Realm - Can't create object with existing primary key value

Question

I have a object Person with many dogs. App has separate page where it shows just dogs and other page where it shows person's dogs

My model is as follows

class Person: Object {
    dynamic var id = 0
    let dogs= List<Dog>()

    override static func primaryKey() -> String? {
        return "id"
    }
}

class Dog: Object {
    dynamic var id = 0
    dynamic var name = ""

    override static func primaryKey() -> String? {
        return "id"
    }
}

I have persons stored in Realm. Person has detail page where we fetch and show his dogs. If dog already exist, I update latest info for that dog and add it to person's dog list else create new dog, save it and add it to persons list. This works in coredata.

// Fetch and parse dogs
if let person = realm.objects(Person.self).filter("id =\(personID)").first {
    for (_, dict): (String, JSON) in response {
        // Create dog using the dict info,my custom init method
        if let dog = Dog(dict: dict) {
            try! realm.write {
                // save it to realm
                realm.create(Dog, value:dog, update: true)
                // append dog to person
                person.dogs.append(dog)
            }
        }
    }
    try! realm.write {
        // save person
        realm.create(Person.self, value: person, update: true)
    }
}

On trying to update person with his dogs,realm throws exception Can't create object with existing primary key value

Answer 1

Latest API solution:

Use add(_:update:).

try realm.write {
    realm.add(objects, update: Realm.UpdatePolicy.modified)
    // OR
    realm.add(object, update: .modified)
}

Realm.UpdatePolicy enums:

error (default)
modified //Overwrite only properties in the existing object which are different from the new values.
all //Overwrite all properties in the existing object with the new values, even if they have not changed

NB: Works on Realm Swift 3.16.1