Entity Framework CalculatedAttribute [Mapping]

public class CustomerRow : Row
{
public string Firstname
{
get { return Fields.Firstname[this]; }
set { Fields.Firstname[this] = value; }
}
public string Lastname
{
get { return Fields.Lastname[this]; }
set { Fields.Lastname[this] = value; }
}
[Expression("(T0.[Firstname] + ' ' + T0.[Lastname])")]
public string Fullname
{
get { return Fields.Fullname[this]; }
set { Fields.Fullname[this] = value; }
}
}