|
| 1 | +from __future__ import with_statement |
| 2 | + |
| 3 | +import logging |
| 4 | +from logging.config import fileConfig |
| 5 | + |
| 6 | +from sqlalchemy import engine_from_config |
| 7 | +from sqlalchemy import pool |
| 8 | + |
| 9 | +from alembic import context |
| 10 | + |
| 11 | +# this is the Alembic Config object, which provides |
| 12 | +# access to the values within the .ini file in use. |
| 13 | +config = context.config |
| 14 | + |
| 15 | +# Interpret the config file for Python logging. |
| 16 | +# This line sets up loggers basically. |
| 17 | +fileConfig(config.config_file_name) |
| 18 | +logger = logging.getLogger('alembic.env') |
| 19 | + |
| 20 | +# add your model's MetaData object here |
| 21 | +# for 'autogenerate' support |
| 22 | +# from myapp import mymodel |
| 23 | +# target_metadata = mymodel.Base.metadata |
| 24 | +from flask import current_app |
| 25 | +config.set_main_option( |
| 26 | + 'sqlalchemy.url', current_app.config.get( |
| 27 | + 'SQLALCHEMY_DATABASE_URI').replace('%', '%%')) |
| 28 | +target_metadata = current_app.extensions['migrate'].db.metadata |
| 29 | + |
| 30 | +# other values from the config, defined by the needs of env.py, |
| 31 | +# can be acquired: |
| 32 | +# my_important_option = config.get_main_option("my_important_option") |
| 33 | +# ... etc. |
| 34 | + |
| 35 | + |
| 36 | +def run_migrations_offline(): |
| 37 | + """Run migrations in 'offline' mode. |
| 38 | +
|
| 39 | + This configures the context with just a URL |
| 40 | + and not an Engine, though an Engine is acceptable |
| 41 | + here as well. By skipping the Engine creation |
| 42 | + we don't even need a DBAPI to be available. |
| 43 | +
|
| 44 | + Calls to context.execute() here emit the given string to the |
| 45 | + script output. |
| 46 | +
|
| 47 | + """ |
| 48 | + url = config.get_main_option("sqlalchemy.url") |
| 49 | + context.configure( |
| 50 | + url=url, target_metadata=target_metadata, literal_binds=True |
| 51 | + ) |
| 52 | + |
| 53 | + with context.begin_transaction(): |
| 54 | + context.run_migrations() |
| 55 | + |
| 56 | + |
| 57 | +def run_migrations_online(): |
| 58 | + """Run migrations in 'online' mode. |
| 59 | +
|
| 60 | + In this scenario we need to create an Engine |
| 61 | + and associate a connection with the context. |
| 62 | +
|
| 63 | + """ |
| 64 | + |
| 65 | + # this callback is used to prevent an auto-migration from being generated |
| 66 | + # when there are no changes to the schema |
| 67 | + # reference: http://alembic.zzzcomputing.com/en/latest/cookbook.html |
| 68 | + def process_revision_directives(context, revision, directives): |
| 69 | + if getattr(config.cmd_opts, 'autogenerate', False): |
| 70 | + script = directives[0] |
| 71 | + if script.upgrade_ops.is_empty(): |
| 72 | + directives[:] = [] |
| 73 | + logger.info('No changes in schema detected.') |
| 74 | + |
| 75 | + connectable = engine_from_config( |
| 76 | + config.get_section(config.config_ini_section), |
| 77 | + prefix='sqlalchemy.', |
| 78 | + poolclass=pool.NullPool, |
| 79 | + ) |
| 80 | + |
| 81 | + with connectable.connect() as connection: |
| 82 | + context.configure( |
| 83 | + connection=connection, |
| 84 | + target_metadata=target_metadata, |
| 85 | + process_revision_directives=process_revision_directives, |
| 86 | + **current_app.extensions['migrate'].configure_args |
| 87 | + ) |
| 88 | + |
| 89 | + with context.begin_transaction(): |
| 90 | + context.run_migrations() |
| 91 | + |
| 92 | + |
| 93 | +if context.is_offline_mode(): |
| 94 | + run_migrations_offline() |
| 95 | +else: |
| 96 | + run_migrations_online() |
0 commit comments