Finder methods retrieve entity objects from the database based on specified parameters. For each finder defined, Service Builder generates several methods to fetch, find, remove, and count entity instances based on the finder’s parameters.
When supporting Liferay’s multi-tenancy, it’s important to be able to find its entities per Site.
Finders are easy to create:
<finder name="GroupId" return-type="Collection"> <finder-column name="groupId" /> </finder>
The example above is among the simplest of finders, and is one you should always
add if you’re supporting multi-tenancy. This finder returns a collection of
objects that belong to the Site on which your application has been placed.
Service Builder generates finder-related methods (e.g.,
countByGroupId) for the your entities in
*PersistenceImpl classes. The first of these classes is
the interface; the second is its implementation. For example, the Guestbook
application generates its entity finder methods in the
classes found in the
-PersistenceImpl classes in the
You’re not limited to finding by one column, however; you can create multi-column finders:
<finder name="G_S" return-type="Collection"> <finder-column name="groupId" /> <finder-column name="status" /> </finder>
Now you know to configure Service Builder to create finder methods for your entity. Terrific!
Now that you’ve specified the service for your project, you’re ready to build the service by running Service Builder. It’s time to run Service Builder and examine the code it generates.