Creating Data Upgrade Processes for Modules

Some changes you make to a module involve modifying the database. These changes bring with them the need for an upgrade process to move your module’s database from one version to the next. Liferay has an upgrade framework you can use to make this easier to do. It’s a feature-rich framework that makes upgrades safe: the system records the current state of the schema so that if the upgrade fails, the process can revert the module back to its previous version.

Liferay DXP’s upgrade framework executes your module’s upgrades automatically when the new version starts for the first time. You implement concrete data schema changes in upgrade step classes and then register them with the upgrade framework using an upgrade step registrator. In this tutorial, you’ll learn how to do all these things to create an upgrade process for your module.

Here’s what’s involved:

  • Specifying the schema version

  • Declaring dependencies

  • Writing upgrade steps

  • Writing the registrator

  • Waiting for upgrade completion

It’s time to get started.

Specifying the Schema Version

In your module’s bnd.bnd file, specify a Liferay-Require-SchemaVersion header with the new schema version value. Here’s an example schema version header for a module whose new schema is version 1.1.0:

    Liferay-Require-SchemaVersion: 1.1.0

Next, you’ll specify your upgrade’s dependencies.

Declaring Dependencies

In your module’s dependency management file (e.g., Maven POM, Gradle build file, or Ivy ivy.xml file), add a dependency on the com.liferay.portal.upgrade module.

In a build.gradle file, the dependency would look like this:

compile group: "com.liferay", name: "com.liferay.portal.upgrade", version: "2.0.0"

If there are other modules your upgrade process requires, specify them as dependencies.

You’ve configured your module project for the upgrade. It’s time to create upgrade steps to update the database from the current schema version to the new one.

Writing Upgrade Steps

An upgrade step is a class that adapts module data to the module’s target database schema. It can execute SQL commands and DDL files to upgrade the data. As a developer, you can encapsulate upgrade logic in multiple upgrade step classes per schema version.

The upgrade class extends the UpgradeProcess base class, which implements the UpgradeStep interface. Each upgrade step must override the UpgradeProcess class’s method doUpgrade with instructions for modifying the database.

Since UpgradeProcess extends the BaseDBProcess class, you can use its runSQL and runSQLTemplate* methods to execute your SQL commands and SQL DDL, respectively.

If you want to create, modify, or drop tables or indexes by executing DDL sentences from an SQL file, make sure to use ANSI SQL only. Doing this assures the commands work on different databases.

If you need to use non-ANSI SQL, it’s best to write it in the UpgradeProcess class’s runSQL or alter methods, along with tokens that allow porting the sentences to different databases.

For example, consider the journal-service module’s UpgradeSchema upgrade step class:

package com.liferay.journal.internal.upgrade.v0_0_4;

import com.liferay.journal.internal.upgrade.v0_0_4.util.JournalArticleTable;
import com.liferay.journal.internal.upgrade.v0_0_4.util.JournalFeedTable;
import com.liferay.portal.kernel.upgrade.UpgradeMVCCVersion;
import com.liferay.portal.kernel.upgrade.UpgradeProcess;
import com.liferay.portal.kernel.util.StringUtil;

 * @author Eduardo Garcia
public class UpgradeSchema extends UpgradeProcess {

    protected void doUpgrade() throws Exception {
        String template =

        runSQLTemplateString(template, false, false);


            new AlterColumnName(
                "structureId", "DDMStructureKey VARCHAR(75) null"),
            new AlterColumnName(
                "templateId", "DDMTemplateKey VARCHAR(75) null"),
            new AlterColumnType("description", "TEXT null"));

            new AlterColumnName("structureId", "DDMStructureKey TEXT null"),
            new AlterColumnName("templateId", "DDMTemplateKey TEXT null"),
            new AlterColumnName(
                "rendererTemplateId", "DDMRendererTemplateKey TEXT null"),
            new AlterColumnType("targetPortletId", "VARCHAR(200) null"));


The above example class UpgradeSchema uses the runSQLTemplateString method to execute ANSI SQL DDL from an SQL file. To modify column names and column types, it uses the alter method and UpgradeProcess’s UpgradeProcess.AlterColumnName and UpgradeProcess.AlterColumnType inner classes as token classes.

Here’s a simpler example upgrade step from the com.liferay.calendar.service module. It uses the alter method to modify a column type in the calendar booking table:

public class UpgradeCalendarBooking extends UpgradeProcess {

        protected void doUpgrade() throws Exception {
                        new AlterColumnType("description", "TEXT null"));


You can implement upgrade steps just like these for your module schemas.

