v2013.2.1024 declarative binding an endless scrolling list view is broken

[Dean]

My endless scrolling listviews were working (excepting a couple of bugs that I've already brought up on this forum) until I updated to v2013.2.1024 and now I get the following error: 

"Uncaught Error: the DataSource does not have page size configured. Page Size setting is mandatory for the mobile listview virtual scrolling to work as expected."

I found that this only happens when I use declarative binding. This problem also occurs in the latest available beta v2013.3.1030.

Cheers
Dean

[Petyo]

Hi Dean,

This sounds like a bug we have introduced. Is it possible for you to share some sample code? We will look into it immediately. 

Regards,
Petyo
Telerik

[Dean]

I copied the endless-scrolling example and changed it to use declarative binding. You'll need to unzip and put the attached html file in the same directory so that the file paths for links and scripts work:
kendoui.mobile.[phone].commercial\examples\mobile\listview

While creating this example I noticed the problem is with:

data-bind="source: dataSource"

but this works:

data-source="dataSource"

Cheers
Dean

[Petyo]

Hello Dean,

Thank you for your example. I can confirm this problem - we will try to target this for our next official release, due later this month. Your telerik points have been updated. 

Regards,
Petyo
Telerik

[Dean]

I've just tried v2013.3.1119 and I am very disappointed to find this hasn't been addressed. I can't upgrade until it is fixed because I use declarative binding throughout my app.

[Petyo]

Hello Dean,

I am sorry for the inconvenience - we fixed a very similar case, but it looks like this one remains broken. We are going to resolve it in our upcoming internal builds, most probably by the end of this week. 

Regards,
Petyo
Telerik

[Brandon Peterson]

I am getting the same error when using MVVM binding although the DataSource pageSize property is set:
"the DataSource does not have page size configured. Page Size setting is mandatory for the mobile listview virtual scrolling to work as expected."

<div data-role="view" id="home" data-title="Home" data-model="vm">
    <ul data-role="listview" data-bind="source: albumList, click: itemClick" data-template="album-template" data-pull-to-refresh="true" data-endless-scroll="true"></ul>
    <script type="text/x-kendo-tmpl" id="album-template">
        <img data-bind="attr: { src: artwork }" />
        <div class="info">
            <h3 data-bind="text: title"></h3>
            <em data-bind="text: artist"></em>
        </div>
    </script>
</div>

http://jsfiddle.net/bYKYE/315/

If I use data-soure="vm.albumList" instead then I lose all MVVM template binding capabilities and have to modify like so:

<ul data-role="listview" data-source="vm.albumList" data-bind="click: itemClick" data-template="album-template" data-pull-to-refresh="true" data-endless-scroll="true"></ul>
    <script type="text/x-kendo-tmpl" id="album-template">
        <img src="#:artwork#" />
        <div class="info">
            <strong>#= title#</strong>
            <em>#= artist#</em>
        </div>
    </script>

http://jsfiddle.net/bYKYE/313/

I would prefer not to refactor my entire app to implement a workaround for this bug. Is there a plan to correct the issue in upcoming releases?

[Petyo]

Hi Brandon,

the fix I refer to is published as an internal build - please give it a try. 

On a side note, I do want to mention that using MVVM bindings with endless scrolling yields increased memory usage and affects performance in general. The effect is especially visible on a mobile device. 

Regards,
Petyo
Telerik

[Durendal]

This issue renders the demos in GitHub unusable against the latest KendoUI release.  This means that users cannot take advantage of the latest mobile widgets.

What are the plans to update the GitHub demos please.   New user like myself who cloned the demos as a base for our POCs are finding this out the hard way.

If the demos are not QA against the latest release, please consider removing them, or at least add a warning/disclaimer. This way, newbies do not end up investing efforts needlessly.  Thanks.

[Petyo]

Hello Durendal,

thank you for your feedback - indeed, the published demos are lagging behind our current release. We are looking into updating them, especially the ones which feature outdated practices. 

Regards,
Petyo
Telerik

[Brandon Peterson]

Petyo, Internal Build 2013.3.1220 is working well with data- attributes. Thank you for the performance tip as well.

MVVM binding does make sense though in item templates for my scenario where a listview item is selected and then edited in a detail view. Upon navigating back from the detail view to the listview view, the item has been updated "inline" without having to re-bind the listview and lose the scroll position. If there is a more performant method of rebinding, repainting, and maintaining listview scroll position I'd appreciate any suggestions.

[Alexander Valchev]

Hello Brandon,

If I understood correctly, you are binding the ListView because you do not want to loose the scroller position after edit changes are saved. The ListView Editing demo also uses detail view for editing the selected item however the scroll position is never lost. Could you please check it and let me know what I am missing?

Regards,
Alexander Valchev
Telerik

[Kelly]

I'm completely confused.  Is this still a bug or not? I'm getting the exact behavior reported by Brandon above.  I'm trying to implement endless scrolling and pull to refresh with code very similar to his.  I'm using the latest kit, and I still get this error.  I'm binding attributes in a template, which is crucial for my app.  If I use data-bind="source: blah" I get the error.  If I use data-source="fully.qualified.blah", there is no error, but I lose the attribute bindings.

If this won't work, I'll have to ditch the DataSource I'm using for no other reason than to implement endless scrolling.  I really like letting the user control refreshes and fetching with scrolling.  I don't want to clutter my interface with a bunch of "More" and "Refresh" buttons.  Are there any examples available for hooking into the listview scroller to implement one's own version of endless scrolling and pull to refresh?  A way to just provide my own pulltorefresh and fetchnextpage functions to the listview would be great.  I know they don't exist, but can anyone think of a way to jury-rig them?

Thanks,

Kelly

[Kelly]

Never mind!  I see that the Scroller is where the pull is implemented, so all the events I was asking about are already there ...perfect!  Thanks.