File Content: env.py from __future__ import with_statement from alembic import context from sqlalchemy import engine_from_config, pool from logging.config import fileConfig import logging import re USE_TWOPHASE = False # 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') # gather section names referring to different # databases. These are named "engine1", "engine2" # in the sample .ini file. db_names = config.get_main_option('databases') # add your model's MetaData objects here # for 'autogenerate' support. These must be set # up to hold just those tables targeting a # particular database. table.tometadata() may be # helpful here in case a "copy" of # a MetaData is needed. # from myapp import mymodel # target_metadata = { # 'engine1':mymodel.metadata1, # 'engine2':mymodel.metadata2 #} target_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. """ # for the --sql use case, run migrations for each URL into # individual files. engines = {} for name in re.split(r',\s*', db_names): engines[name] = rec = {} rec['url'] = context.config.get_section_option(name, "sqlalchemy.url") for name, rec in engines.items(): logger.info("Migrating database %s" % name) file_ = "%s.sql" % name logger.info("Writing output to %s" % file_) with open(file_, 'w') as buffer: context.configure(url=rec['url'], output_buffer=buffer, target_metadata=target_metadata.get(name), literal_binds=True) with context.begin_transaction(): context.run_migrations(engine_name=name) 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. """ # for the direct-to-DB use case, start a transaction on all # engines, then run all migrations, then commit all transactions. engines = {} for name in re.split(r',\s*', db_names): engines[name] = rec = {} rec['engine'] = engine_from_config( context.config.get_section(name), prefix='sqlalchemy.', poolclass=pool.NullPool) for name, rec in engines.items(): engine = rec['engine'] rec['connection'] = conn = engine.connect() if USE_TWOPHASE: rec['transaction'] = conn.begin_twophase() else: rec['transaction'] = conn.begin() try: for name, rec in engines.items(): logger.info("Migrating database %s" % name) context.configure( connection=rec['connection'], upgrade_token="%s_upgrades" % name, downgrade_token="%s_downgrades" % name, target_metadata=target_metadata.get(name) ) context.run_migrations(engine_name=name) if USE_TWOPHASE: for rec in engines.values(): rec['transaction'].prepare() for rec in engines.values(): rec['transaction'].commit() except: for rec in engines.values(): rec['transaction'].rollback() raise finally: for rec in engines.values(): rec['connection'].close() if context.is_offline_mode(): run_migrations_offline() else: run_migrations_online() Submit