public IHttpActionResult Post(GroupViewModel groupView)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            var create = groupView.ToGroup();
            _groupService.CreateGroupAsync(create);

            return Created(MapGroupToView(create));
        }
        public IHttpActionResult Put([FromODataUri] int key, GroupViewModel groupView)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (!_groupService.GetAll().Any(g => g.GroupId == key))
            {
                return BadRequest();
            }

            var update = groupView.ToGroup();
            _groupService.UpdateGroupAsync(update);

            return Updated(MapGroupToView(update));
        }