UserInfo can't have a ForeignKey with JupyterHub User model

[leportella]

So, I created a class called UserInfo to store extra information on the user that the default JupyterHub User class won't. The UserInfo class can be seen here.

This table (user_info) is created on the Authenticator __init__ method by the following way:
UserInfo.__table__.create(self.db) where self.db is a SQLAlchemy Engine instance.

However, when I try to add a relationship between UserInfo and User, this method won't work. Usually I get this error: NoReferencedTableError: Foreign key associated with column 'product.user_id' could not find table 'user' with which to generate a foreign key to target column 'id'

I created a simple example and the main problem that I found is that, if I create both tables at the same time (using Base.metadata.create_all(engine)) everything works fine. The problem is creating the relationship after the User table has already been created.

Since I am not changing anything on JupyterHub, the User table is always created before the moment I create the UserInfo table, so I can't change this for now.

Some things I tried on the process:

• I tried to add the relationship to the User class before the creation of the new table by using this command: User.__mapper__.add_property('products', relationship("product", collection_class=set))
• I tried using a automap_base instead of a declarative_base, then created the UserInfo table before by using self.db.execute(..SQL..) and then get the table using automap.

For now, my UserInfo is not related to User, and it only uses the same username in the momento of creation since I have no idea how to fix this.

[yuvipanda]

@minrk heya! Do you think you'll have any time to help me / @leportella out on this one? We're trying to use the same db that JupyterHub is using for the authenticator too...

[dedeco]

The tables User and UserInfo are in the same schema (in database)? Using the Base = declarative_base() the objects should share the same variable Base... Can you import and use the same variable Base of jupyterhub/jupyterhub/orm.py?

[leportella]

@dedeco I just tested it on a simple example I was working and it seems to work fine! I'll test using User and UserInfo and let you guys know! Thank you so much!

[leportella]

@dedeco , @yuvipanda it worked!

[minrk]

Sorry, didn't catch up before it looks like it was solved. Great!

I think I would probably advise strongly against custom authenticators using the private jupyterhub.orm and creating anything in the jupyterhub databases directly, though. There's absolutely no guarantee that anything there is stable for public consumption (not the tables, not the classes, not the orm module existing at all).

[leportella]

@minrk I'll open another issue to discuss this, since this is closed :)