How you name and organize upgrade steps is up to you. Liferay’s upgrade classes are organized using a package structure similar to this one:

  • some.package.structure
    • upgrade
      • v1_1_0
        • ← Upgrade Step
      • v2_0_0
        • ← Upgrade Step
        • ← Upgrade Step
      • ← Registrator

The example upgrade structure shown above is for a module that has two database schema versions: 1.1.0 and 2.0.0. They’re represented by packages v1_1_0 and v2_0_0. Each version package contains upgrade step classes that update the database. The example upgrade steps focus on fictitious data elements Foo and Bar. The registrator class (MyCustomModuleUpgrade, in this example) is responsible for registering the applicable upgrade steps for each schema version.

Here are some organizational tips:

  • Put all upgrade classes in a sub-package called upgrade.

  • Group together similar database updates (ones that operate on a data element or related data elements) in the same upgrade step class.

  • Create upgrade steps in sub-packages named after each data schema version.

Before continuing with upgrade step registrators, if your application was modularized from a former traditional Liferay plugin application (application WAR) and it uses Service Builder, it requires a Bundle Activator to register itself in Liferay DXP’s Release_ table. If this is the case for your application, create and register a Bundle Activator and then return here to write your upgrade step registrator.

Writing the Upgrade Step Registrator

A module’s upgrade step registrator notifies Liferay’s upgrade framework of all the upgrade steps to update the module data for each schema version. It specifies the module’s entire upgrade process. The upgrade framework executes the upgrade steps to update the current module data to the latest schema.

For example, the upgrade step registrator class MyCustomModuleUpgrade (below) registers upgrade steps incrementally for each schema version (past and present):

package com.liferay.mycustommodule.upgrade;

import com.liferay.portal.upgrade.registry.UpgradeStepRegistrator;

import org.osgi.service.component.annotations.Component;

@Component(immediate = true, service = UpgradeStepRegistrator.class)
public class MyCustomModuleUpgrade implements UpgradeStepRegistrator {

    public void register(Registry registry) {
            "com.liferay.mycustommodule", "0.0.0", "2.0.0",
            new DummyUpgradeStep());

            "com.liferay.mycustommodule", "1.0.0", "1.1.0",
            new com.liferay.mycustommodule.upgrade.v1_1_0.UpgradeFoo());

            "com.liferay.mycustommodule", "1.1.0", "2.0.0",
            new com.liferay.mycustommodule.upgrade.v2_0_0.UpgradeFoo(),
            new com.liferay.mycustommodule.upgrade.v2_0_0.UpgradeBar());


The registrator’s register method informs the upgrade framework about each new schema and associated upgrade steps to adapt data to it. Each schema upgrade is represented by a registration. A registration is an abstraction for all the changes you need to apply to the database from one schema version to the next one.

The following diagram illustrates the relationship between the registrator and the upgrade steps.

Figure 1: In a registrator class, the developer specifies a registration for each schema version upgrade. The upgrade steps handle the database updates.

Figure 1: In a registrator class, the developer specifies a registration for each schema version upgrade. The upgrade steps handle the database updates.

The previous example MyCustomModuleUpgrade registrator class listing shows how this works.

The registrator class declares itself to be an OSGi Component of service type UpgradeStepRegistrator.class. The @Component annotation registers the class to the OSGi framework as the module’s upgrade step registrator. The attribute immediate = true tells the OSGi framework to activate this module immediately after it’s installed.

The registrator implements the UpgradeStepRegistrator interface, which is in the com.liferay.portal.upgrade module. The interface declares a register method that the registrator must override. In that method, the registrator implements all the module’s upgrade registrations.

Upgrade registrations are defined by the following values:

  • Module’s bundle symbolic name
  • Schema version to upgrade from (as a String)
  • Schema version to upgrade to (as a String)
  • List of upgrade steps

The example registrator MyCustomModuleUpgrade registers three upgrades:

  • 0.0.0 to 2.0.0
  • 1.0.0 to 1.1.0
  • 1.1.0 to 2.0.0

The MyCustomModuleUpgrade registrator’s first registration is applied by the upgrade framework if the module has not been installed previously. Its list of upgrade steps contains only one: new DummyUpgradeStep().

	"com.liferay.document.library.web", "0.0.0", "2.0.0",
	new DummyUpgradeStep());

The DummyUpgradeStep class provides an empty upgrade step. The MyCustomModuleUpgrade registrator defines this registration so that the upgrade framework records the module’s latest schema version (i.e., 2.0.0) in Liferay DXP’s Release_ table.

