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140 lines
4.1 KiB
Python
140 lines
4.1 KiB
Python
import logging
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from logging.config import fileConfig
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import re
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from sqlalchemy import engine_from_config
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from sqlalchemy import pool
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from alembic import context
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USE_TWOPHASE = False
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# this is the Alembic Config object, which provides
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# access to the values within the .ini file in use.
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config = context.config
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# Interpret the config file for Python logging.
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# This line sets up loggers basically.
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fileConfig(config.config_file_name)
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logger = logging.getLogger("alembic.env")
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# gather section names referring to different
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# databases. These are named "engine1", "engine2"
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# in the sample .ini file.
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db_names = config.get_main_option("databases")
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# add your model's MetaData objects here
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# for 'autogenerate' support. These must be set
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# up to hold just those tables targeting a
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# particular database. table.tometadata() may be
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# helpful here in case a "copy" of
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# a MetaData is needed.
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# from myapp import mymodel
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# target_metadata = {
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# 'engine1':mymodel.metadata1,
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# 'engine2':mymodel.metadata2
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# }
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target_metadata = {}
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# other values from the config, defined by the needs of env.py,
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# can be acquired:
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# my_important_option = config.get_main_option("my_important_option")
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# ... etc.
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def run_migrations_offline():
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"""Run migrations in 'offline' mode.
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This configures the context with just a URL
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and not an Engine, though an Engine is acceptable
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here as well. By skipping the Engine creation
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we don't even need a DBAPI to be available.
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Calls to context.execute() here emit the given string to the
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script output.
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"""
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# for the --sql use case, run migrations for each URL into
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# individual files.
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engines = {}
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for name in re.split(r",\s*", db_names):
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engines[name] = rec = {}
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rec["url"] = context.config.get_section_option(name, "sqlalchemy.url")
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for name, rec in engines.items():
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logger.info("Migrating database %s" % name)
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file_ = "%s.sql" % name
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logger.info("Writing output to %s" % file_)
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with open(file_, "w") as buffer:
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context.configure(
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url=rec["url"],
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output_buffer=buffer,
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target_metadata=target_metadata.get(name),
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literal_binds=True,
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dialect_opts={"paramstyle": "named"},
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)
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with context.begin_transaction():
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context.run_migrations(engine_name=name)
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def run_migrations_online():
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"""Run migrations in 'online' mode.
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In this scenario we need to create an Engine
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and associate a connection with the context.
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"""
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# for the direct-to-DB use case, start a transaction on all
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# engines, then run all migrations, then commit all transactions.
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engines = {}
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for name in re.split(r",\s*", db_names):
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engines[name] = rec = {}
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rec["engine"] = engine_from_config(
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context.config.get_section(name),
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prefix="sqlalchemy.",
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poolclass=pool.NullPool,
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)
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for name, rec in engines.items():
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engine = rec["engine"]
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rec["connection"] = conn = engine.connect()
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if USE_TWOPHASE:
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rec["transaction"] = conn.begin_twophase()
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else:
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rec["transaction"] = conn.begin()
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try:
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for name, rec in engines.items():
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logger.info("Migrating database %s" % name)
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context.configure(
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connection=rec["connection"],
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upgrade_token="%s_upgrades" % name,
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downgrade_token="%s_downgrades" % name,
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target_metadata=target_metadata.get(name),
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)
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context.run_migrations(engine_name=name)
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if USE_TWOPHASE:
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for rec in engines.values():
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rec["transaction"].prepare()
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for rec in engines.values():
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rec["transaction"].commit()
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except:
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for rec in engines.values():
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rec["transaction"].rollback()
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raise
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finally:
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for rec in engines.values():
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rec["connection"].close()
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if context.is_offline_mode():
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run_migrations_offline()
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else:
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run_migrations_online()
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