public async Task <ActionResult <CampaignEntityCostDTO> > Post(CampaignEntityCostDTO entityCost)
        {
            var _entityCost = new CampaignEntityCost {
                Campaign = await _context.Campaigns.FirstOrDefaultAsync(p => p.Id == entityCost.CampaignId),
                Entity   = await _context.Entities.FirstOrDefaultAsync(p => p.Id == entityCost.EntityId),
                Cost     = entityCost.Cost
            };

            await _context.CampaignEntityCosts.AddAsync(_entityCost);

            await _context.SaveChangesAsync();

            return(CreatedAtAction(nameof(Get), new { id = _entityCost.Id }, entityCost));
        }
        public async Task <IActionResult> Put(int id, CampaignEntityCostDTO entityCost)
        {
            if (id != entityCost.Id)
            {
                return(BadRequest());
            }

            var _entityCost = await _context.CampaignEntityCosts
                              .Include(p => p.Campaign)
                              .Include(p => p.Entity)
                              .FirstOrDefaultAsync(p => p.Id == id);

            _entityCost.Campaign = await _context.Campaigns.FirstOrDefaultAsync(p => p.Id == entityCost.CampaignId);

            _entityCost.Entity = await _context.Entities.FirstOrDefaultAsync(p => p.Id == entityCost.EntityId);

            _entityCost.Cost = entityCost.Cost;

            _context.CampaignEntityCosts.Update(_entityCost);
            await _context.SaveChangesAsync();

            return(NoContent());
        }