Linq output as an Interface? - linq

Question

Here's the code that I'm attempting to do:
public IList<IOperator> GetAll()
{
using (var c = new MyDataContext())
{
return c.Operators.ToList();
}
}
Operator implements IOperator, but I'm getting the following compilation error:
Cannot implicitly convert type 'System.Collections.Generic.List<MyProject.Core.Operator>' to 'System.Collections.Generic.IList<MyProject.Core.Model.IOperator>'. An explicit conversion exists (are you missing a cast?)
How do I cast this to get what I need?

Answer 1

Try the Cast<>() method:
return c.Operators.Cast<IOperator>().ToList();

Answer 2

If I change the code to the following:
public IList<IOperator> GetAll()
{
using (var c = new MyDataContext())
{
var operators = (from o in c.Operators
select o).Cast<IOperator>();
return operators.ToList();
}
}
it not only compiles but actually works! Thanks for the nudges in the right direction.

Answer 3

Edit: Actually,
return (List< IOperator >)c.Operators.ToList();
would not do the trick. Sorry

Answer 4

Use ConvertAll<>
http://msdn.microsoft.com/en-us/library/kt456a2y.aspx
e.g.: In this case, TEntity must be an IBusinessUnit, but is a class, so i have the same trouble of converting List<Operator> to List<IOperator> (assuming Operator implements IOperator).
In your case, like you said, Operator doesn't impelement IOperator, but that doesn't matter - this will still work -
public static IList<IBusinessUnit> toIBusinessUnitIList(List<TEntity> items)
{
return items.ConvertAll<IBusinessUnit>(new Converter<TEntity, IBusinessUnit>(TEntityToIBuisinessUnit));
}
/// <summary>
/// Callback for List<>.ConvertAll() used above.
/// </summary>
/// <param name="md"></param>
/// <returns></returns>
private static IBusinessUnit TEntityToIBuisinessUnit(TEntity te)
{
return te; // In your case, do whatever magic you need to do to convert an Operator to an IOperator here.
}