public async Task Update(string userId, string ltiRequestJson)
		{
			var ltiRequestModel = FindElement(userId);

			if (ltiRequestModel == null)
			{
				ltiRequestModel = new LtiRequestModel
				{
					UserId = userId,
					Request = ltiRequestJson
				};
			}
			else
				ltiRequestModel.Request = ltiRequestJson;

			db.LtiRequests.AddOrUpdate(ltiRequestModel);
			await db.SaveChangesAsync();
		}
        public async Task Update(string userId, string ltiRequestJson)
        {
            var ltiRequestModel = FindElement(userId);

            if (ltiRequestModel == null)
            {
                ltiRequestModel = new LtiRequestModel
                {
                    UserId  = userId,
                    Request = ltiRequestJson
                };
            }
            else
            {
                ltiRequestModel.Request = ltiRequestJson;
            }

            db.LtiRequests.AddOrUpdate(ltiRequestModel);
            await db.SaveChangesAsync();
        }