Install the package zojax.gae.migration into your project.
Add appropriate settings to your yaml config, for example:
handlers:
- url: /_ah/migration/.*
script: yourapp.app
login: admin
- url: .*
script: yourapp.appRegister your migrations folder of the application next way (typically it is placed in models.py module):
from zojax.gae.migration import register_migrations
register_migrations("your_app_name")By default migrations folder can be named 'migrations', otherwise you need to specify a relative path to your migrations:
register_migrations("your_app_name", "relative/path/to/your/migrations/directory")Also you need to include zojax.gae.migration's routes in your application like this:
from zojax.gae.migration import main_route as migration_route
routes = [
#Your routes list here
...
migration_route,
]For managing migrations visit page http://your.domain/_ah/migration/
Every migration file should be a python module and you need to put into the migrations folder (registered earlier).
The order of the migrations is alphabetical, so the most convenient of file naming is 0001.some_migration.py, 0002.another migration.py etc.
There are two functions in the context of migration: step and transaction. Here is an example of simplest definition of the migration steps logic:
def step1_apply(migration):
try:
# logic for applying the step
except Exception:
migration.fail()
def step1_rollback(migration):
# logic for rolling back the step
migration.succeed() # need to succeed the migration manually
def step2_apply(migration):
# logic for applying the step
migration.succeed() # need to succeed the migration manually
def step2_rollback(migration):
# possible use case
try:
# logic for rolling back the step
except Exception:
migration.fail()The possible usages of the steps are next (without rollback possibility):
step(step1_apply)
step(step2_apply)Or (apply and rollback functionality):
step(step1_apply, step1_rollback)
step(step2_apply, step2_rollback)Or (wrapped in transaction):
transaction(
step(step1_apply, step1_rollback),
step(step2_apply, step2_rollback)
)