SQLAlchemy & Flask - 从多表查询中获取结果

Question

Trying to find the solution that does not require adding many conditions and extra code, and haven't been able to find any resources online that tackle my specific need.

I have a web application that's going to end up being a simple forum and blog site. There will be individual users and accounts, where each user can either friend or follow other users. What is meant to happen is that when you friend and/or follow a user any status update they post is meant to show on your home screen.

However the code only shows the status of those that you are both friends with and following, not if you are only following and not friends and vice versa. The function that is returning the results is as below -

    def related_posts(self):
    shown_posts = db.session.query(Status).join(followers, followers.c.followed_id == Status.user_id).join(
        friends, friends.c.friend_id == Status.user_id).filter(
        followers.c.follower_id == self.id, friends.c.user_id == self.id)
    own_posts = Status.query.filter_by(user_id=self.id)
    return own_posts.union(shown_posts).order_by(Status.timestamp.desc())

This code is part of a User class that creates the User's table. This code references another class that holds Status' posted by Users, and two sub-tables that are created to facilitate many-to-many relationships for friend and follow functionality.

The returned results are shown in the following view -

@bp.route('/', methods=['GET', 'POST'])
@bp.route('/index', methods=['GET', 'POST'])
def index():
    form = StatusForm()
    # if request.method == 'POST' and form.submit():
    if form.validate_on_submit():
        status = Status(body=form.status.data, author=current_user)
        db.session.add(status)
        db.session.commit()
        flash('Your status has been updated!')
        return redirect(url_for('main.index'))
    user_status = Status.query.filter_by(user_id=current_user.id).order_by(Status.timestamp.desc()) if current_user.is_authenticated \
        else Status.query.order_by(Status.timestamp.desc())
    shown_posts = current_user.related_posts() if current_user.is_authenticated \
        else None
    return render_template('main/index.html', title='Welcome to the Blog!', form=form,
                           user_status=user_status, shown_posts=shown_posts)

I don't know if there is a simple way to do this and I'm just missing it, but I've read through the documentation and searched online for a solution to the issue. But what I've found so far has yet to resolve the issue. Any assistance is greatly appreciated and I hope I presented enough information here to allow that.

Answer 1

This is a very late closure for the question, but I received a great answer from Andi Schroff as a comment on the question:

Why not split up shown_posts into shown_posts_friends and shown_posts_follower? Split up the query for shown_posts into the two parts, and use a union of 3 in the return instead of 2. In your current version your are limiting the outcome to Status of users that are friends and followers.