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Mailu/core/admin/migrations/env.py
kaiyou b8282b1d46 Support named constraints for multiple backends
Supporting multiple backends requires that specific sqlite
collations are not used, thus lowercase is applied to all non
case-sensitive columns. However, lowercasing the database requires
temporary disabling foreign key constraints, which is not possible
on SQLite and requires we specify the constraint names.

This migration specific to sqlite and postgresql drops every
constraint, whether it is named or not, and recreates all of them
with known names so we can later disable them.
2018-12-10 15:16:30 +01:00

92 lines
3.0 KiB
Python
Executable File

from __future__ import with_statement
from alembic import context
from sqlalchemy import engine_from_config, pool
from logging.config import fileConfig
import logging
import tenacity
from tenacity import retry
# 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
from flask import current_app
config.set_main_option('sqlalchemy.url',
current_app.config.get('SQLALCHEMY_DATABASE_URI'))
#target_metadata = current_app.extensions['migrate'].db.metadata
from mailu import models
target_metadata = models.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)
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.readthedocs.org/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.')
engine = engine_from_config(config.get_section(config.config_ini_section),
prefix='sqlalchemy.',
poolclass=pool.NullPool)
connection = retry(engine.connect, stop=tenacity.stop_after_attempt(100), wait=tenacity.wait_random(min=2, max=5))()
context.configure(connection=connection,
target_metadata=target_metadata,
process_revision_directives=process_revision_directives,
**current_app.extensions['migrate'].configure_args)
try:
with context.begin_transaction():
context.run_migrations()
finally:
connection.close()
if context.is_offline_mode():
run_migrations_offline()
else:
run_migrations_online()