Creating Entry List Screenlet's Interactor

Recall that Interactors are Screenlet components that make server calls and process the results. Also recall that Interactors themselves are made up of several components:

  1. The event class
  2. The listener interface
  3. The Interactor class

Since the list Screenlet framework already contains two listeners, you only need to create the event and Interactor classes. This article walks you through the steps required do this. Because Entry List Screenlet’s Interactor is so similar to that of Guestbook List Screenlet, these steps aren’t explained in detail. Focus is instead placed on the few places in the code where the Interactors diverge. For a full explanation of the code, see the article on creating Guestbook List Screenlet’s Interactor.

You’ll create the event class first.

Creating the Event Class

Recall that you must create an event class to communicate the server call’s results via EventBus. First, create a new package called interactor in the com.liferay.docs.entrylistscreenlet package. Then create the EntryEvent class in the interactor package. Replace this class’s contents with this code:

package com.liferay.docs.entrylistscreenlet.interactor;

import com.liferay.docs.model.EntryModel;
import com.liferay.mobile.screens.base.list.interactor.ListEvent;

public class EntryEvent extends ListEvent<EntryModel> {

    private EntryModel entry;

    public EntryEvent() {
        super();
    }

    public EntryEvent(EntryModel entry) {
        this.entry = entry;
    }

    @Override
    public String getListKey() {
        return entry.getMessage();
    }

    @Override
    public EntryModel getModel() {
        return entry;
    }
}

This code is almost identical to GuestbookEvent. The only difference is that it works with entries instead of guestbooks.

Next, you’ll create the Interactor class.

Creating the Interactor Class

Recall that an Interactor class issues the server call and processes the results via the event. In the interactor package, create a new class called EntryListInteractor. Replace this class’s content with this code:

package com.liferay.docs.entrylistscreenlet.interactor;

import com.liferay.docs.model.EntryModel;
import com.liferay.mobile.android.v62.entry.EntryService;
import com.liferay.mobile.screens.base.list.interactor.BaseListInteractor;
import com.liferay.mobile.screens.base.list.interactor.BaseListInteractorListener;
import com.liferay.mobile.screens.base.list.interactor.Query;

import org.json.JSONArray;
import java.util.Map;

public class EntryListInteractor extends
    BaseListInteractor<BaseListInteractorListener<EntryModel>, EntryEvent> {

    @Override
    protected JSONArray getPageRowsRequest(Query query, Object... args) throws Exception {

        long guestbookId = (long) args[0];
        return new EntryService(getSession()).getEntries(groupId, guestbookId, 
            query.getStartRow(), query.getEndRow());
    }

    @Override
    protected Integer getPageRowCountRequest(Object... args) throws Exception {

        long guestbookId = (long) args[0];
        return new EntryService(getSession()).getEntriesCount(groupId, guestbookId);
    }

    @Override
    protected EntryEvent createEntity(Map<String, Object> stringObjectMap) {
        EntryModel entry = new EntryModel(stringObjectMap);
        return new EntryEvent(entry);
    }

    @Override
    protected String getIdFromArgs(Object... args) {
        return String.valueOf(args[0]);
    }
}

Besides getting entries instead of guestbooks, this class is almost identical to GuestbookListInteractor. The only other differences are due to the service calls that retrieve the entries and number of entries from a guestbook in the Guestbook portlet. These service calls, made in getPageRowsRequest and getPageRowCountRequest, require an EntryService instance. The getEntries method retrieves a guestbook’s entries, and the getEntriesCount method retrieves the number of entries in a guestbook. Note that these calls require a guestbook ID (guestbookId) in addition to the group ID (groupId). The getPageRowsRequest and getPageRowCountRequest methods get the guestbookId from the args argument, and then use it along with groupId make their service calls. You’ll see how the guestbookId gets into the args argument when you create the Screenlet class.

Nicely done! Now that Entry List Screenlet has an Interactor, you must create the Screenlet class. The next article shows you how to do this.

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