Defining the Columns (Attributes) for Each Service Entity

An entity’s columns represent its attributes. These attributes map table fields to Java object fields. To add attributes for your entity, drill down to its columns in the Overview mode outline of the service.xml file. From the outline, expand the Entities node and expand an entity node. Then select the Columns node. Liferay Dev Studio DXP displays a table of the entity’s columns.

Figure 1: Liferay Dev Studio DXP facilitates defining table columns for entities.

Service Builder creates a database field for each column you add to the service.xml file. It maps a database field type appropriate to the Java type specified for each column, and it does this across all the databases Liferay supports. Once Service Builder runs, it generates a Hibernate configuration that handles the object-relational mapping. Service Builder automatically generates getter/setter methods in the model class for these attributes. The column’s Name specifies the name used in the getters and setters that are created for the entity’s Java field. The column’s Type indicates the Java type of this field for the entity. If a column’s Primary (i.e., primary key) attribute value is set to true, then the column becomes part of the primary key for the entity. An entity’s primary key uniquely identifies the entity. If only one column has Primary set to true, then that column represents the entire primary key for the entity. This is the case in the Bookmarks application. However, it’s possible to use multiple columns as the primary key for an entity. In this case, the combination of columns makes up a compound primary key for the entity.

Note: The Implementing an Add Method article demonstrates how to generate unique primary keys for entity instances.

Create Entity Columns

Similar to the way you used the form table for adding entities, add attribute columns for each of your entities.

1. Create each attribute by clicking on the Add icon ().

2. Fill in the attribute’s name

3. Select the attribute’s type. While your cursor is in a column’s Type field, an option icon appears. Click this icon to select the appropriate type for the column.

4. Specify whether the attribute is a primary key for the entity.

Note: On deploying a *service module, Service Builder automatically generates indexes for all entity primary keys.

Create a column for each attribute of your entity or entities.

Support Multi-tenancy

In addition to columns for your entity’s primary key and attributes, add portal instance ID and site ID columns. They let your portlet support Liferay’s multi-tenancy features, so that each portal instance and each site in a portal instance can have independent sets of portlet data. To hold the site’s ID, add a column called groupId of type long. To hold the portal instance’s ID, add a column called companyId of type long. To add these columns to your entities, follow the table below.

Portal and site scope columns

Name	Type	Primary
companyId	long	no
groupId	long	no

Track Ownership

To track each entity instance’s owner, add a column called userId of type long.

User column

Name	Type	Primary
userId	long	no

Audit Entities

Lastly, you can add columns to help audit your entities. For example, you could create a column named createDate of type Date to note an entity instance’s creation date. And add a column named modifiedDate of type Date to track the last time an entity instance was modified.

Audit columns

Name	Type	Primary
userId	long	no
createDate	Date	no
modifiedDate	Date	no

Great! Your entities have columns that not only represent their attributes, but also support multi-tenancy and entity auditing. Next, you’ll learn how to specify the relationship service entities.