I'm currently working on a python backend using Flask, SQLAlchemy and flask-migrate/alembic. When I run
flask db upgrade head (after performing init and migrate), I get the following error for the 'spatial_ref_sys' table of PostGIS:
qlalchemy.exc.InternalError: (psycopg2.errors.DependentObjectsStillExist) cannot drop table spatial_ref_sys because extension postgis requires it HINT: You can drop extension postgis instead.
To exclude the spatial_ref_sys table, I modified the env.py file as follows:
def include_object(object, name, type_, reflected, compare_to):
if type_ == "table" and name == 'spatial_ref_sys':
return False
else:
return True
def run_migrations_offline():
"""Run migrations in 'offline' mode.
This configures the context with just a URL
and not an Engine, though an Engine is acceptable
here as well. By skipping the Engine creation
we don't even need a DBAPI to be available.
Calls to context.execute() here emit the given string to the
script output.
"""
url = config.get_main_option("sqlalchemy.url")
context.configure(
url=url, target_metadata=get_metadata(), literal_binds=True, include_object=include_object
)
with context.begin_transaction():
context.run_migrations()
def run_migrations_online():
"""Run migrations in 'online' mode.
In this scenario we need to create an Engine
and associate a connection with the context.
"""
# this callback is used to prevent an auto-migration from being generated
# when there are no changes to the schema
# reference: http://alembic.zzzcomputing.com/en/latest/cookbook.html
def process_revision_directives(context, revision, directives):
if getattr(config.cmd_opts, 'autogenerate', False):
script = directives[0]
if script.upgrade_ops.is_empty():
directives[:] = []
logger.info('No changes in schema detected.')
connectable = get_engine()
with connectable.connect() as connection:
context.configure(
connection=connection,
target_metadata=get_metadata(),
process_revision_directives=process_revision_directives,
**current_app.extensions['migrate'].configure_args,
include_object=include_object
)
with context.begin_transaction():
context.run_migrations()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
Unfortunately the modifications do not have any effect. Indeed, it seems as the added 'include_object' function is not executed at all. I compared it to the documentation (https://alembic.sqlalchemy.org/en/latest/autogenerate.html) but could not identify any mistake. Do I miss anything?
