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I need to do some kind of data validation in a WPF application I am developing

As far as I know, when you add ValidatesOnDataErrors=True to the Binding, everytime the Binding is resolved (it can be every time teh value changes, it can be when focus is lost), Binding engine checks the binding source, through IDataErrorInfo, access the interface, finds out if there is some error or not.

It sounds good, with only one caveat. In order for data to be validated, it needs to be rendered. If you happen to have an ObservableCollection of that entity bound to a ListBox with VirtualizingStackPanel.IsVirtualizing=True, only rendered items are validated. Since most items are outside viewport, they are not rendered.

How can I force every item to be validated? Removing UI virtualization is not an option.

Mutix
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Tio Luiso
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1 Answers1

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I have found one way to do so. It's ugly. But it works. Assuming the UI virtualized list is myList

for (Int32 i = 0; i < myList.Items.Count; i++)
{
     myList.ScrollIntoView(myList.Items[i]);
}
UpdateLayout();

That way, I get a list of all items. I scroll the list to every item in that list. And I update layout, because ScrollIntoView is asynchronous, I think. After that, every item has been rendered, every binding has been executed and every validation has been evaluated.

Are there better ways out there?

Tio Luiso
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