Saturday, September 17, 2011

Applying Pageing and Sorting on ListBox Control

Background :
                    If you have ever used the data grid control then you are familiar with the sorting functionality which is provided by default, when you click any of the data grid header then it will sort the records according to the that column name on every click it will sort it ascending or descending direction. Similarly you are familiar with the data pager control which we often used with the data grid control to show record in the form of page which contain specific page size.It was one of the question which one of my colleague ask me "Can we apply paging to the List Box control ". As I didn't use data pager control other then data grid so in this post I have used the data page control and also the sorting which is provided by the PagedCollectionView.

                For this example I have the application which you can see in Image 1, Here you can see that I have used combo box control which is used to sort the list box control item in ascending or descending order, List box control to display the records and the data pager control for the paging purpose.

Image 1

The use of paging is very simple it is just same as you do with the data grid control. Just place the data pager control in the xaml and set the Source property of the data pager to the list or collection which is used to bind the list box control, here you can see if I remove the data pager control then it will display all the record of the collection/list as you can see in the Image 2. So paging is quite easy similar to the data grid paging.

Image 2
Second part which is used to sort the items in the list box control is easy as well but you need to do some coding for it. For this I have done some coding in the view model of the home page which you can see in the List 1 here you can see I have posted whole view model as it is small view model not very large amount of coding in it. In the code you can see I have only two properties one is the PersonList (which is of type PagedCollectionView type which is used too bind the list box control ) and second one is the SortDirection property of type string ( which is used to sort the list box item according to the one of the value either ascending  or descending which are display in the combo box as inline items ).

List 1

In the constructor I have populated the PersonList PagedCollectionView by calling GetPersonRecord function of the person class ( the person class has on one property , the name property which is of type string and hold the person name). The main functionality of the sorting is done in the SortDirection property where I have used the SortDescriptions property of the PagedCollectionView to sort the records in the List.SortDescriptions collection of PagedCollectionView describes how items are sorted in view. SortDescriptions is a collection in which we can add more than one sort field. But here in our example as I have only one field which is the name field so I have first clear the SortDescriptions and then add the new sort direction, if you have more then one direction to sort the record then you don't need to call the clear function of the SortDescriptions you just add the new field in that and it will perform the sorting according to the field name which are provided in the list.We add sort field by adding SortDescriptions that specify which property will be used for sorting and the direction(ascending or descending order). When user select Ascending from the combo box then item are sorted from A to Z direction which you can see in the Image 3.

Image 3
When user select Descending from the combo box then item are sorted out from Z to A direction which you can see in the Image 4.

Image 4
I have tried to used the paging and sorting in the list box control and also tried to explain you how you can used it in your code if you have requirement to sort the list box control, you can event it it without giving the control to you user like I have provided the combo box and provided two option ascending and descending. You can download the source code from here.

All and any comments / bugs / suggestions are welcomed!

1 comment:

sri said...

Excellent..Thankyou so much