A powerful API underlies the Documents and Media library. You can leverage this API in your own apps. For example, you could create an app that lets users upload files to the Documents and Media library. Your app could even let users update, delete, and copy files.
Here, you’ll learn how to use the Documents and Media library’s API. Note that this is a large API and it may seem daunting at first. To keep backwards compatibility, the API has different entry points and multiple methods or classes with similar functionality. Fortunately, you don’t need to learn all of them. The content here focuses on the API’s most useful classes and methods.
Also note that the Documents and Media app is itself a consumer of this API—Liferay’s developers used the API to implement the app’s functionality. Therefore, code from this app is used as an example of how to use the API.
Before you start using the Documents and Media API, you must learn these things:
Key Interfaces: The interfaces you’ll use most while using the API.
Getting a Service Reference: A service reference is required for calling the API’s services.
Specifying Repositories: How to specify which Documents and Media repository to work with.
Specifying Folders: How to specify which Documents and Media folder to work with.
The Documents and Media API contains several key interfaces:
Documents and Media Services: These interfaces expose all the available Documents and Media functionality:
DLAppLocalService: The local service.
DLAppService: The remote service. This service wraps the local service methods in permission checks.
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
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.
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
get a service reference in an OSGi component via Declarative Services.
For example, this code gets a reference to
@Reference 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
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
Many methods in the Documents and Media API contain a
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 repository, which is
effectively a Site’s default repository. To access this repository via the API,
provide the group ID as the
You can also get the
repositoryId via file (
FileEntry), folder (
and file shortcut (
FileShortcut) entities. Each of these entities has a
getRepositoryId method that gets its repository’s ID. For example, this code
gets the repository ID of the
long repositoryId = fileEntry.getRepositoryId();
There may also be cases that require a
Repository object. You can get one by
RepositoryProvider reference and passing the repository ID to its
@Reference private RepositoryProvider repositoryProvider; Repository repository = repositoryProvider.getRepository(repositoryId);
Even if you only have an entity ID (e.g., a file or folder ID), you can still
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
getFolderRepository with the folder’s ID:
Repository repository = repositoryProvider.getFolderRepository(folderId);
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 examples here access the default site repository.
Many API methods require the ID of a folder that they perform operations in or
on. For example, such methods may contain parameters like
parentFolderId. Also note that you can use the constant
DLFolderConstants.DEFAULT_PARENT_FOLDER_ID to specify the root folder of your