SQLAlchemy - MySQL - Check if row exists in existing table

Question

I have simple setup with SQLAlchemy currently it's setup to connect with existing database like this:

self.users = db.Table('users', self.metadata, autoload=True, autoload_with=self.engine)

It connects to existing table, but I don't know how to check for existing row when I connect to table when it's not created by SQLAlchemy.

What I've tried:

session.query(self.users.query.filter(self.users.id == 1).exists()).scalar()

I got that Table object doesn't have attribute query

score 0 · Answer 1 · answered Jul 05 '20 at 11:45

0

Your error means the Table object does not have a query attribute because SQLAlchemy has an separate Query API.

See this post How to query a table, in sqlalchemy

answered Jul 05 '20 at 11:45

Musab Guma'a

175
2
9

It's an existing table without base and that answer is from 2010 – poyojid682 Jul 05 '20 at 11:46

score 0 · Answer 2 · answered Jul 05 '20 at 11:57

Alright for everybody wondering solution is following:

Option

 check_existing = self.users.select().where(self.users.c.username == "admin")
 check_existing_result = session.execute(check_existing).fetchall()

 if len(check_existing_result) == 0:
     print('empty')
 else:
     print('found')

Option

 query = session.query(self.users).all()

 for obj in query:
     if obj[1] == 'admin':
         print('true')

Option

 check_existing = self.users.select().where(self.users.c.username == "admin")
 check_existing_result = session.execute(check_existing).scalar()

     if check_existing_result == None:
         print('empty')
     else:
         print('true')

Thanks to Executing a sqlalchemy exists query

SQLAlchemy - MySQL - Check if row exists in existing table

2 Answers2