模型不更新数据库

Question

For some reason the method dbase.SaveChanges() can't update the database because roomid should be null. But the debugger does say that room1.id is set to 2?

Can somebody please help me with this ?

private void button1_Click(object sender, EventArgs e)
{
    Room room1 = new Room();
    room1.Id = 2;
    dbase.AddToRoom(room1);
    dbase.SaveChanges();
}

Answer 1

i'm not sure this is actually ADO.NET, it seems more like entity framework or linq to SQL.

It's also not quite clear what you're trying to do. If you are trying to add a new Room to the database, i would advise setting some properties, otherwise you are just inserting an empty room.

var room1 = new Room();
room1.RoomNumber = 4;
room1.Available = true;
//...
dbase.AddToRoom(room1);
dbase.SaveChanges();

If this is what you are trying to do, then you do not need to specify the ID for the room (if the ID column is set to auto-increment that is.)

if you are trying to update a room instead of inserting a new one you can do something like this:

var roomToUpdate = dbase.Rooms.Where(x => x.id == id).FirstOrDefault();
roomToUpdate.Property ="something";
//...
dbase.Update(roomToUpdate)
dbase.SaveChanges();

Again, its not entirely clear what exactly you are trying to do so if i'm wrong, please elaborate a little more.