Calling one handler from another one, is it good?

Hello all, I recently started using Mediatr in my web api project and I am pretty happy with that. But I have one issue, my web API accepts a request with following JSON data.

{
	"Title": "First note",   //Note title  
	"Details" : "Hello World",  // Note detail
	"UserId": 1 // User id who created this note
}

As u can see above the UserId is 1 which is nothing but the user with Id 1 in database. But while saving this note (about JSON object is Note object), the repository method accepts an actual User object rather than UserId. So before saving in db I need to get the user details who has Id 1 and then initialize the user property of note object with those details and then save it to the database. So I need to let u know that I already have a query that retrieves the specific user with its UserId passed to it. So my question is that can I call that query handler bypassing user id with it and then get that user and then save my note to the database? Is it good practice? I did research on it, some people used the pipeline (I don’t know much about it) to achieve it.

public class CreateNoteCommandHandler : IRequestHandler<CreateNoteCommand>
    {
        private readonly INoteRepository _noteRepository;
        private readonly IUserRepository _userRepository;

        public CreateNoteCommandHandler(INoteRepository noteRepository, IUserRepository userRepository)
        {
            _noteRepository = noteRepository;
            _userRepository = userRepository;

        }

        public Task<Unit> Handle(CreateNoteCommand request, CancellationToken cancellationToken)
        {

            // Call user repository to get that specific user 
            var user = _userRepository.Get(request.Note.UserId);

                                    // OR


            // should i inject mediator here and call corresponding method
            // OR var user _mediator.Send(new GetUserById(request.Note.UserId);

            var note = new Note
            {
                User = user,
                Details = request.Note.Details,
                Title = request.Note.Title
            };

            _noteRepository.Add(note);
            return Task.FromResult(Unit.Value);
        }
    }

I have already read this article BTW https://lostechies.com/jimmybogard/2016/12/12/dealing-with-duplication-in-mediatr-handlers/

[jbogard]

To answer your first question - we’ve done nested handlers in the past on projects, and it’s never really turned out well. The indirection of a handler is good at the application level, but just got confusing once we got inside a handler (and it introduced coupling). I’d do exactly as you show above.

A broader question though is “should I have to query the database to get a FK entity”, and these days, I prefer “no”.

In your model, I’d have two properties - UserId and User. I don’t know what your persistence strategy, but ORMs like EF can handle this just fine.

It saves a query to the database when you just want to insert something.

[nibro7778]

I agreed with @jbogard and we should avoid the mediator command handler calling another mediator command handler but it should be fine to publish the mediator single/multiple events from the same command handler. Please correct me if I am the wrong @jbogard?