got the relationship working, and the mark_as_read working

app/models.py

@@ -699,11 +699,10 @@ class User(UserMixin, db.Model):
     roles = db.relationship('Role', secondary=user_role, lazy='dynamic', cascade="all, delete")
 
     hide_read_posts = db.Column(db.Boolean, default=False)
-    read_post = db.relationship(
-        'Post', secondary=read_posts,
-        primaryjoin=(read_posts.c.user_id == id),
-        secondaryjoin=(read_posts.c.read_post_id == id),
-        backref=db.backref('read_by', lazy='dynamic'), lazy='dynamic')
+    # db relationship tracked by the "read_posts" table
+    # this is the User side, so its referencing the Post side
+    # read_by is the corresponding Post object variable
+    read_post = db.relationship('Post', secondary=read_posts, back_populates='read_by', lazy='dynamic')
 
     def __repr__(self):
         return '<User {}_{}>'.format(self.user_name, self.id)
@@ -1031,15 +1030,15 @@ class User(UserMixin, db.Model):
             return str(e)
 
     # mark a post as 'read' for this user
-    def mark_post_as_read(self, post_id):
+    def mark_post_as_read(self, post):
         # check if its already marked as read, if not, mark it as read
-        if not self.has_read_post(post_id):
-            self.read_post.append(post_id)
+        if not self.has_read_post(post):
+            self.read_post.append(post)
 
     # check if post has been read by this user
     # returns true if the post has been read, false if not
-    def has_read_post(self, post_id):
-        return self.read_post.filter(read_posts.c.read_post_id == post_id).count() > 0
+    def has_read_post(self, post):
+        return self.read_post.filter(read_posts.c.read_post_id == post.id).count() > 0
     
 
 
@@ -1104,6 +1103,11 @@ class Post(db.Model):
     replies = db.relationship('PostReply', lazy='dynamic', backref='post')
     language = db.relationship('Language', foreign_keys=[language_id])
 
+    # db relationship tracked by the "read_posts" table
+    # this is the Post side, so its referencing the User side
+    # read_post is the corresponding User object variable
+    read_by = db.relationship('User', secondary=read_posts, back_populates='read_post', lazy='dynamic')
+
     def is_local(self):
         return self.ap_id is None or self.ap_id.startswith('https://' + current_app.config['SERVER_NAME'])
 

app/post/routes.py

@@ -247,6 +247,12 @@ def show_post(post_id: int):
     if post.type == POST_TYPE_LINK and body_has_no_archive_link(post.body_html) and url_needs_archive(post.url):
         archive_link = generate_archive_link(post.url)
 
+    # for logged in users who have the 'hide read posts' function enabled
+    # mark this post as read
+    if current_user.is_authenticated and current_user.hide_read_posts:
+        current_user.mark_post_as_read(post)
+        db.session.commit()
+
     response = render_template('post/post.html', title=post.title, post=post, is_moderator=is_moderator, is_owner=community.is_owner(),
                            community=post.community,
                            breadcrumbs=breadcrumbs, related_communities=related_communities, mods=mod_list,
@@ -330,6 +336,12 @@ def post_vote(post_id: int, vote_direction):
     cache.delete_memoized(recently_upvoted_posts, current_user.id)
     cache.delete_memoized(recently_downvoted_posts, current_user.id)
 
+    # for logged in users who have the 'hide read posts' function enabled
+    # mark this post as read
+    if current_user.is_authenticated and current_user.hide_read_posts:
+        current_user.mark_post_as_read(post)
+        db.session.commit()
+
     template = 'post/_post_voting_buttons.html' if request.args.get('style', '') == '' else 'post/_post_voting_buttons_masonry.html'
     return render_template(template, post=post, community=post.community, recently_upvoted=recently_upvoted,
                            recently_downvoted=recently_downvoted)