Xamarin方法的Newtonsoft Json和System.ObjectDisposedException

Question

I have a list of object that I save as a json file like this:

List<Sede> listSede;
string json = JsonConvert.SerializeObject(listSede);
System.IO.File.WriteAllText(pathToJson+"\filiali.json",json);

Then I read them with this:

StreamReader r = new StreamReader (pathToJson + fileName);  
string jsonread = r.ReadToEnd();
List<Sede> items = new List<Sede> ();
items = JsonConvert.DeserializeObject<List<Sede>>(jsonread);

Class Sede inherit from MKAnnotation and after i get the list of object in items for each one of them I try to add an annotation to a map like this:

foreach (Sede c in items)
                map.AddAnnotation (c);

but it doesn't add any annotation, if I try to inspect the element c I see that there are some field that are not initialized and have an objectDisposedException, here is the image:

Answer 1

MKAnnotation is not serializable, so your class that inherits from it is not being completely inflated when you deserialize it.

You could try writing your own JsonConverter that properly handles Sede, or you could do something like this:

foreach (Sede c in items) {

  // add a constructor to Sede that properly creates a new object based on a partially inflated one  
  Sede cc = new Sede(c);

  map.AddAnnotation (cc);
}