有没有办法在ListBox Items模板中进行迭代? [英] Is there a way to iterate in a ListBox Items templates?

问题描述

我有一个列表框，其中包含由单个文本框表示的项目.

I have a list box that contains items that are represented by a single textbox.

当用户单击按钮时，我要遍历所有这些文本框，并检查它们的绑定表达式中是否包含错误； 应该是这样的:

When the user clicks a button, I want to iterate thru all these text boxes and check if their binding expressions are clean of errors; Should be something like:

    Dim errCount = 0
    For Each item In MyListBox.ListBoxItems 'There is no such thing ListBoxItems which is actually what I am looking for.
        Dim tb As TextBox = item '.........Dig in item to extract the textbox from the visual tree.
        errCount += tb.GetBindingExpression(TextBox.TextProperty).HasError
    Next
    If errCount Then
        'Errors found!
    End If

任何讨论将不胜感激. 谢谢.

Any discussion would be really appreciated. Thanks.

推荐答案

可能有更简单的方法，但这是一个可行的选择:

There may be an easier way to do this, but here is one option that will work:

1)遍历项目列表.

因为您正在使用项目源，所以ListBox.Items将引用ItemsSource中的数据项目.

Because you are using items source, ListBox.Items will refer to the data items in the ItemsSource.

for (int i = 0; i < ListBox.Items.Count; i++)
{
    // do work as follows below...
}

2)获取这些物品的容器.

2) Get the containers for these items.

DependencyObject obj = ListBox.ItemContainerGenerator.ContainerFromIndex(i);

3)使用VisualTreeHelper搜索容器视觉的TextBox子级.

3) Use VisualTreeHelper to search for a TextBox child of the container visual.

TextBox box = FindVisualChild<TextBox>(obj);

使用此功能搜索正确类型的可视孩子:

Use this function to search for a visual child of the correct type:

public static childItem FindVisualChild<childItem>(DependencyObject obj)
    where childItem : DependencyObject
{
    // Search immediate children
    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
    {
        DependencyObject child = VisualTreeHelper.GetChild(obj, i);

        if (child is childItem)
            return (childItem)child;

        else
        {
            childItem childOfChild = FindVisualChild<childItem>(child);

            if (childOfChild != null)
                return childOfChild;
        }
    }

    return null;
}

4)最后，检查TextBox上的绑定.

4) Finally, examine the binding on the TextBox.

全部放在一起，像这样:

All put together, something like this:

private bool ValidateList(ListBox lb)
{
    for (int i = 0; i < lb.Items.Count; i++)
    {
        DependencyObject obj = lb.ItemContainerGenerator.ContainerFromIndex(i);
        TextBox box = FindVisualChild<TextBox>(obj);
        if (!TestBinding(box))
            return false;
    }

    return true;
}

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