how can I ask if grid.selectedvalue is newitemplaceholder in wpf

Question

I am trying to add new record to database by linq only if is a new row from a datagrid wpf.

Answer 1

You could use is. Here is a sample example

public interface IItemType  
{  
    int x { get; set; }  
}  


public class OldItem : IItemType  
{  
    public int x { get; set; }  
}  


public class NewItem : IItemType  
{  
    public int x { get; set; }  
}  


   for(int i=0; i<10;i++)  
   {  
       if(i % 2 ==0)  
       {  
           list.Add(new OldItem { x = i });  
       }  
       else  
       {  
           list.Add(new NewItem { x = i });  
       }  
   }  

   var newItems = list.Where(itm => itm is NewItem).ToList();  

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/is