How can I create a list from items in another list?
List<Post> postList = db.Posts.Where(u => u.PostId == postId).ToList();
List<PostView> viewList = db.PostViews.Where(u => u.PostId **** is equal to PostId within postList**** );
I used the ****'s to show where my understanding falls apart.
You can select the Id's from the other list, then see if that list contains your current Id. Although, I would generate the list of Id's first. Assuming your Id's are of type int:
List<Post> postList = db.Posts.Where(u => u.PostId == postId).ToList();
List<int> postIds = postList.Select(u => u.PostId).ToList();
List<PostView> viewList = db.PostViews.Where(u => postIds.Contains(u.PostId)).ToList();
postIds were a HashSet
Give this a shot:
List<PostView> viewList = db.PostViews.Where(
u => postList.Any(p => p.PostId == u.PostId));
List<PostView> viewList = db.PostViews.Where(u => postList.Any(pl=>pl.postId == u.postId));
But you should be able to do this in one shot:
List<PostView> viewList = db.PostViews.Where(u => u.Post.postId == postId);
or even
List<PostView> viewList = db.PostViews.Where(u => u.PostId == postId);
It seems a postview has a post. You shouldn't have to get a list of posts first and then get a list of views from that list.
