Implementing the Undo Functionality

Sometimes, users accidentally send the wrong entry to the Recycle Bin. It seems kind of grueling to navigate away from your page to the Recycle Bin to restore the item, just to go back to where you originally started, right? For this reason, the Recycle Bin framework supports an Undo button, so you can conveniently undo the action of sending an entry to the Recycle Bin without leaving the page.

Figure 1: Implementing the Undo button enables users to conveniently retrieve entries back from the Recycle Bin.

Walk through the following steps to implement the Undo functionality:

1. Add the Undo Tag
2. Call the Action for Restoration
3. Display the liferay-ui:trash-undo Tag

Go ahead and implement the Undo button and its related links!

Step 1: Add the Undo Tag

First, you must use the liferay-ui:trash-undo tag in your JSP. Then you need to set a portlet action URL and pass it to the liferay-ui:trash-undo tag. This maps the tag’s Undo button to the portlet action that you’ll implement in the next step.

The tags you add to your JSP should look similar to these tags for restoring a song in the Jukebox portlet:

<portlet:actionURL name="restoreSong" var="undoTrashURL" />

<liferay-ui:trash-undo portletURL="<%= undoTrashURL %>" />

Now that you’ve added the tag and action URL, go ahead and implement the portlet action to restore the entry.

Step 2: Create a Portlet Action to Initiate Restoration

You must create a portlet action method that invokes your service method to restore the entry.

For example, the following portlet action method from the JukeboxPortlet class restores songs from the Recycle Bin:

public void restoreSong(ActionRequest request, ActionResponse response)
    throws Exception {

    long[] restoreEntryIds = StringUtil.split(
        ParamUtil.getString(request, "restoreEntryIds"), 0L);

    for (long restoreEntryId : restoreEntryIds) {
        SongServiceUtil.restoreSongFromTrash(restoreEntryId);
    }
}

This method implements the restoreSong action that was named in the view.jsp. The action URL maps the liferay-ui:trash-undo tag to this method.

Note how it parses entry IDs from the request object. It restores all of these entries by calling the restore* service method.

Are you wondering how this portlet action gets the IDs of the entries to restore? You’ll learn how to pass this data to the session next.

Step 3: Providing Trash Entry Data for the Taglib

The final step for implementing the Undo button is to provide the trashed entry’s information to the liferay-ui:trash-undo tag. In order for the tag to display properly, you must provide some information for the session messages. The session needs to know which entries were just deleted. Then the restore method can use that information to restore the entries.

For example, the following if block from the JukeboxPortlet’s method deleteSong populates the session with the entries that were just deleted:

if (moveToTrash) {
    Song song = SongServiceUtil.moveSongToTrash(songId);

    Map<String, String[]> data = new HashMap<String, String[]>();

    data.put("deleteEntryClassName",
        new String[] {Song.class.getName()});
    data.put("deleteEntryTitle",
        new String[] {TrashUtil.getOriginalTitle(song.getName())});
    data.put("restoreEntryIds",
        new String[] {String.valueOf(songId)});

    SessionMessages.add(request, PortalUtil.getPortletId(request) +
        SessionMessages.KEY_SUFFIX_DELETE_SUCCESS_DATA, data);

    SessionMessages.add(request, PortalUtil.getPortletId(request) +
        SessionMessages.KEY_SUFFIX_HIDE_DEFAULT_SUCCESS_MESSAGE);
}

It gathers the elements needed to distinguish the entry instances to restore. For the Jukebox song elements, the song’s class name, title, and IDs are included.

data.put("deleteEntryClassName",
    new String[] {Song.class.getName()});
data.put("deleteEntryTitle",
    new String[] {TrashUtil.getOriginalTitle(song.getName())});
data.put("restoreEntryIds",
    new String[] {String.valueOf(songId)});

Then these elements are added to the session messages, so they appear in the portlet when it refreshes.

SessionMessages.add(request, PortalUtil.getPortletId(request) +
    SessionMessages.KEY_SUFFIX_DELETE_SUCCESS_DATA, data);

SessionMessages.add(request, PortalUtil.getPortletId(request) +
    SessionMessages.KEY_SUFFIX_HIDE_DEFAULT_SUCCESS_MESSAGE);

In your portlet’s delete action, you can similarly populate the session with the entry information of the entries being deleted. Now you know how to implement the Undo functionality for your app’s trash-enabled entities!

Related Topics

Recycling Assets with the Recycle Bin

Service Builder and Services

Enabling Search and Indexing

Asset Framework

Asset Enabling Custom Entities