Exclude extra cross-posts from main feed #206

app/main/routes.py

@@ -116,9 +116,39 @@ def home_page(sort, view_filter):
         posts = posts.order_by(desc(Post.last_active))
 
     # Pagination
-    posts = posts.paginate(page=page, per_page=100 if current_user.is_authenticated and not low_bandwidth else 50, error_out=False)
-    next_url = url_for('main.index', page=posts.next_num, sort=sort, view_filter=view_filter) if posts.has_next else None
-    prev_url = url_for('main.index', page=posts.prev_num, sort=sort, view_filter=view_filter) if posts.has_prev and page != 1 else None
+    if view_filter == 'subscribed' and current_user.is_authenticated and sort == 'new':
+        # use python list instead of DB query
+        posts = posts.all()
+
+        # exclude extra cross-posts from feed
+        already_seen = []
+        limit = 100 if not low_bandwidth else 50
+        #i = -1                                                 # option 1: don't exclude cross-posts
+        #i = limit - 1                                          # option 2: exclude cross-posts from the first page only
+        i = (limit * 10) - 1                                    # option 3: exclude cross-posts across a 'magic number' of pages
+        #i = len(posts) - 1                                     # option 4: exclude all cross-posts ever
+        while i >= 0:
+            if not posts[i].cross_posts:
+                i -= 1
+                continue
+            if posts[i].id in already_seen:
+                posts.pop(i)
+            else:
+                already_seen.extend(posts[i].cross_posts)
+            i -= 1
+
+        # paginate manually (can't use paginate())
+        start = (page - 1) * limit
+        end = start + limit
+        posts = posts[start:end]
+        next_page = page + 1 if len(posts) == limit else None
+        previous_page = page - 1 if page != 1 else None
+        next_url = url_for('main.index', page=next_page, sort=sort, view_filter=view_filter) if next_page else None
+        prev_url = url_for('main.index', page=previous_page, sort=sort, view_filter=view_filter) if previous_page else None
+    else:
+        posts = posts.paginate(page=page, per_page=100 if current_user.is_authenticated and not low_bandwidth else 50, error_out=False)
+        next_url = url_for('main.index', page=posts.next_num, sort=sort, view_filter=view_filter) if posts.has_next else None
+        prev_url = url_for('main.index', page=posts.prev_num, sort=sort, view_filter=view_filter) if posts.has_prev and page != 1 else None
 
     # Active Communities
     active_communities = Community.query.filter_by(banned=False)