gistfile1.txt

public ActionResult AddPost(PostCommand command)
{
    var response = mediator.Send(command);
    if (response.Success) {
        return RedirectToAction("Index", "Post", new { slug = response.Data.Slug });
    }
    ModelState.AddModelError("", response.Message)
    return View(command);
}

gistfile2.txt

IMediator broker;


public ActionResult AddPost(PostCommand command)
{
    var response = broker.Send(command);
    if (response.Successful) 
    {
        var postSlug = response.Data;
        
    }
    ModelState.AddModelError("", "Slug occupied");
    return View("", command);
}