public IActionResult RSVP(int userId, int campaignId, string source)
        {
            Particpant newParticpant = new Particpant()
            {
                UserId     = userId,
                CampaignId = campaignId
            };

            _context.Particpants.Add(newParticpant);
            _context.SaveChanges();
            if (source == "camp")
            {
                return(RedirectToAction("SingleCampaign", new { campaignId = campaignId }));
            }
            else
            {
                return(RedirectToAction("Dashboard"));
            }
        }