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FindVisualChild cannot find Grid in DataTemplate

I am trying to use a basic implementation of "FindVisualChild" for WPF in order to find a specific Grid that exists within a DataTemplate of a ListBox.
The implementation is as follows:
private DependencyObject FindVisualChild<T>(DependencyObject obj, string name)
{
Console.WriteLine(((FrameworkElement)obj).Name);
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(obj, i);
FrameworkElement fe = child as FrameworkElement;
//not a framework element or is null
if (fe == null) return null;
if(!string.IsNullOrEmpty(fe.Name))
Console.WriteLine(fe.Name);
if (child is T && fe.Name.Equals(name, StringComparison.CurrentCultureIgnoreCase))
return child;
else
{
//Not found it - search children
DependencyObject nextLevel = FindVisualChild<T>(child, name);
if (nextLevel != null)
return nextLevel;
}
}
return null;
}
My issue is that this code was working yesterday to find a Grid that I have defined in the DataTemplate with the name "MainTermServListGrid" as shown here:
<ListBox HorizontalAlignment="Stretch" Grid.Row="1" x:Name="TermServListBox" ItemsSource="{Binding TermServs}">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid x:Name="MainTermServListGrid">
//code here
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
However, today when I try to use the same method to find that Grid, the result is always null. If I debug and step through the code, it looks like it is not even finding any of the items that exist within the DataTemplate.
I am calling the FindVisualChild method right after I populate the ListBox with items. Could it be that I am not waiting long enough and the window does not have enough time to finish initializing and presenting the new items in the list box before I am trying to find a specific child within that listbox?
If that is the case, would a simple call to await Task.Delay(500) work to give the UI enough time to finish loading? Or am I doing something totally wrong here?

Turns out I was right in assuming I was not giving the UI enough time to finish loading. I believe it is due to the fact that I was populating the ListBox with items using a particular method, and at the end of that method I was raising an Event which triggered the search in the Window's code-behind.
Because there was never a period if time between finishing the loading of the items and the event being raised to look for them, I dont think the ui had time to finish initializing everything.
Basically all I did to fix the issue in my event handler was the following:
private async void ViewModelOnListPopulated(object sender, EventArgs eventArgs)
{
await Task.Delay(500);
//Continue on to find the visual child...
}

how to access a child element dynamically in WPF

In WPF, I have a structure like this
<Button>
<Grid>
<!--definitions for 1 row and 2 columns-->
<TextBlock x:Name="t1" Grid.Column="0"/>
<TextBlock x:Name="t2" Grid.Column="1"/>
</Grid>
</Button>
Supposed a Button b with this structure is generated dynamically. How to access t1 from Button b?
Edit for clarification: Since t1 resides within Button b, is it possible to change the content of t1 if one only have access to b? something along the line of b.childGridElement.childTextBlock_t1.Text = "newString"?

This should work for the use case you've provided:
((TextBlock)b.FindName("t1")).Text = "newString";

You need to use Visual Tree Helper for this.
Define Handler Extension Method
public static IEnumerable<T> FindVisualChildren<T>(DependencyObject parent) where T : DependencyObject
{
if (parent != null)
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
// If the available child is not null and is of required Type<T> then return with this child else continue this loop
if (child != null && child is T)
{
yield return (T)child;
}
foreach (T childOfChild in FindVisualChildren<T>(child))
{
yield return childOfChild;
}
}
}
}
now in your xaml
IEnumerable<TextBlock> textblockes=FindVisualChildren<TextBlock>(b);
foreach (var textblock in textblockes)
{
if (textblock!= null && textblock.Name="t1")
{
//write code for t1 here;
}
if (textblock!= null && textblock.Name="t2")
{
//write code for t2 here;
}
}
In above method whatever is your tree structure , it will find all the textblock of your Button b and then on the basis of Name property you can do appropriate operations.

Is there a way to get values of child elements from DataTemplate? (WP8)

For example, I have a ItemsControl with a custom DataTemplate:
<ItemsControl Name="CategoriesList">
<ItemsControl.ItemTemplate>
<DataTemplate>
<CheckBox Content="{Binding}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
For example my collection contains 100 elements. I want to get which CheckBoxes is checked and which is not or I just want to change a Content property. In both cases I need to get a CheckBox element from code. So it's easy to get Items from code:
var cList = CategoriesList.Items;
foreach (var item in cList)
{
//Do Something
}
But I need to get CheckBoxes from these items. Is it possible?
Thank you!

