Instantiation of class in controller action not mapping post data for array of ints

Question

Using EF Core, C# .net 6 generic API setup, client is SPA.

I'm trying to instantiate some post data into a strongly-typed object:

public IActionResult Submit(MyModel model)

What the client sends:

gameIds: [9, 8, 7, 18, 17, 6, 5, 14, 12]

What the server gets (inspecting generic received object):

{[gameIds, {[9,8,7,18,17,6,5,14,12]}]}

In the populated model:

GameIds Count = 0   System.Collections.Generic.List<int>

All of my other properties automatically map correctly: ints, strings, etc.

I have a bit of an odd setup (to me anyhow) trying to get a list of Ids from a many-many foreign entity relationship when available, or just storing a List<int> for use in the service saving this off when it's a new record.

The model class itself:

private List<int> _gameIds;
[NotMapped]
public List<int> GameIds { 
    get { return (_gameIds?.Count == 0 ? Games?.Select(x => x.Id)?.ToList() : _gameIds) ?? new List<int>(); }
    set { _gameIds = value; }
}
public List<GameModel> Games { get; set; }

I'm not sure if my GameIds declaration is messing things up, or if it's something I'm missing in the instantiation, or if my approach is just wrong in general.

Answer 1

If you review in details your get part of property, written in a less compact form:

List<int> list = null;

if (_gameIds != null && _gameIds.Count == 0)
   list = Games?.Select(x => x.Id)?.ToList();
else
   list = _gameIds;

return list ?? new List<int>();

In case in which _gameIds == null, you return the else part, that is null, and return a new empty list. I prefer don't compact a lot because is more readable:

   get
   {
      var list = _gameIds != null && _gameIds.Count == 0 ? 
         Games?.Select(x => x.Id)?.ToList() : 
         _gameIds;

      return list ?? new List<int>();
   }