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Diffstat (limited to 'mediagoblin/db/migrations')
-rw-r--r-- | mediagoblin/db/migrations/README | 57 | ||||
-rw-r--r-- | mediagoblin/db/migrations/env.py | 71 | ||||
-rw-r--r-- | mediagoblin/db/migrations/script.py.mako | 22 | ||||
-rw-r--r-- | mediagoblin/db/migrations/versions/.gitkeep | 0 |
4 files changed, 150 insertions, 0 deletions
diff --git a/mediagoblin/db/migrations/README b/mediagoblin/db/migrations/README new file mode 100644 index 00000000..93d85eff --- /dev/null +++ b/mediagoblin/db/migrations/README @@ -0,0 +1,57 @@ +Migration Guide +--------------- + +Alembic comes with a CLI called ``alembic``. + +Create a Migration +^^^^^^^^^^^^^^^^^^ + +Lets create our first migration:: + + $ alembic revision -m "add favourite_band field" + Generating + /your/gmg/path/mediagoblin/db/migrations/versions/1e3793de36a_add_favourite_band_field.py ... done + +By default, migration files have two methods: ``upgrade`` and ``downgrade``. +Alembic will invoke these methods to apply the migrations to your current +database. + +Now, we need to edit our newly created migration file +``1e3793de36a_add_favourite_band_field.py`` to add a new column ``favourite_band`` +to ``core__users`` table:: + + def upgrade(): + op.add_column('core__users', sa.Column('favourite_band', sa.Unicode(100))) + + + def downgrade(): + op.drop_column('core__users', 'favourite_band') + +.. note:: + + Alembic can also generate `automatic migrations <http://alembic.readthedocs.org/en/latest/tutorial.html#auto-generating-migrations>`__. + +Then we can run ``gmg dbupdate`` to apply the new migration:: + + $ gmg dbupdate + INFO [alembic.migration] Context impl SQLiteImpl. + INFO [alembic.migration] Will assume non-transactional DDL. + INFO [alembic.migration] Running upgrade None -> 1e3793de36a, add favourite band field + +If you want to revert that migration, simply run:: + + $ alembic downgrade -1 + +.. warning:: + + Currently, Alembic cannot do ``DROP COLUMN``, ``ALTER COLUMN`` etc. + operations in SQLite. Please see https://bitbucket.org/zzzeek/alembic/issue/21/column-renames-not-supported-on-sqlite + for detailed information. + +Glossary +^^^^^^^^ + +* ``alembic.ini``: The Alembic configuration file. The ``alembic`` CLI will + look that file everytime it invaked. +* ``mediagoblin/db/migrations/versions/``: Alembic will add new migration files + to this directory. diff --git a/mediagoblin/db/migrations/env.py b/mediagoblin/db/migrations/env.py new file mode 100644 index 00000000..712b6164 --- /dev/null +++ b/mediagoblin/db/migrations/env.py @@ -0,0 +1,71 @@ +from __future__ import with_statement +from alembic import context +from sqlalchemy import engine_from_config, pool +from logging.config import fileConfig + +# 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) + +# add your model's MetaData object here +# for 'autogenerate' support +# from myapp import mymodel +# target_metadata = mymodel.Base.metadata +target_metadata = None + +# 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) + + connection = engine.connect() + context.configure( + connection=connection, + target_metadata=target_metadata + ) + + try: + with context.begin_transaction(): + context.run_migrations() + finally: + connection.close() + +if context.is_offline_mode(): + run_migrations_offline() +else: + run_migrations_online() + diff --git a/mediagoblin/db/migrations/script.py.mako b/mediagoblin/db/migrations/script.py.mako new file mode 100644 index 00000000..95702017 --- /dev/null +++ b/mediagoblin/db/migrations/script.py.mako @@ -0,0 +1,22 @@ +"""${message} + +Revision ID: ${up_revision} +Revises: ${down_revision} +Create Date: ${create_date} + +""" + +# revision identifiers, used by Alembic. +revision = ${repr(up_revision)} +down_revision = ${repr(down_revision)} + +from alembic import op +import sqlalchemy as sa +${imports if imports else ""} + +def upgrade(): + ${upgrades if upgrades else "pass"} + + +def downgrade(): + ${downgrades if downgrades else "pass"} diff --git a/mediagoblin/db/migrations/versions/.gitkeep b/mediagoblin/db/migrations/versions/.gitkeep new file mode 100644 index 00000000..e69de29b --- /dev/null +++ b/mediagoblin/db/migrations/versions/.gitkeep |