从项目模板WPF中获取列表项目控件

Question

I bind my list View with user controls as below,

<ListView Grid.Row="2" Name="lvItems">
       <ListView.ItemTemplate>
                <DataTemplate>
                    <my1:ucItem Name="li"/>
                </DataTemplate>
            </ListView.ItemTemplate>
</ListView>

That user control has local storage value that user will input at run time. I don't want two way binding because, at run time that user control add another value other than user control is showing. I set up some get method to get back value stored in user control. How can I get back that user control, lvItems.Items is just return Object List I bind to it, not my User Control. Is there a way to get back that generated User Control List.

for example, i want to read back ListView Items like that,

foreach(UserControl uc in lvItems.Items){//Do Something}

Answer 1

@Amit is right in the comments, you should really use MVVM and a data binding approach. That said, if you are determined to do it the other way, this extension method should help:

public static class ItemsControlExtensions
{
    public static IEnumerable<TElement> GetElementsOfType<TElement>(
        this ItemsControl itemsControl, string named)
        where TElement : FrameworkElement
    {
        ItemContainerGenerator generator = itemsControl.ItemContainerGenerator;

        return
            from object item in itemsControl.Items
            let container = generator.ContainerFromItem(item)
            let element = GetDescendantByName(container as FrameworkElement, named)
            where element != null
            select (TElement) element;
    }

    static FrameworkElement GetDescendantByName(FrameworkElement element,
        string elementName)
    {
        if (element == null)
        {
            return null;
        }

        if (element.Name == elementName)
        {
            return element;
        }

        element.ApplyTemplate();

        FrameworkElement match = null;
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(element); i++)
        {
            var child = VisualTreeHelper.GetChild(element, i) as FrameworkElement;
            match = GetDescendantByName(child, elementName);

            if (match != null)
            {
                break;
            }
        }

        return match;
    }
}

Usage would be like this:

foreach (UserControl uc in lvItems.GetElementsOfType<UserControl>(named: "li"))
{
    // do something with 'uc'
}

The GetDescendantByName method is based on one by Dr WPF from this blog post: ItemsControl: 'G' is for Generator . In fact, that whole series of blog posts about how the ItemsControl works is well worth a read: Dr WPF: ItemsControl: A to Z .