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from __future__ import with_statement
from alembic import context
from alembic.script import ScriptDirectory
from alembic.operations import Operations
from sqlalchemy import engine_from_config, pool, MetaData
from sqlalchemy.ext.declarative import declarative_base
from logging.config import fileConfig
import logging
# 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.
try:
fileConfig(config.config_file_name)
except:
pass
## below block is needed for mssql
meta = MetaData(naming_convention = {
"ix": 'ix_%(column_0_label)s',
"uq": "uq_%(table_name)s_%(column_0_name)s",
"ck": "ck_%(table_name)s_%(column_0_name)s_%(constraint_name)s",
"fk": "fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s",
"pk": "pk_%(table_name)s"
})
Base = declarative_base(metadata=meta)
logger = logging.getLogger('alembic.runtime.setup')
# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata
target_metadata = None
#Comment above line and uncomment below line for mssql
#target_metadata = Base.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.
"""
url = config.get_main_option("sqlalchemy.url")
context.configure(url=url,target_metadata=target_metadata)
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.
"""
engine = engine_from_config(
config.get_section(config.config_ini_section),
prefix='sqlalchemy.',
poolclass=pool.NullPool)
logger.info('Testing for an old alembic_version table.')
connection = engine.connect()
context.configure(
connection=connection,
target_metadata=target_metadata,
version_table='alembic_version'
)
script_location = config.get_main_option('script_location')
found = False
mc = context.get_context()
current_db_revision = mc.get_current_revision()
script = ScriptDirectory.from_config(config)
""" If there was an existing alembic_version table, we need to
check that it's current revision is in the history for the tree
we're working with.
"""
for x in script.iterate_revisions('head', 'base'):
if x.revision == current_db_revision:
""" An alembic_versions table was found and it belongs to
this alembic tree
"""
logger.info(
('An old alembic_version table at revision %s was '
'found for %s. Renaming to alembic_version_%s.'),
current_db_revision, script_location,
script_location)
op = Operations(mc)
try:
with context.begin_transaction():
op.rename_table(
'alembic_version', 'alembic_version_%s'
% script_location)
found = True
except:
logger.error(('Unable to rename alembic_version to '
'alembic_version_%s.'),
script_location)
connection.close()
return
break
if not found:
logger.info('Didn\'t find an old alembic_version table.')
logger.info('Trying alembic_version_%s.' % script_location)
""" We MAY have an alembic_version table that doesn't belong to
this tree but if we still don't have an alembic_version_<tree>
table, alembic will create it.
"""
context.configure(
connection=connection,
target_metadata=target_metadata,
version_table='alembic_version_' + script_location
)
mc = context.get_context()
current_db_revision = mc.get_current_revision()
if current_db_revision:
logger.info(
'Using the alembic_version_%s table at revision %s.',
script_location, current_db_revision)
else:
logger.info('Creating new alembic_version_%s table.',
script_location)
try:
with context.begin_transaction():
context.run_migrations()
finally:
connection.close()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()
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