To have ERXMigrator run at the start of your application, set er.migration.migrateAtStartup = true. This will perform a migration of your EOModels using a series of provided migration classes. By default, models are migrated in the order they appear in the EOModelGroup (that is, effectively random). If you want more control over the order at startup, you can set the er.migration.modelNames property to a comma-separate list of model names. The migrator will migrate them in this order.
For each EOModel, the migrator will lookup [modelName].MigrationClassPrefix and then append version numbers to that name. For instance, if your model named "AuthModel" is being migrated, and you set AuthModel.MigrationClassPrefix=com.mdimension.migration.AuthModel, it will then look for classes named like com.mdimension.migration.AuthModel0, com.mdimension.migration.AuthModel1, etc where the number corresponds to a zero-offset migration version. If MigrationClassPrefix is not set, the migrator will assume the prefix is simply the name of the model. Migration classes are resolved like WOComponents (i.e. packageless by name).
The com.mdimension.migration.AuthModelX classes should implement the IERXMigration interface, and should at least provide an implementation of the upgrade method. If you do not provide a downgrade method, you should throw ERXMigrationFailedException when that method is called to notify the system that the requested migration cannot be performed. As an example, AuthModel1.upgrade(..) will be called to move from version 1 to version 2, and AuthModel1.downgrade(..) will be called to move from version 2 back to version 1. Your lowest version number migration should throw an ERXMigrationFailedException when its downgrade method is called.
Because of complications with database locking, the system will not autocreate tables and per-model rows for you, so if you are using JDBC migration, you should create a table named _DBUpdater with the following (approximately) create statement:
create table _dbupdater ( modelname varchar(100) not null, version integer not null, updatelock integer not null, lockowner varchar(100) )and for each model you want to be able to migrate, you should:
insert into _dbupdater(modelname, version, updatelock, lockowner) values ('YourModelName', -1, 0, NULL) Be aware that not all databases are able to perform DDL operations in a transaction. The result of this is that if a DDL operation fails, your database may be left in an unknown state because the subsequent rollback will fail. Version numbers only increase when each migration completes sucessfully, so in this case, your migration version would be left at the previous version number. Startup migration runs in response to the ApplicationWillFinishLaunchingNotification, so you should not access your EO's until after that notification is complete. ApplicationWillFinishLaunchingNotification is used instead of ApplicationDidFinishLaunchingNotification so that the application will not start accepting requests before migration is complete.
If you are not extending ERXApplication, you can add Migrations into your own application by adding this to your Application constructor:
NSNotificationCenter.defaultCenter().addObserver(this, new NSSelector("willFinishLaunching", ERXConstant.NotificationClassArray), WOApplication.ApplicationWillFinishLaunchingNotification, null); And implementing the willFinishLaunching method like this: public void willFinishLaunching(NSNotification n) { if (ERXMigrator.shouldMigrateAtStartup()) { new ERXMigrator(name() + "-" + number()).migrateToLatest(); } }
@property er.migration.migrateAtStartup if true, migrateToLatest isautomatically called at startup
@property er.migration.[adaptorName].lockClassName the name of theIERXMigrationLock class to use (defaults to er.extensions.migration.ERX[adaptorName]MigrationLock)
@property er.migration.modelNames a comma-separated list of model names to bemigrated in a particular order. If missing, it will default to modelgroup.models() order.
@property er.migration.skipModelNames a comma-separated list of model namesto NOT be migrated.
@property [modelName].MigrationClassPrefix the prefix of the class name touse to upgrade the model named [modelName]. Defaults to [modelName].
@author mschrag
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