Binding data to nested property with possibly zero parent

Question

I want to bind data to Room.ToNorth.ImageNamewhile it ToNorthcan be null.

I am trying to write my own text adventure, and I have images next to each of the directions that the player can go (i.e. open / close door, path). When there is no space in the indicated direction, I have controls related to the display of the “no way out” image, this works fine as long as the player’s initial location has an exit in all 4 directions, however, when one of them is zero, I get the following exception

System.ArgumentNullException: 'The value cannot be null. Parameter Name: component '

This is not a problem for a new game, but I create randomly generated dungeons, so this cannot be guaranteed in a loaded game. I understand that I can possibly invent this by creating a safe space while the bindings are established, and then moving the player to where he should be, but is there a right way to handle this?

The closest answer I found is the question , but I'm not sure I can apply it here because of how it is connected.

private GameSession _CurrentGame;
private BindingSource _BindToPlayer = new BindingSource();

private void BtnNewGame_Click(object sender, EventArgs e)
{
    _CurrentGame = new GameSession();

    _BindToPlayer.DataSource = _CurrentGame.CurrentPlayer;

    PicBoxNorth.DataBindings.Add("ImageLocation", _BindToPlayer, 
        "CurrentRoom.ToNorth.ImageName", true, DataSourceUpdateMode.OnPropertyChanged, 
        "Images\\Wall.png");
}

ToNorth , , ( ), , , . ,

public Class Room
{
   public int ID { get; set; }
    public String Name { get; set; }
    public String Description { get; set; }
    public String FarDescription { get; set; }
    public CoOrds Co_Ords { get; set; }

    public Boolean UniqueRoom { get; set; }

    public Exit[] ExitArr { get; set; }

    public Exit ToNorth => ExitArr[0];
    public Exit ToSouth => ExitArr[1];
    public Exit ToWest => ExitArr[2];
    public Exit ToEast => ExitArr[3];
    public Exit ToUp => ExitArr[4];
    public Exit ToDown => ExitArr[5];

    public Exit ToIn => ExitArr[6];
    public Exit ToOut => ExitArr[7];

    public Room(int id, String name, String desc, String fardesc,bool unique = false)
    {
        ID = id;
        Name = name;
        Description = desc;
        FarDescription = fardesc;
        Co_Ords = new CoOrds();
        ExitArr = new Exit[8];

        UniqueRoom = unique;

    }

public class Exit
{
    public String Description {get;}         

    public Room RoomA { get; set; }
    public Room RoomB { get; set; }

    public Boolean CanExitA { get; set; } = true;
    public Boolean CanExitB { get; set; } = true;

    public Room NextRoom
    {
        get
        {

            if (RoomA.PlayerHere && CanExitA)
            { return RoomB; }
            else if (RoomB.PlayerHere && CanExitB)
            { return RoomA; }
            else
                return null;
        }
    }

    public String ImageName
    {
        get
        {
            string imagePath = "Images\\";
            if (DoorHere != null)
            {
                return imagePath + DoorHere.ImageName;
            }
            else
                return imagePath + "Pathway.png";
        }

    }

    public Door DoorHere { get; set; }

    public Exit(Room roomA, int Adir, Room roomB, int Bdir, Door door = null)
    {
        RoomA = roomA;
        RoomA.ExitArr[Adir] = this;
        RoomB = roomB;
        RoomB.ExitArr[Bdir] = this;
        DoorHere = door;

    }

Door - bool IsOpen, IsLocked .., , , Exit , .

.

Answer 1

/ .

, ToNorthImageName, / ToNorth.ImageName Room:

public string ToNorthImageName
{
    get { return ToNorth?.ImageName }
    //set { if (ToNorth != null) ToNorth.ImageName = value; }
}

, , .

:

PicBoxNorth.DataBindings.Add("ImageLocation", _BindToPlayer, "ToNorthImageName",
    true, DataSourceUpdateMode.OnPropertyChanged);