Thursday, December 27, 2012

Sencha Touch List Paging with Memory Store


Recently I was working with Sencha Touch, Phonegap application. Where we have sqlite database as a local storage and we have number of lists where we displayed records from different tables. In some tables we were having more than 300 records and for the better performance and user experience we want to have paging in list.

Sencha list does support paging with list paging plugin. It's like you have to configure your list store with page size. So when you reach at end of the list store will be loaded again and it will again call url mentioned in your proxy and pass page number as param. But here in our case we have local database. So we were not having any ajax proxy where we can send page params and get next page data. Instead we have to write a db logic to get certain range of records. How to do that. First we extended list and added currentPage as config in it and it's initialized with 1.

Now the problem is we have to detect that user has scrolled till the end of the list so we can load next page data in list along with other data. This is the same logic used by list paging plugin. Check the following code.

         initialize: function(list){
                var scroller = list.getScrollable().getScroller();
                        scrollend: function(scroller, x, y){
                                if (y >= scroller.maxPosition.y) {
                                       //scrolled till end.
                                       //logic to get next records from database.
                       scope: this

Above code you need to add in your contoller's this.control method. The logic is quite simple. We added scroll end listener for list scrollbar and checked it's postion. If scroller's y coordinate matches scrollbar's max postion, that means we are at end. So here we have to write our logic to get next set of data from database. 

Hope this helps you. 


  1. When Back and Return 'initialize' doesnot fire, any idea how to fix it?