Do I have to implement IQueryable in order to use VirtualQueryableCollectionView effectively?

[Joshua]

Hi, I have a very large collection that would not fit into local memory very well, and I was trying to make use of the VirtualQueryableCollectionView telerik class.  It takes an IEnumerable, but if I pass in an IEnumerable it loops through all items in order to get the initial Count().  I looked at https://www.telerik.com/blogs/data-virtualization-for-your-silverlight-and-wpf-applications and downloaded the example application, but under the hood it's using something called an .edmx which I'm not familiar with.

What I want to do is to fetch the data on-the-fly.  I tried implementing an IList and passing it to VirtualQueryableCollectionView but that didn't seem to work either.  I'm familiar with how WPF Datagrids handle virtualization and paging, (https://www.codeproject.com/Articles/34405/WPF-Data-Virtualization) and have used that before, but I'm not sure how to do it with a Telerik RadGridView.  Can you point me in the right direction?  I'd use the paging control except I want the user to be able to just scroll down.

[Yoan]

Hi Joshua,

The .edmx file is part of the EntityFramework with which the mentioned demo is built. However, this is the important part of it:

var query = context.Order_Details.OrderBy(o => o.OrderID);

           var view = new VirtualQueryableCollectionView(query) { LoadSize = 10 };

the "query" is IQueryable and it is pass to the VQCV. So, you can just create your IQueryable and pass it as a source of the VQCV and this should be sufficient for populating the GridView. I must mention that using IQueryable is recommended if you will perform Filtering operations as stated in the Using Data Virtualization help article.

Please give this a try and let us know if you need further assistance.

Regards,
Yoan
Progress Telerik