Getting Started with the Documents and Media API

Before you start using the Documents and Media API, you must learn these things:

Key Interfaces

The Documents and Media API contains several key interfaces:

  • Documents and Media Services: These interfaces expose all the available Documents and Media functionality:

    Note that Liferay used Service Builder to create these services. Because the remote service contains permission checks, it’s a best practice to call it instead of the local service. See the section below for instructions on getting a service reference.

  • Entity Interfaces: These interfaces represent entities in the Documents and Media library. Here are the primary ones you’ll use:

    • FileEntry: Represents a file.
    • Folder: Represents a folder.
    • FileShortcut: Represents a shortcut to a file.

Getting a Service Reference

Before you can do anything with the Documents and Media API, you must get a service reference. If you’re using OSGi modules, use the @Reference annotation to get a service reference in an OSGi component via Declarative Services. For example, this code gets a reference to DLAppService:

private DLAppService _dlAppService;

If you’re using a standard web module (WAR file), use a Service Tracker to get a reference to the service instead.

Getting the reference this way ensures that you leverage OSGi’s dependency management features. If you must use the Documents and Media services outside of an OSGi component (e.g., in a JSP), then you can use the services’ static *Util classes:

Specifying Repositories

Many methods in the Documents and Media API contain a repositoryId parameter that identifies the Documents and Media repository where the operation is performed. A Site (group) can have multiple repositories, but only one can be accessed via the portal UI. This is called the Site (group) repository, which is effectively a Site’s default repository. To access this repository via the API, provide the group ID as the repositoryId.

You can also get the repositoryId via file (FileEntry), folder (Folder), and file shortcut (FileShortcut) entities. Each of these entities has a getRepositoryId method that gets the ID of its repository. For example, this code gets the repository ID of the FileEntry object fileEntry:

long repositoryId = fileEntry.getRepositoryId();

There may also be cases that require a Repository object. You can get one by creating a RepositoryProvider reference and passing the repository ID to its getRepository method:

private RepositoryProvider repositoryProvider;

Repository repository = repositoryProvider.getRepository(repositoryId);

Even if you only have an entity ID (e.g., a file ID or folder ID), you can still use RepositoryProvider to get a Repository object. To do so, call the RepositoryProvider method for the entity type with the entity ID as its argument. For example, this code gets a folder’s Repository by calling the RepositoryProvider method getFolderRepository with the folder’s ID:

Repository repository = repositoryProvider.getFolderRepository(folderId);

See the RepositoryProvider Javadoc for a list of the methods for other entity types.

Note that there are ways to create repositories programmatically, including repositories private to specific apps. For simplicity, however, the tutorials here access the default site repository.

Specifying Folders

Many API methods require the ID of a folder that they perform operations in or on. For example, such methods may contain parameters like folderId or parentFolderId. Also note that you can use the constant DLFolderConstants.DEFAULT_PARENT_FOLDER_ID to specify the root folder of your current repository.

Service Builder

OSGi Services and Dependency Injection with Declarative Services

Leveraging Dependencies

Service Trackers

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