C# 9 Design Pattern Samples

AddGameCommand.cs

public record AddGameCommand(string Title, DateTime ReleaseDate, TimeSpan HoursPlayed)
{
    public class AddGameCommandHandler 
    {
        // ...
        public void Handle(AddGameCommand request)
        {
            _db.Add("game", request);
        }
    }
}

AddGameCommandRecord.cs

public record AddGameCommand(string Title, DateTime ReleaseDate, TimeSpan HoursPlayed);

FindGameByTitleQuery.cs

public record FindGameResult(string Title, DateTime ReleaseDate, TimeSpan HoursPlayed); 

public record FindGameByTitleQuery(string Title)
{
    public class FindGameByTitleQueryHandler
    {
        public FindGameResult Handler(FindGameByTitleQuery request)
        {
            var game = _db.Games.SingleOrDefault(x => x.Title == request.Title);
            var result = _mapper.Map<FindGameResult>(game);

            return result;
        }
    }
}

Pet.cs

public record Pet(string Name, DateTime BirthDate);

PetMain.cs

var pet = new Pet("Martha", new DateTime(2019, 7, 18));
pet.BirthDate = DateTime.Now; // <- this will fail