You need to use a visual tree helper for the same
I have tried it with a listbox and it works! Ant I think the same would work for an ItemsControl as well because the properties and methods of a listbox and an ItemsControl are same.
Just make and use this Method to dig inside the visual tree of a listbox
public static T FindFirstElementInVisualTree<T>(DependencyObject parentElement) where T : DependencyObject
{
try
{
int childCount = VisualTreeHelper.GetChildrenCount(parentElement);
if (childCount == 0)
return null;
for (int i = 0; i < childCount; i++)
{
var child = VisualTreeHelper.GetChild(parentElement, i);
if (child != null && child is T)
{
return (T)child;
}
else
{
var result = FindFirstElementInVisualTree<T>(child);
if (result != null)
return result;
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
return null;
}
And that's how you are going to use this method in code
ListBoxItem SelectedListBoxItem = this.lstInstagramTags.ItemContainerGenerator.ContainerFromIndex(int index) as ListBoxItem;
if (SelectedListBoxItem == null)
return;
// Iterate whole listbox tree and search for this items
Button btn= FindFirstElementInVisualTree<Button>(SelectedListBoxItem );
btn.Content="Hello";
And a Link too
Hope this helps.

Visual and Logical tree traversal does not retrieve several levels

I'm exploring logical and visual trees from the same application without success going deeper through the levels.
My code uses a generic explorer:
private static void ProcessGenericTree(object current, List<FrameworkElement> leaves, Type treeType)
{
if (current is FrameworkElement)
{
if (!leaves.Contains(current as FrameworkElement))
leaves.Add(current as FrameworkElement);
}
DependencyObject dependencyObject = current as DependencyObject;
if (dependencyObject != null)
{
if (treeType.Equals(typeof(VisualTreeHelper)))
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(dependencyObject); i++)
{
ProcessVisualTree(VisualTreeHelper.GetChild(dependencyObject, i), leaves);
}
}
else
{
foreach (object child in LogicalTreeHelper.GetChildren(dependencyObject))
{
ProcessLogicalTree(child, leaves);
}
}
}
}
ProcessLogicalTree and ProcessVisualTree simply iterate (doing something before the ProcessGenericTree re-call).
The result looks complete, but when I'm trying to retrieve a TextBlock into a GridViewColumn Header it looks like the item doesn't exist neither in the Logical nor in the Visual leaves list of FrameworkElement.
It seems to be a Visual Element into a Logical Element. In fact adding a watch this TextBlock appears in the Visual Children of my GridView (retrieved as logical, it stands in a Tab Item not selected), but my code isn't unable to get it.
My call is pretty simple:
ProcessVisualTree(root, _visualElements);
ProcessLogicalTree(root, _logicalElements);
where root is the MainWindow.
So, how can I explore my tree at its deepest level? Maybe re-iterating through the retrieved FrameworkElement list? I think my ProcessGeneric code already does it.
Update: the WPF Visualizer shows a structure of this kind:
ListView > ScrollViewer > Grid > DockPanel > Grid > ScrollContentPresenter > GridViewHeaderRowPresenter > GridViewColumnHeader > HeaderBorder
The GridViewColumnHeader level contains my TextBlock but the visual tree doesn't.
Update 2: using the recursion starting from the main window with my element visible I'm not able to Find the object with a specified name with this code:
public static T FindVisualChild<T>(DependencyObject depObj) where T : DependencyObject
{
if (depObj != null)
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
if (child != null && child is T)
{
return (T)child;
}
T childItem = FindVisualChild<T>(child);
if (childItem != null) return childItem;
}
}
return null;
}
I'm pretty sure the VisualTreeHelper is not able to retrieve elements inside Header property but the WPF Inspector works correctly.
I wonder if it uses a different approach to traverse the tree (maybe inspecting the Properties like Header too). Suggestions?

How to set a clr-namespace property programatically in WPF

I am new with WPF, so I'm not sure if the title of the question is correct or makes any sense, please edit if it can get more relevant. I am using Kinect.Toolbox MouseControl in my application. For using the magnetic controls I have a problem. I know that I can define them in XAML by adding:
<Page ...
xmlns:local ="clr-namespace:Kinect.Toolbox;assembly=Kinect.Toolbox">
...
<Button local:MagneticPropertyHolder.IsMagnetic="True" ... />
....
But I need to do it in the code. Is there anyway to set the magnetic controls in the code? I can get all the controlls in the page like this:
public static IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) where T : DependencyObject
{
if (depObj != null)
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
if (child != null && child is T)
{
yield return (T)child;
}
foreach (T childOfChild in FindVisualChildren<T>(child))
{
yield return childOfChild;
}
}
}
}
foreach (Button tb in FindVisualChildren<Button>(this))
{
//Set the buttons to be magnetic
}
However I cannot understand how to set them progmatically.

This looks like an attached property.
To set it, you'd do something like
tb.SetValue(MagneticPropertyHolder.IsMagneticProperty, true);
or possibly
MagneticPropertyHolder.SetIsMagnetic(tb, true);
A quick glance at the Kinect Toolbox source code suggests that either would work. The second is more type safe.
See How to I access an attached property in code behind? for more information.