Important: Modules that use Service Builder should not define a registration for their initial database schema version, as Service Builder already records their schema versions to Liferay DXP’s Release_ table. Modules that don’t use Service Builder, however, should define a registration for their initial schema.

The MyCustomUpgrade registrator’s next registration (from schema version 1.0.0 to 1.1.0) includes one upgrade step.

	"com.liferay.mycustommodule", "1.0.0", "1.1.0",
          new com.liferay.mycustommodule.upgrade.v1_1_0.UpgradeFoo());

The upgrade step’s fully qualified class name is required because classes named UpgradeFoo are in package com.liferay.mycustommodule.upgrade.v1_1_0and com.liferay.mycustommodule.upgrade.v2_0_0.

The registrator’s final registration (from schema version 1.1.0 to 2.0.0) contains two upgrade steps.

    "com.liferay.mycustommodule", "1.1.0", "2.0.0",
    new com.liferay.mycustommodule.upgrade.v2_0_0.UpgradeFoo(),
    new UpgradeBar());

Both upgrade steps, UpgradeFoo and UpgradeBar, reside in the module’s com.liferay.mycustommodule.upgrade.v2_0_0 package. The fully qualified class name com.liferay.mycustommodule.upgrade.v2_0_0.UpgradeFoo is used for the UpgradeFoo class, while the simple class name UpgradeBar is fine for the second upgrade step.

A registration’s upgrade step list can consist of as many upgrade steps as needed.

Important: If your upgrade step uses an OSGi service, your upgrade must wait for that service’s availability. To specify that your upgrade is to be executed only after that service is available, add an OSGi reference to that service.

For example, the WikiServiceUpgrade registrator class references the SettingsFactory class. The upgrade step class UpgradePortletSettings upgrade step uses it. Here’s the WikiServiceUpgrade class:

@Component(immediate = true, service = UpgradeStepRegistrator.class)
public class WikiServiceUpgrade implements UpgradeStepRegistrator {

	public void register(Registry registry) {
			"", "0.0.1", "0.0.2", new UpgradeSchema());

			"", "0.0.2", "0.0.3",
			new UpgradeKernelPackage(), new UpgradePortletId());

			"", "0.0.3", "1.0.0",
			new UpgradeCompanyId(), new UpgradeLastPublishDate(),
			new UpgradePortletPreferences(),
			new UpgradePortletSettings(_settingsFactory),
			new UpgradeWikiPageResource());

	@Reference(unbind = "-")
	protected void setSettingsFactory(SettingsFactory settingsFactory) {
		_settingsFactory = settingsFactory;

	private SettingsFactory _settingsFactory;


In the third registration in the listing above, the UpgradePortletSettings upgrade step uses the SettingsFactory service. The setSettingsFactory method’s @Reference annotation declares that the registrator class depends on and must wait for the SettingsFactory service to be available in the run time environment. The annotation’s attribute setting unbind = "-" indicates that the registrator class has no method for unbinding the service.

Next, you must make sure the module’s upgrade is executed before making its services available.

Waiting for Upgrade Completion

Before module services that access the database are used, the database should be upgraded to the latest database schema.

As a convenience, configuring the Bnd header Liferay-Require-SchemaVersion to the latest schema version is all that’s required to assure the database is upgraded for Service Builder services.

For all other services, the developer can assure database upgrade by specifying an @Reference annotation that targets the containing module and its latest schema version.

Here are the target’s required attributes:

  • module’s bundle symbolic name
  • release.schema.version: module’s current schema version

For example, the module’s PageCommentsPortlet class assures upgrading to schema version 1.0.0 by defining the following reference:

    target = "(&(",
    unbind = "-"
protected void setRelease(Release release) {

Dependencies between OSGi services can reduce the number of service classes in which upgrade reference annotations are needed. For example, there’s no need to add an upgrade reference in a dependent service, if the dependency already refers to the upgrade.

Now you know how to create data upgrades for all your modules. You specify the new data schema version in the bnd.bnd file, add a reference to your module and to the schema version to assure upgrade execution if the module doesn’t use Service Builder, and add a dependency on the com.liferay.portal.upgrade module. For the second part of the process, you create upgrade step classes to update the database schema and register the upgrade steps in a registrator class. That’s all there is to it!

Upgrade Processes for Former Service Builder Plugins

Upgrading Plugins to Liferay 7


Migrating Data Upgrade Processes to the New Framework for Modules

« Introduction to Data UpgradesUpgrade Processes for Former Service Builder Plugins »
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