Realm errors: RLMArray and Migration - ios

Question

I ran into some errors when I'm trying to compile my realm code, this is the first version of the code:
import RealmSwift
class Test: Object {
dynamic var name = ""
dynamic var dict = Dictionary<String, Int>()
dynamic var owner: TestList?
}
class TestList: Object{
dynamic var name = ""
let tests = List<Test>().filter("ALL Test.dict[hello] != nil")
}
//ViewController
import RealmSwift
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let realm = Realm()
let test1 = Test()
test1.name = "test1"
test1.dict = ["hello": 1]
realm.write{realm.add(test1)}
let test2 = Test()
test2.name = "test2"
test2.dict = ["nihao": 2]
realm.write{realm.add(test2)}
let test3 = Test()
test3.name = "test3"
test3.dict = ["hello": 3]
realm.write{realm.add(test3)}
}
#IBOutlet weak var label: UILabel!
#IBAction func set(sender: UIButton){
let test = Test()
let realm = Realm()
test.name = "not using CoreData"
realm.write{realm.add(test)}
text = "abc"
}
#IBAction func show(sender: UIButton){
let test = Realm().objects(TestList)
var str = ""
println("got to here")
for i in test{
str += " \(i.name)"
}
label.text = str
}
}
With this setup I got an error in my log that says:
Terminating app due to uncaught exception 'RLMException', reason: 'This method can only be called on RLMArray instances retrieved from an RLMRealm'
When I removed the filtering in my TestList object, the error became: Terminating app due to uncaught exception 'RLMException', reason: 'Migration is required for object type 'Test' due to the following errors:
- Property 'dict' has been added to latest object model.
- Property 'owner' has been added to latest object model.'
Am I understanding Realm's documentation completely wrong?

Answer 1

The first error is right. You can't filter on properties. Furthermore Realm doesn't allow Dictionary properties at the moment. You would need to explicitly model that as a list property of a dedicated Realm object entity, which has fields to hold a String and an Int.
class Test: Object {
dynamic var name = ""
dynamic var dict = List<TestRelatedThing>()
dynamic var owner: TestList?
}
class TestRelatedThing : Object {
dynamic var key: String
dynamic var value: Int
}
class TestList: Object{
dynamic var name = ""
let tests = List<Test>()
}
You can then query at runtime by:
Realm().objects(TestList).filter("ANY tests.key == %#", "hello")
Hint: The aggregate operator ALL is not supported for Realm. See our predicate cheat sheet for a full list of supported operators. Here it makes anywhere more sense to existential quantify that operation, because of the changed data structure, which doesn't allow an entry of TestRelatedThing with it's value property to equal nil to exist in the first place. So you can just make sure that there is an entry with key "hello" instead.
For the second error: I guess you tried to run your code before and added after that first run further fields to your model objects.
You can reset the simulator state or might just add one of the following lines of code to ensure to start with a fresh Realm on each run while development.
# Swift 1.2
var error: NSError?
NSFileManager.defaultManager().removeItemAtPath(Realm.defaultPath, error:&error)
# Swift 2
try! NSFileManager.defaultManager().removeItemAtPath(Realm.defaultPath)