C# how to use generic constraint with interface

Question

Can anyone help me what am i doing wrong with the following c# code? I am basically trying to add the constraint to ICommandHandler.

public interface ICommand<T> where T : BaseDto{ }

public abstract class BaseCommand<T> : ICommand<T> where T : BaseDto { }

public class CreateAlertCommand : BaseCommand<AlertDto>{}   

public interface ICommandHandler<TCommand> where TCommand : ICommand{}

I am getting error when defining ICommandHandler. It says 'Using the generic type ICommand<T> requires 1 type argument'

You don't have an ICommand type. You have an ICommand<T> type. If you want a non-generic ICommand type, you have to create one. — itsme86
– itsme86, Commented Mar 26, 2018 at 15:10
Just a small and unrelated note, class name, "CreateAlertCommand" should be just "AlertCommand" as class name should be noun and not verbs. — Yogee
– Yogee, Commented Mar 26, 2018 at 15:26
@Yogee Classes can represent verbs in which case the naming is correct. This seems appropriate in this case as the ...Command classes represent commands, which are necessarily verbs. — Dai
– Dai, Commented Mar 26, 2018 at 15:34
@dai , you are right. If "CreateAlert" is a command, the name is correct. — Yogee
– Yogee, Commented Mar 27, 2018 at 15:42

Dai · Accepted Answer · 2018-03-26 15:12:36Z

4

public interface ICommandHandler<TCommand>
    where TCommand : ICommand
{
}

Should be:

public interface ICommandHandler<TCommand,TDto>
    where TCommand : ICommand<TDto>
    where TDto : BaseDto
{
}

answered Mar 26, 2018 at 15:12

Dai

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1 Comment

Mukil Deepthi Over a year ago

Thank you so much. This is awesome.

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