Hi all, I'm working on a way to perform migrations entirely within my python application using the alembic API. I do not envision any complex DB changes for this project (at most adding a new table) so I figure autogenerate should be completely sufficient. At the moment, I can successfully detect schema changes between the application and the DB as it is written on disk (sqlite3), however I cannot seem to perform the actual upgrade to the DB.
This is what I have thus far, with the 'fn=self.do_upgrade()' bit coming from this StackOverflow post <https://stackoverflow.com/questions/39021059/how-to-run-a-migration-with-python-alembic-by-code> as without that I was hitting the same exception as the poster there: self.alembic_cfg = Config() self.alembic_cfg.set_main_option("script_location", "migrations") self.alembic_cfg.set_main_option("url", "sqlite://mydb.db") self.alembic_script = ScriptDirectory.from_config(self.alembic_cfg) self.alembic_env = EnvironmentContext(self.alembic_cfg, self. alembic_script) self.migrate() def migrate(self): conn = engine.connect() metadata = Base.metadata self.alembic_env.configure(connection=conn, target_metadata=metadata , fn=self.do_upgrade) self.alembic_context = self.alembic_env.get_context() autogenerate.compare_metadata(self.alembic_context, metadata) autogenerate.produce_migrations(self.alembic_context, metadata) with self.alembic_env.begin_transaction(): self.alembic_env.run_migrations() def do_upgrade(self, revision, context): return self.alembic_script._upgrade_revs(self.alembic_script. get_heads(), revision) Assume I have this table to start: Base = declarative_base() class Events(Base): __tablename__ = 'events' id = Column(Integer, primary_key=True) name = Column(String(100), nullable=False) [...] engine = create_engine("sqlite:///mydb.db") Base.metadata.create_all(engine) Base.metadata.bind = engine And I want to add an arbitrary column: test = Column(String(10), default='test') As said earlier, the above will detect the change, as seen by autogenerate. compare_metadata(self.alembic_context, metadata): [('add_column', None, 'events', Column('test', String(length=10), table=< events>, default=ColumnDefault('test')))] However, even though run_migrations() appears to run without issue (no exceptions or similar), the written DB is not updated, and I cannot access the 'test' column for any entry in the 'events' table with this exception: sqlite3.OperationalError: no such column: events.test I have noticed that within do_upgrade(), that both get_heads() and revision are empty. I assume this is because I have not done a previous migration on this existing DB, but I'm not sure how to proceed there. I have only run `alembic --init` in the project directory (with mydb.db being in the top-level directory). I have a feeling I'm missing something that is probably incredibly obvious, so any help here would be very much appreciated. -- You received this message because you are subscribed to the Google Groups "sqlalchemy-alembic" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy-alembic+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
