5 Groovy Changes

There are four supported inner tags and two callable methods (to override the default confirmation message and checksum value).

General format

This is the general format of a Groovy-based change; all inner tags and methods are optional:

databaseChangeLog = {
   changeSet(author: '...', id: '...') {
      grailsChange {
         init {
             // arbitrary initialization code; note that no
             // database or connection is available
         }
         validate {
            // can call warn(String message) to log a warning
            // or error(String message) to stop processing
         }
         change {
            // arbitrary code; make changes directly and/or return a
            // SqlStatement using the sqlStatement(SqlStatement sqlStatement)
            // method or multiple with sqlStatements(List sqlStatements)
            confirm 'change confirmation message'
         }
         rollback {
            // arbitrary code; make rollback changes directly and/or
            // return a SqlStatement using the sqlStatement(SqlStatement sqlStatement)
            // method or multiple with sqlStatements(List sqlStatements)
            confirm 'rollback confirmation message'
         }
         confirm 'confirmation message'
         checkSum 'override value for checksum'
      }
   }
}

Available variables

These variables are available throughout the change closure:

• changeSet
• the current Liquibase ChangeSet instance
• resourceAccessor
• the current Liquibase ResourceAccessor instance
• ctx
• the Spring ApplicationContext
• application
• the GrailsApplication

The change and rollback closures also have the following available:

• database
• the current Liquibase Database instance
• databaseConnection
• the current Liquibase DatabaseConnection instance, which is a wrapper around the JDBC Connection (but doesn't implement the Connection interface)
• connection
• the real JDBC Connection instance (a shortcut for database.connection.wrappedConnection)
• sql
• a groovy.sql.Sql instance which uses the current connection and can be used for arbitrary queries and updates

init

This is where any optional initialization should happen. You can't access the database from this closure.

validate

If there are any necessary validation checks before executing changes or rollbacks they should be done here. You can log warnings by calling warn(String message) and stop processing by calling error(String message). It may make more sense to use one or more preConditions instead of directly validating here.

change

All migration changes are done in the change closure. You can make changes directly (using the sql instance or the connection) and/or return one or more SqlStatements. You can call sqlStatement(SqlStatement statement) multiple times to register instances to be run. You can also call the sqlStatements(statements) method with an array or list of instances to be run.

rollback

All rollback changes are done in the rollback closure. You can make changes directly (using the sql instance or the connection) and/or return one or more SqlStatements. You can call sqlStatement(SqlStatement statement) multiple times to register instances to be run. You can also call the sqlStatements(statements) method with an array or list of instances to be run.

confirm

The confirm(String message) method is used to specify the confirmation message to be shown. The default is "Executed GrailsChange" and it can be overridden in the change or rollback closures to allow phase-specific messages or outside of both closures to use the same message for the update and rollback phase.

checkSum

The checksum for the change will be generated automatically, but if you want to override the value that gets hashed you can specify it with the checkSum(String value) method.