Following this link: https://alembic.sqlalchemy.org/en/latest/cookbook.html#don-t-generate-any-drop-table-directives-with-autogenerate I wanted flask db migrate to ignore existing tables outside of the context of my application, i thought all i needed to do was add the function from the link and set it in the context.
This is my env.py file, but flask migrate is still erroring because my "testing" table exists in my database, but not in my models:
from __future__ import with_statement
import logging
from logging.config import fileConfig
from flask import current_app
from alembic import context
# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config
# Interpret the config file for Python logging.
# This line sets up loggers basically.
fileConfig(config.config_file_name)
logger = logging.getLogger('alembic.env')
# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
config.set_main_option(
'sqlalchemy.url',
str(current_app.extensions['migrate'].db.get_engine().url).replace(
'%', '%%'))
target_metadata = current_app.extensions['migrate'].db.metadata
# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.
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.
"""
def include_object(object, name, type_, reflected, compare_to):
if type_ == "table" and reflected and compare_to is None:
return False
else:
return True
url = config.get_main_option("sqlalchemy.url")
context.configure(
url=url,
include_object=include_object,
target_metadata=target_metadata,
literal_binds=True
)
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.')
def include_object(object, name, type_, reflected, compare_to):
if type_ == "table" and reflected and compare_to is None:
return False
else:
return True
connectable = current_app.extensions['migrate'].db.get_engine()
with connectable.connect() as connection:
context.configure(
include_object=include_object,
connection=connection,
target_metadata=target_metadata,
process_revision_directives=process_revision_directives,
**current_app.extensions['migrate'].configure_args
)
with context.begin_transaction():
context.run_migrations()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
And this is the script that runs the migration:
flask db init || true
flask db migrate -m "db migration."
flask db upgrade
And this is the error:
raise exc.NoSuchTableError(table.name)
sqlalchemy.exc.NoSuchTableError: testing
