Implementing Methods to Get and Count Entities

Service Builder generates findBy* methods and countBy* methods in your *Persistence classes based on your service.xml file’s finders. You can leverage finder methods in your local services to get and count entities.

  • Getters: get* methods return entity instances matching criteria.
  • Counters: get*Count methods return the number of instances matching criteria

Start with getting entities that match criteria.

Getter Methods

The findByPrimaryKey methods and findBy* methods search for and return entity instances based on criteria. Your local service implementation must only wrap calls to the finder methods that get what you want.

Here’s how to create a method that gets an entity based on an ID (primary key):

  1. Create a method using this format:

    public [ENTITY] get[ENTITY_NAME](long id) {
        return [ENTITY]Persistence.findByPrimaryKey(id);
  2. Replace [ENTITY] and [ENTITY_NAME] with the respective entity type and entity name (or nickname).

  3. Run Service Builder to propagate the method to your local service interface.

Here’s how to get entities based on criteria:

  1. Identify the criteria for finding the entity instance(s).

  2. If there is no finder element for the criteria, create one for it and run Service Builder.

  3. Determine the *Persistence class findBy* method you want to call. Depending on your finder element columns, Service Builder might overload the method to include these parameters:

    • int start and int end parameters for specifying a range of entities.
    • com.liferay.portal.kernel.util.OrderByComparator orderByComparator parameter for arranging the matching entities.
  4. Specify your get* method signature, making sure to account for the *Persistence class findBy* method parameters you must satisfy. Use this method format:

    public List<[ENTITY]> get[DESCRIBE_THE_ENTITIES](...) {

    Replace [ENTITY] with the entity type. Replace [DESCRIBE_THE_ENTITIES] with a descriptive name for the entities you’re getting.

  5. Call the *Persistence class findBy* method and return the list of matching entities.

  6. Run Service Builder.

For example, method getGroupEntries from BookmarksEntryLocalServiceImpl returns a range of BookmarksEntrys associated with a Group primary key:

public List<BookmarksEntry> getGroupEntries(
    long groupId, int start, int end) {

    return bookmarksEntryPersistence.findByG_S(
        groupId, WorkflowConstants.STATUS_APPROVED, start, end,
        new EntryModifiedDateComparator());

Of the BookmarksEntrys associated with workflows, this method only matches approved ones (WorkflowConstants.STATUS_APPROVED). It uses a new EntryModifiedDateComparator to order the matching BookmarksEntrys by modification date.

Now you know how to leverage finder methods to get entities. Methods that count entities are next.

Counter Methods

Counting entities is just as easy as getting them. Your *Persistence class countBy* methods do all the work. Service Builder generates countBy* methods based on each finder and its columns.

  1. Identify the criteria for entity instances you’re counting and determine the *Persistence class countBy* method that satisfies the criteria.

  2. Create a get*Count method signature following this format:

    public int get[DESCRIBE_THE_ENTITIES]Count(...) {

    Replace [DESCRIBE_THE_ENTITIES] with a descriptive name for the entities you’re counting.

  3. Call the *Persistence class’ countBy method and return the value. For example, the method getEntriesCount from BookmarksEntryLocalServiceImpl returns the number of BookmarksEntrys that have a workflow status of status and that are associated with a group (matching groupId) and a folder (matching folderId).

    public int getEntriesCount(long groupId, long folderId, int status) {
    	return bookmarksEntryPersistence.countByG_F_S(
    		groupId, folderId, status);

Now your local service can get entities matching your criteria and return quick entity counts.

Creating Local Services

Implementing an add method

Defining Service Entity Finder Methods

Understanding the Code Generated by Service Builder

« Implementing update and delete MethodsImplementing Any Other Business Logic »
Was this article helpful?
0 out of 0 found this helpful