GetUserDetailHandler.cs

public class GetUserDetailHandler : IRequestHandler<GetUserDetailQuery, UserDto> 
{
   	private readonly IUserRepository _userRepository;
    private readonly IUserMapper _userMapper;
    
    public GetUserDetailHandler(IUserRepository userRepository, IUserMapper userMapper) {
    	_userRepository = userRepository ?? throw new ArgumentNullException(nameof(userRepository));
    	_userMapper = userMapper ?? throw new ArgumentNullException(nameof(userMapper));
    }
    
    public async Task<UserDto> Handle(GetUserDetailQuery request, CancellationToken cancellationToken) {
    var user = await _userRepository.GetAsync(u => u.Id == request.Id)
    
    if user == null {
    	return null
    }
    
    var userDto = _userMapper.MapUserDto(user);
    return userDto;
    }
}