将此sql转换为flask-sqlalchemy语法

Question

I'm using Flask-sqlalchemy.
Here is the mysql:

select u.id, count(i.id) as count from rss_urls as u left join rss_items as i on u.id = i.rss_urls_id group by u.id;

How should I translate that into sqlalchemy?

Thanks a lot.

class RSS_urls(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    link = db.Column(db.String(200), unique=True)
    add_time = db.Column(db.DateTime)
    rss_items = db.relationship("RSS_items", backref="base_url", lazy="dynamic")


class RSS_items(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    rss_urls_id = db.Column(db.Integer, db.ForeignKey("RSS_urls.id"))
    link = db.Column(db.String(200))
    title = db.Column(db.String(200))

Here is the model.

Answer 1

Assuming you have a model RssUrl and RssItem , with a relationship RssUrl.rss_items .

db.session.query(RssUrl.id, db.func.count(RssUrl.id).label("count")
    ).join(RssUrl.rss_items).group_by(RssUrl.id)