What is a smarter way to get a child control in XAML?

Question

I have a User Control, containing a Grid, containing a child control.

I want to get a reference to the child control from the code behind for the User Control.

This is what I have:

var childControl = (MyChildControlType)this.Grid.Children.Single(c => (string) c.GetValue(NameProperty) == "MyChildControlNameFromXAMLNameAttribute");

Ugly as a run over garbage can lid.

What is a neater way to do this?

Answer 1

You could either go with the name-hunting, along the lines of what's been suggested already:

var childControl = (MyChildControlType)this.Grid.FindName("MyChildControlNameEtc");

Or, if you wanted a more generic approach to what you're already trying (eg if you want to look up by a different property), you could try:

var childControl = (MyChildControlType)this.Grid.Children.OfType<FrameworkElement>().Single(f => f.Name == "Blah");

or

var childControl = (MyChildControlType)this.Grid.Children.OfType<MyChildControlType>().Single(f => f.Name == "Blah");

Or you could use the VisualTreeHelper, which would work with non-Grids, and would particularly work nicely if you needed to recurse down the visual tree:

for(int i = 0; i < VisualTreeHelper.GetChildrenCount(this.Grid); ++i)
{
    var child = VisualTreeHelper.GetChild(this.Grid, i) as FrameworkElement;
    if (child != null && child.Name == "Blah")
        return child;
}

But really if you can just name it and access it from the codebehind normally like what John Bowen said that's by far the easiest.

Answer 2

Assigning a Name or x:Name to an element in XAML (unless it is inside a template) makes that element accessible from code-behind as a field with that name. So this is basically already declared and populated for you during InitializeComponent:

MyChildControlType MyChildControlNameFromXAMLNameAttribute;

and you can use it directly:

MyChildControlNameFromXAMLNameAttribute.Visibility = Visibility.Hidden;

Answer 3

可能是这样，给您的childControl输入x：Name

 var childControl = (MyChildControlType)MyGridNameFromXAMLNameAttribute.FindName("MyChildControlNameFromXAMLNameAttribute");