Created
October 7, 2015 17:04
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env.py
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from __future__ import with_statement | |
from alembic import context | |
from sqlalchemy import engine_from_config, pool | |
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. | |
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 | |
# 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. | |
exclude_tables = ['third_party_table_included_that_shall_not_be_migrated'] | |
def include_object(object, name, type_, reflected, compare_to): | |
print(name) | |
if type_ == "table" and name in ['third_party_table_included_that_shall_not_be_migrated']: | |
return False | |
else: | |
return True | |
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 = engine.connect() | |
context.configure(connection=connection, | |
target_metadata=target_metadata, | |
include_object=include_object, | |
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() |
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