo = try json => "test"
    }
}

[Anviking]

Though perhaps your question was on Core Data-best-practice, and if so, I do not know.

[KingOfBrian]

I think the problem is that you can't just call self.init() on an NSManagedObject subclass, you have to call NSEntityDescription.insertNewObjectForEntityForName("MyMO", inManagedObjectContext:context). Passing in the initial context is the ugly part. Some thread local global storage is the only method that I can think of that would work. Once you are in a Managed Object class, you can refer to self.managedObjectContext though.

Any thoughts on another approach? I have a feeling that a curried generic function on NSManagedObjectContext might be able to work, but I'm not sure.

[LiborZ]

I am thinking about something like this:

class Article: NSManagedObject {

  override init(entity: NSEntityDescription, insertIntoManagedObjectContext context: NSManagedObjectContext?) {
    super.init(entity: entity, insertIntoManagedObjectContext: context)
  }

  init(inManagedObjectContext context: NSManagedObjectContext) {
    let entity = NSEntityDescription.entityForName("Article", inManagedObjectContext: context)!
    super.init(entity: entity, insertIntoManagedObjectContext: context)
  }

  static func decode(json: AnyObject, inManagedObjectContext context: NSManagedObjectContext) throws -> Article {
    let article = Article(inManagedObjectContext: context)
    article.foo = try json => "test"
  }
}

I am not sure if it is good aproach. If the init methods could be place to NSManagedObject extension then I think this would be really great.

[KingOfBrian]

A larger problem with CoreData / reference types, is you usually don't want to create new objects every import, but you want to update the state of the existing objects. This would require a proxy / generic import object probably that would contain the existing set of objects, and look them up via some defined primary key. Also, because decode is a class method there would be no pre-defined way to apply a decode to an instance.

I think this may be the end of the line for my Core Data investigation here, but I may take a stab at something. Not sure, but this may be outside of the scope of this project.