Paging Data

[Manuel Felício]

Hi,

Is there any data pager or UI guideline with data pagination?

I know I could gather more data as the user scrolls down the screen but I don't really like scrolling thousands of records in the same screen.

I was thinking in using a control like the Pivot control where the user would slide to the next or the previous page.

What are your thoughts about this?

Best regards,
Manuel Felício

[Deyan]

Hello Manuel,

Currently we do not have an out-of-the-box solution for this scenario since, as an approach, it is not so popular in the context of Windows Phone 7. Also, I cannot give an estimation of whether we are going to build similar component and when it could be available.

In general we think that having thousands of data items loaded on the phone is not a good idea both in terms of user experience and memory consumption. If you have thousands of data items neither paging, nor scrolling will bring a pleasant experience to your users since - in either way - they will have to make their way through it (no matter whether they scroll or switch between pages with the same flick gesture) - which, as far as I understand - you would like to avoid.

Our advice is to filter your data so that the most relevant information is downloaded by your app and thus avoid having to handle large amounts of information.

I hope this helps.

Do not hesitate to get back to us in case you have further questions or need assistance.

Greetings,
Deyan
the Telerik team

[Manuel Felício]

I can't select the most relevant data to show. I have to show all items available, but I need to paginate those items.

Is it official that Telerik hasn't thought yet how to do pagination of hundreds of items for WP7?

I'm not asking for a data pager control, I'm just asking for some tips on what would be the recommended way to achieve this.

I also don't have a WP7 device yet, so I can't search for marketplace applications that display a lot of data and see how they are displaying paged items.

Best regards,
MF.

[Deyan]

Hi Manuel,

We have officially announced and recently releazed a beta version of a couple of data virtualization approaches in the context of RadDataBoundListBox which help handle large amounts of data. You can read about them here:

Data Virtualization Overview

These are the most popular and well accepted ways of handling long lists of data items.

For instance, by using the OnDemandManual approach you can implement a paging scenario by simply downloading the separate data chunks and instead of aggregating them in the source bound to the list box, load them separately. I have implemented a sample project which demonstrates the approach I am talking about.

I am using three different data templates which contain a previous, next and previous - next buttons. I am swapping them based on the data page I am currently at (if I cannot go back I only show the next button etc.). These data templates are set to the DataVirtualizationItemTemplate property which is used in the context of the OnDemandManual data virtualization mode.

Take a look at the sample project I am attaching for further details

I hope this helps.

Regards,
Deyan
the Telerik team

[Manuel Felício]

Hello Deyan,

Thank you for your response. It was very useful and I'm finally seeing the light!

I was thinking about a more userfriendly paginator. What do you think of using the RadJumpList and whenever I load more items, say move to another page, I create an header with the number of the page. That would allow the user to scroll between pages relatively fast and still have a button at the bottom of the listbox to load more items, if there are any left to load.

I'm not asking you to implement this, unless you think it is useful for WP7 RadControls, I'm just asking if you agree that users would accept this way of paging data for wp7.

Another question I have, if I keep appending items to the end of the list and create headers (to use with RadJumpList) and I have 1000 items loaded, do you still virtualize the listboxitems?

Best regards,
Manuel Felício.

[Deyan]

Hi Manuel,

Thanks for writing back.

Our RadJumpList control is suitable for this scenario. You can actually load a predefined set of GroupPickerItems which are displayed when you tap on a group header within the jump list. You can basically load as much group picker items as needed and when the user taps on one of them, simply see which page has been selected and load the desired items. Here is a help article from our online help that gives a hint on how you can load custom group picker items within the RadJumpList:

http://www.telerik.com/help/windows-phone/radjumplist-features-group-picker.html

Actually, there are a bunch of approaches you can use to implement similar scenarios. It depends on the UX design of your application, i.e. the way you would like to make your end-users experience it. Many of the applications on the Windows Phone 7 Marketplace, even the Marketplace App itself, use the approach of eventually appending items at the end of the list when the user reaches it.

I hope this is helpful.

Best wishes,
Deyan
the Telerik team

[Manuel Felício]

Hi,

I already implemented the technique I mentioned above and it is working like a charm.

I'm using OnDemandManual for virtualization and whenever the user presses a button on the bottom of the results I load more items and create a new group on the RadJumpList saying "Records from X to Y", allowing the user to jump from one "page" to another.

Thanks for all the help.

Best regards,
Manuel Felício.