Creating the iOS List Screenlet's Connector

Recall that Connectors make a server call. To support pagination, a List Screenlet’s Connector class must extend the PaginationLiferayConnector class. The Connector class must also contain any properties it needs to make the server call, and an initializer that sets them. To support pagination, the initializer must also contain the following arguments, which you’ll pass to the superclass initializer:

• startRow: The number representing the page’s first row.
• endRow: The number representing the page’s last row.
• computeRowCount: Whether to call the Connector’s doAddRowCountServiceCall method (you’ll learn about this method shortly).

For example, Bookmark List Screenlet must retrieve bookmarks from a Bookmarks portlet folder in a specific site. The Screenlet’s Connector class must therefore have properties for the groupId (site ID) and folderId (Bookmarks folder ID), and an initializer that sets them. The initializer also calls the superclass initializer with the startRow, endRow, and computeRowCount arguments:

import UIKit
import LiferayScreens

public class BookmarkListPageLiferayConnector: PaginationLiferayConnector {

    public let groupId: Int64
    public let folderId: Int64

    //MARK: Initializer

    public init(startRow: Int, endRow: Int, computeRowCount: Bool, groupId: Int64, 
        folderId: Int64) {
        
            self.groupId = groupId
            self.folderId = folderId

            super.init(startRow: startRow, endRow: endRow, computeRowCount: computeRowCount)
    }
    ...

Next, if you want to validate any of your Screenlet’s properties, override the validateData method as described in the tutorial on creating Connectors. Note that Bookmark List Screenlet only needs to validate the folderId:

override public func validateData() -> ValidationError? {
    let error = super.validateData()

    if error == nil {
        if folderId <= 0 {
            return ValidationError("Undefined folderId")
        }
    }

    return error
}

Lastly, you must override the following two methods in the Connector class:

• doAddPageRowsServiceCall: calls the Liferay Mobile SDK service method that retrieves a page of entities. The doAddPageRowsServiceCall method’s startRow and endRow arguments specify the page’s first and last entities, respectively. Make the service call as you would in any Screenlet. For example, the doAddPageRowsServiceCall method in BookmarkListPageLiferayConnector calls the service’s getEntriesWithGroupId method to retrieve a page of bookmarks from the folder specified by folderId:

    public override func doAddPageRowsServiceCall(session session: LRBatchSession, 
        startRow: Int, endRow: Int, obc: LRJSONObjectWrapper?) {
            let service = LRBookmarksEntryService_v7(session: session)
  
        do {
            try service.getEntriesWithGroupId(groupId,
                                              folderId: folderId,
                                              start: Int32(startRow),
                                              end: Int32(endRow))
        }
        catch  {
            // ignore error: the service method returns nil because
            // the request is sent later, in batch
        }
    }
  

  Note that you don’t need to do anything in the catch statement because the request is sent later, in batch. The session type LRBatchSession handles this for you. You’ll receive the request’s results elsewhere, once the request completes.

• doAddRowCountServiceCall: calls the Liferay Mobile SDK service method that retrieves the total number of entities. This supports pagination. Make the service call as you would in any Screenlet. For example, the doAddRowCountServiceCall in BookmarkListPageLiferayConnector calls the service’s getEntriesCountWithGroupId method to retrieve the total number of bookmarks in the folder specified by folderId:

    override public func doAddRowCountServiceCall(session session: LRBatchSession) {
        let service = LRBookmarksEntryService_v7(session: session)
  
        do {
            try service.getEntriesCountWithGroupId(groupId, folderId: folderId)
        }
        catch  {
            // ignore error: the service method returns nil because
            // the request is sent later, in batch
        }
    }
  

Now that you have your Connector class, you’re ready to create the Interactor.

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