Question

I would like to perform a cast of something like this:

// Entity Data and Entity A_Data has exactly the same properties: sName and sZip.
List<Data> ListData = new List<Data>();
List<A_Data> ListA_Data = (A_Data)ListData.FindAll(item => item.sName.StartsWith("A"));

VS2010 keeps telling me that I cannot make this cast. Any help would be appreciated.

Answer 1

Unless a class is explicitly declared to derive from another cast, you cannot cast between them. Even if they have the same properties or fields.

class Data  { public string Name { get; set; } public string Zip { get; set; } }
class AData { public string Name { get; set; } public string Zip { get; set; } }

Data  data  = new Data { Name = "Foo", Zip = "Bar" };
AData adata = (AData)data;  // doesn't work

You need a converter method in this case:

AData ToAData(Data data)
{
    return new AData { Name = data.Name, Zip = data.Zip };
}

Not sure if there’s anything in EF4 that helps with this.