Picker in listview

hadeel

hi, everyone,
I face the following problem,
My app is simple, there is a listview contains 10 items each item contains picker and label,
and I have a save button at the end of the page
when clicking a button I need to collect data that is selected from each picker in the list
the problem is that when I scroll the list down NullReferenceException appears

I don't find a way to solve it
can anybody help, please?

the picture attached describes the problem.

any help, Please!

Yelinzh

@hadeel I've tested a basic demo and it works as except. The selectedItem of Picker should be convert to the model class type instead of a property, try to change the code like follow.

private void OnPickerSelectedIndexChanged(object sender, System.EventArgs e)
{
    var item = (Picker)sender;
    var selectedItemDegree = item.SelectedItem as PickerItem;

    int value = selectedItemDegree.value;
}

hadeel

@Jarvan
can you show me your full demo code Please?
I try to change the code as you tell me but the problem still exists

Yelinzh

@hadeel Here is the demo file you can refer to.

hadeel

@Jarvan thank you so much.
I think that there is another reason for that which is the ListView performance,
so I removed the following property from listview tag in my XAML code
CachingStrategy="RecycleElement"
then it works fine.

Yelinzh

@hadeel I've tested a basic demo and it works as except. The selectedItem of Picker should be convert to the model class type instead of a property, try to change the code like follow.

private void OnPickerSelectedIndexChanged(object sender, System.EventArgs e)
{
    var item = (Picker)sender;
    var selectedItemDegree = item.SelectedItem as PickerItem;

    int value = selectedItemDegree.value;
}

hadeel

@Jarvan
can you show me your full demo code Please?
I try to change the code as you tell me but the problem still exists

Yelinzh

@hadeel Here is the demo file you can refer to.

hadeel

@Jarvan thank you so much.
I think that there is another reason for that which is the ListView performance,
so I removed the following property from listview tag in my XAML code
CachingStrategy="RecycleElement"
then it works fine.