MVC Action Command

Liferay’s MVC framework lets you split your portlet’s action methods into separate classes. This can be very helpful in portlets that have many actions. Each action URL in your portlet’s JSPs then calls the appropriate action class when necessary.

First, use the <portlet:actionURL> tag to create the action URL in your JSP. For example, the edit blog entry action in Liferay’s Blogs app is defined in the edit_entry.jsp file as follows:

<portlet:actionURL name="/blogs/edit_entry" var="editEntryURL" />

When the action URL is triggered, the matching action class processes the action. Implement the action by creating a class that implements the MVCActionCommand interface. To avoid writing oodles of boilerplate code, your *MVCActionCommand class should extend the BaseMVCActionCommand class instead of implementing MVCActionCommand directly. The BaseMVCActionCommand class already implements MVCActionCommand and provides many useful method implementations. Naming your *MVCActionCommand class after the action it performs is a good convention. For example, if your action edits some kind of entry, you could name its class EditEntryMVCActionCommand.

Your *MVCActionCommand class must also have a @Component annotation like the following. Set the property javax.portlet.name to your portlet’s internal ID, and the property mvc.command.name to the value of the name property in your JSP’s matching actionURL. To register the component in the OSGi container as using the MVCActionCommand class, you must set the service property to MVCActionCommand.class:

@Component(
    immediate = true,
    property = {
        "javax.portlet.name=your_portlet_name_YourPortlet",
        "mvc.command.name=/your/jsp/action/url"
    },
    service = MVCActionCommand.class
)
public class YourMVCActionCommand extends BaseMVCActionCommand {
    // implement your action
}

For example, this is the @Component annotation for the Blogs app’s EditEntryMVCActionCommand class:

@Component(
    immediate = true,
    property = {
        "javax.portlet.name=" + BlogsPortletKeys.BLOGS,
        "javax.portlet.name=" + BlogsPortletKeys.BLOGS_ADMIN,
        "javax.portlet.name=" + BlogsPortletKeys.BLOGS_AGGREGATOR,
        "mvc.command.name=/blogs/edit_entry"
    },
    service = MVCActionCommand.class
)
public class EditEntryMVCActionCommand extends BaseMVCActionCommand {
    // the app's edit blog entry action implementation
}

Note that you can use multiple javax.portlet.name values to indicate the component works with multiple portlets.

In your *MVCActionCommand class, process the action by overriding the BaseMVCActionCommand class’s doProcessAction method. This method takes javax.portlet.ActionRequest and javax.portlet.ActionResponse parameters that you can use to process your action. Your *MVCActionCommand class should also contain any other code required to implement your action. For a real-world example of a *MVCActionCommand class, see the Blogs app’s EditEntryMVCActionCommand class.

Related Topics

MVC Render Command

MVC Resource Command

MVC Command Overrides