Issues with SelectedItem

[Gopinath]

 

I have a listbox defined in the xaml -

<telerik:RadListBox x:Name="CartLineItems" ItemsSource="{Binding LineItems}" SelectedItem="{Binding SelectedArticle, Mode=TwoWay}"
ItemTemplate="{StaticResource ConfectioneryDataTemplate}" VerticalAlignment="Stretch"
HorizontalAlignment="Stretch" Background="LightGray">
</telerik:RadListBox>

 

I frequently need to clear and repopulate the ItemsSource to refresh the Listbox. (LineItems is an observable collection). When I clear the collection, the SelectedItem is also cleared (visually). When I repopulate and set the SelectedItem object with data, there is no item in the ListBox which is selected. Below is the code -

private void RefreshLineItems()
{
    // Store the selected article for later use.
    LineItem selectedLineItem = null;
    if (SelectedArticle != null)
        selectedLineItem = SelectedArticle;

    // Clear all the line items.
    LineItems.Clear();
    // Iterate through the cart to re-populate LineItems and reset the selected article.
    if (ActiveCart != null)
    {
        foreach (LineItem lineItem in ActiveCart.lineItems)
        {
            LineItems.Add(lineItem);
        }
        if (selectedLineItem != null)
            SelectedArticle = ActiveCart.lineItems.Find(x => x.articleID == selectedLineItem.articleID);
    }
}

 

How do I get the selected item to re-appear on the listbox after the ItemsSource is cleared?

Thanks.

Gopinath

[Drago]

Hi Gopinath,

The way you can achieve that is by implementing the INotifyPropertyChanged interface and use the PropertyChanged event or have the telerik ViewModelBase class and use the OnPropertyChanged method.

We have created a sample project for you using ViewModelBase approach.

Please test to see if that helps and let me know.

Regards,
Dragan G
Progress Telerik

[Gopinath]

Hello Dragen,

Thanks for the sample project. I was able to fix the problem. 

Its crazy to assume that lot of things work straight forward, especially if you are switching over from frameworks like Angular, etc.

 

Regards,

Gopinath

[Sweidan]

Hi Drago!

I try to build the code example you provided, but I get the following error:

Could not resolve this reference. Could not locate the assembly "Telerik.Windows.Controls, Version=2019.2.618.40, Culture=neutral, PublicKeyToken=5803cfa389c90ce7, processorArchitecture=MSIL". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors.

Can I download the missing assembly, and add it to the project via NuGet package manager?

[Vladimir Stoyanov]

Hello Sweidan,

I am attaching the sample project updated with the necessary dll added so you can test it on your end. 

To answer your question, you can also download the UI for WPF dlls via NuGet. You can read some more about that in the Installing UI for WPF from a NuGet package article. 

I hope you find this helpful.

Regards,
Vladimir Stoyanov
Progress Telerik