Issue with updating Realm objects

Question

I have two Realm model classes

class ModelA: Object {
    let id = RealmOptional<Int>()
    dynamic var name: String!
    // some other variables that are also String! type
}

class ModelB: Object {
    let id = RealmOptional<Int>()
    let models = List<ModelA>()
    // other variables
}

And I have some JSON object which contains data for that models. I create ModelB instance then populate it with ModelA instances list the following way:

let json: JSON = ... // get it from somewhere, then use SwiftyJSON
let myModelB = ModelB()
myModelB.id.value = json["id"].object as? Int
// set other properties
let modelsA = json["models"].map { ModelA(value: $0.1.object) }
myModelB.models.appendContentsOf(modelsA)

The reason why I am using different approaches here is that propery names in JSON doesn't match to my property names for ModelB but for ModelA it is ok. Somewhere later I use realm.add(objects, update: true) (inside realm.write) and that leads to the following exception:

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ valueForUndefinedKey:]: this class is not key value coding-compliant for the key (null).'

According to the documentation:

If your model class includes a primary key, you can have Realm intelligently update or add objects based off of their primary key values using Realm().add(_:update:).

so both ModelA and ModelB has primaryKey() function and I believe that should work but it is not.

Furthermore, I removed update parameter in the call and added call to the realm.deleteAll() before adding new objects (both in write callback). In that case I get the following exception:

Terminating app due to uncaught exception 'RLMException', reason: 'Can't set primary key property 'id' to existing value 'xxxxxxx'.

Additionally if I try to go through the call stack, Xcode crashes. It also crashes if I try to inspect any Realm object in the debugger. I already have installed Realm Xcode plugin but nothing changes. I cannot understand what is going wrong here and why I get so strange behavior. Could someone tell me where is my mistake please?

can you show the code you used to create the realm objects you want to add as well as the modelA itself? Looks like there might be a problem there. — Kalzem

Gralex Gralex · Accepted Answer · 2016-01-26T19:33:06

I start project from scratch, base on example project. So I finished with:

import UIKit
import RealmSwift

// Dog model
class Dog: Object {
    dynamic var name = ""
    dynamic var age = 0
    dynamic var owner: Person? // Properties can be optional

    override class func primaryKey() -> String? { return "name" }
}

// Person model
class Person: Object {
    dynamic var name = ""
    let dogs = List<Dog>()

    override class func primaryKey() -> String? { return "name" }
}

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        // Override point for customization after application launch.

        do {
            try NSFileManager.defaultManager().removeItemAtPath(Realm.Configuration.defaultConfiguration.path!)
        } catch {}

        let dogRexJSON: AnyObject = ["name": "Rex", "age" : 20]
        let dogLuckyJSON: AnyObject = ["name": "Lucky", "age" : 25]
        var somePerson = Person(value: ["name" : "Shurik", "dogs" : [dogRexJSON]])


        // Realms are used to group data together
        let realm = try! Realm() // Create realm pointing to default file

        // Save your object
        realm.beginWrite()
        realm.add(somePerson)
        try! realm.commitWrite()

        somePerson = Person(value: ["name" : "Shurik", "dogs" : [dogRexJSON, dogLuckyJSON]])
        try! realm.write { () -> Void in
            realm.add([somePerson], update: true)
            return
        }

        let val = realm.objectForPrimaryKey(Dog.self, key: "Lucky")
        print(val!.name) // as expected log >> Lucky

        return true
    }
}

Seems all works fine.

Issue with updating Realm objects

1 Answers