I am attempting to create a revision with --autogenerate using Alembic for two Models, but am receiving a duplicate table keys error. Does, a schema need to be specified? If so, how can it be set? The documentation I've read says to use __table_args__ = {'schema': 'somename'}, but that hasn't helped. Any tips or suggestions are greatly appreciated.
My current setup is:
base.py
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
workspace.py
from sqlalchemy import Column, Integer, String
from base import Base
class WorkspaceModel(Base):
__tablename__ = 'workspaces'
id = Column(Integer, primary_key=True)
name = Column(String)
host.py
from sqlalchemy import Column, Integer, String
from base import Base
class HostModel(Base):
__tablename__ = 'hosts'
id = Column(Integer, primary_key=true)
ip = Column(String)
alembic/env.py
from host import HostModel
from workspace import WorkspaceModel
target_metadata = [HostModel.metadata, WorkspaceModel.metadata]
Error
ValueError: Duplicate table keys across multiple MetaData objects: "hosts", "workspaces"
To make it clear from what @esdotzed and @univerio said, you have to use a single Base.metadata - but still import the individual models.
In the original question, this is how the alembic/env.py should look like:
from base import Base
# This two won't be referenced, but *have* to be imported to populate `Base.metadata`
from host import HostModel
from workspace import WorkspaceModel
target_metadata = Base.metadata
If you didn't import both models, the autogenerated migration would end up deleting your whole database - because Base.metadata doesn't know about any model by itself.