// POST odata/ElementField
        public async Task <IHttpActionResult> Post(Delta <ElementField> patch)
        {
            var elementField = patch.GetEntity();

            // Don't allow the user to set these fields / coni2k - 29 Jul. '17
            // TODO Use ForbiddenFieldsValidator?: Currently breeze doesn't allow to post custom (delta) entity
            // TODO Or use DTO?: Needs a different metadata than the context, which can be overkill
            elementField.Id = 0;
            elementField.IndexRatingTotal = 0;
            elementField.IndexRatingCount = 0;
            elementField.CreatedOn        = DateTime.UtcNow;
            elementField.ModifiedOn       = DateTime.UtcNow;
            elementField.DeletedOn        = null;

            // Owner check: Entity must belong to the current user
            var userId = await _resourcePoolManager
                         .GetElementSet(elementField.ElementId, true, item => item.ResourcePool)
                         .Select(item => item.ResourcePool.UserId)
                         .Distinct()
                         .SingleOrDefaultAsync();

            var currentUserId = User.Identity.GetUserId <int>();

            if (currentUserId != userId)
            {
                return(StatusCode(HttpStatusCode.Forbidden));
            }

            await _resourcePoolManager.AddElementFieldAsync(elementField);

            return(Created(elementField));
        }