public async Task <bool> WatchStory(string storyId, string userId) { var story = await database.StoryRepository.FindById(storyId) ?? throw new EntityNotFoundException("Story not found"); if (story.UserStories.Any(us => us.UserId == userId)) { return(true); } var userStory = UserStory.Create(story.Id, userId); story.UserStories.Add(userStory); return(await database.Complete()); }