python - translate this sql into flask-sqlalchemy syntax -

i'm using flask-sqlalchemy.
here mysql:

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

how should translate sqlalchemy?

thanks 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 model.

assuming have model rssurl , rssitem, relationship rssurl.rss_items.

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