sqlalchemy：不同表的基数相同

Question

I have different tables, that I declare in a very standard way, but with a global Base:

GlobalData.py

from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()

init()
engine= ...
Base.metadata.create_all(engine)

TableA.py

import globaldata as gd
TableA(gd.Base)
...

TableB.py

import globaldata as gd
TableB(gd.Base)
...

Problem: If I import TableA or to TableB more than once in other files, the tables will be added more than once in the metadata. Then this created conflict when I try any action on one of those tables.

---

EDIT

The issue I receive, when I try to access a table is:

Multiple classes found for path "RolloutPermission" in the registry of this declarative base. Please use a fully module-qualified path.

I assume this is a design issue, however, I don't see what is wrong with mine. Any input is welcomed

Answer 1

I also kind of did the same as you did, sort of. I only declare the base and import it everywhere, like you do, but without this code

init()   

engine=Base.metadata.create_all(engine)

I import my base then in an env file from alembic and generate migrations. If you're going to work with a slightly more complex I highly recommand migration files:).

The problem might indeed be that you basically call create_all on every import. Look into alembic, get rid of the few lines I wrote above and you'll have working code:)