Step through the code with the debugger and see if there is actually nothing retured or if the as -cast is just wrong and thus turns it to null you could just use a normal cast to get a proper exception. One problem that frequently occurs is that when an ItemsControl is virtualizing for most of the items no container will exist at any point in time.
Also i would not recommend dealing with the item containers directly but rather binding properties and subscribing to events via the ItemsControl. After trying many solutions suggesting to add IsExpanded and IsSelected to underlying object and binding to them in TreeViewItem style, while this mostly works in some case it still fails There are a few other minor differences between the ListBox and ListView controls What is The difference between ListBox and ListView - which should not essentially affect your use case.
See the below implementation. Which helps me to avoid the same issue. Set your application VirtualizingStackPanel. See the link for detailed info. For anyone still having issues with this, I was able to work around this issue by ignoring the first selection changed event and using a thread to basically repeat the call.
Here's what I ended up doing:. You can set whatever you need to null to trigger the first selection changed event and then return out of the event so that future events work as expected. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. ContainerFromItem returns null? Ask Question. Asked 10 years, 6 months ago.
Active 5 years, 11 months ago. Viewed 45k times. Any ideas? Here's the bit of code I'm using: this. Sonny Boy Sonny Boy 7, 17 17 gold badges 69 69 silver badges bronze badges.
Can't you just iterate through Items, which would be a readonly collection but its contents would not be readonly? I tried that, too. ContainerFromIndex also returns null. The following link contains its answer.
Add a comment. Active Oldest Votes. UpdateLayout ; dataGrid. ScrollIntoView dataGrid. ContainerFromIndex index ; If you don't want the current location in the DataGrid to change, this probably isn't a good solution for you but if that's OK, it works without having to turn off virtualizing. Community Bot 1 1 1 silver badge. Phred Menyhert Phred Menyhert 2, 4 4 gold badges 18 18 silver badges 19 19 bronze badges.
Thanks, this solved my problem. I was trying to set focus to an item that was not available yet. What does your custom ComboBox look like? And by the way, setting VirtualizingStackPanel. IsVirtualizing on a StackPanel also has no effect. I guess virtualization is not the problem here. ContainerFromItem item returns null when the dropdown is not opened thus not rendered. Is there a way to get the item before the dropdown is rendered — Berker Soyluoglu.
When does your ItemContainerGenerator. ContainerFromItem get run? You may need to be sure that the containers have been generated first. Also, if you don't cast it as a ComboBoxItem , does it return a value? ContainerFromItem might just return your template in a ContentPresenter , which gets later wrapped in a ComboBoxItem , so its possible the cast is simply invalid which is why you're getting null — Rachel.
Show 1 more comment. Active Oldest Votes. Titov R. Titov 2, 27 27 silver badges 31 31 bronze badges. I lost a whole hour on the problem trying different suggestions and this answer helped me!
Add a comment. Use ItemContainerGenerator. Michel P. Sign up or log in Sign up using Google. Hi smartgl78, I think this could be a timing issue.
Please try the following code. Reply to Min Zhu : Hi Min Zhu, you are right it's a timing issue, but the example that you gave, it didn't work. LayoutUpdated event solved the problem. I marked HomeroThompson reply as an answer because he gave me the link to an example that its idea solved my problem and it emphasized that the problem is the wrong timing, but I didn't like the solution, so I tried to find a way to solve this problem, I found.
Thanks a lot for your efforts. Thursday, August 18, PM. Hello, Does lbProjectsList. Could you check it please? ContainerFromItem item ; lbitem also will be null. Thanks a lot Homero, It worked for me also. Best Regards. Edited by smartgl78 Thursday, August 18, PM. Hi Dimitar, I will try your suggestion when I will return at home, I'm work now. I will give the result of the test as soon as I return at home.
Thank you. Wednesday, August 17, AM. Hi Smart, This problem could be caused due to Virtualization. Regards, Parth Shah. Proposed as answer by parth. Hi Dimitar, I tried your suggestion and the result is the same, it returns null.
Wednesday, August 17, PM. Hi Parth.
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