Defining an Object-Relational Map with Service Builder

In this tutorial, you’ll learn how to define an object relational map so your application can persist data. As an example, you’ll examine the existing Liferay Bookmarks application that uses Service Builder.

The Bookmarks application bookmarks assets in Liferay. The application defines two entities, or model types, to represent an organization’s bookmarks and their folders. These entities are called bookmark entries and bookmark folders. Since a bookmark must have a folder (even if it’s a root folder), the entry entity references a folder entity as one of its attributes.

The Bookmarks application’s source code resides in the bookmarks-api, bookmarks-service, and bookmarks-web modules. Notice the and files in the com.liferay.bookmarks.web.portlet package in the bookmarks-web module. These portlet classes extend Liferay’s MVCPortlet class. They act as the controllers in the MVC pattern. These classes contain the business logic that invokes the Service Builder generated bookmarks services that you’ll learn how to create in this section. The application’s view layer is implemented in the JSPs in the bookmarks-web/src/main/resources/META-INF/resources folder.

This tutorial assumes your application has these types of modules :

  • *-api: Service interfaces
  • *-service: Service implementations
  • *-web: Portlet and controller

The parent folder of these modules is the application folder. The Service Builder project template is available for creating the *-api and *-service modules. Client UI project templates such as the MVCPortlet template are available for creating the *-web module. You can create projects from both templates using either Dev Studio DXP or Blade.

The first step in using Service Builder is to define your model classes and their attributes in a service.xml file. This file typically resides in the *-service module’s root folder, although you can configure your build tool to recognize it in other folders. Service Builder terminology calls model classes entities. For example, the Bookmarks application has two entities: BookmarksEntry and BookmarksFolder. The requirements for each are defined in the bookmarks-service module’s service.xml listed in the <column /> elements.

Once Service Builder reads the service.xml file, you can define your entities. Liferay Dev Studio DXP makes it easy to define entities in your application’s service.xml file. Follow these steps:

  1. Create the service.xml file.

  2. Define global information for the service.

  3. Define service entities.

  4. Define the columns (attributes) for each service entity.

  5. Define relationships between entities.

  6. Define a default order for the entity instances to be retrieved from the database.

  7. Define finder methods that retrieve objects from the database based on specified parameters.

Each step is explained in detail. Start with creating a service.xml file.

« Service Builder PersistenceCreating the service.xml File »
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