python - SQLAlchemy alembic AmbiguousForeignKeysError for declarative type but not for equivalent non-declarative type -

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i have following alembic migration:

revision = '535f7a49839' down_revision = '46c675c68f4'  alembic import op import sqlalchemy sa sqlalchemy.ext.declarative import declarative_base sqlalchemy.orm import sessionmaker datetime import datetime  session = sessionmaker() base = declarative_base()  metadata = sa.metadata()  # table definition works organisations = sa.table(     'organisations',     metadata,     sa.column('id', sa.integer, primary_key=true),     sa.column('creator_id', sa.integer),     sa.column('creator_staff_member_id', sa.integer), )  """ # doesn't... class organisations(base):     __tablename__ = 'organisations'     id = sa.column(sa.integer, primary_key=true)     creator_id = sa.column(sa.integer)     creator_staff_member_id = sa.column(sa.integer) """   def upgrade():     bind = op.get_bind()     session = session(bind=bind)     session._model_changes = {} # if using flask-sqlalchemy, works around bug     print(session.query(organisations).all())     raise exception("don't succeed")   def downgrade():     pass

now query session.query(organisations).all() works when use imperatively-defined table (the 1 not commented out). if use declarative version, far understand should equivalent, error:

sqlalchemy.exc.ambiguousforeignkeyserror: not determine join condition between parent/child tables on relationship staffmember.organisation - there multiple foreign key paths linking tables. specify 'foreign_keys' argument, providing list of columns should counted containing foreign key reference parent table.

now understand error means: have 2 foreign keys organisations staff_members in actual models. why alembic care these, , how know exist? how migration know called staffmember exists? far understand, alembic should know models explicitly tell in migration.

turns out problem flask-script setup using call alembic. command using call alembic importing code initialise flask app importing actual models.


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