Access to codebehind variable in XAML

Question

How can I access a public variable that is in the Sample.xaml.cs file, for example asp.net <%=VariableName%> ?

Answer 1

There are several ways to do this.

• Add your variable as a resource from codebehind:

   myWindow.Resources.Add("myResourceKey", myVariable); 

  Then you can access it from XAML:

   <TextBlock Text="{StaticResource myResourceKey}"/> 

  If you need to add it after XAML receives the parsing, you can use DynamicResource above instead of StaticResource .

• Make a variable a property of something in your XAML. This usually works through a DataContext :

   myWindow.DataContext = myVariable; 

  or

   myWindow.MyProperty = myVariable; 

  After that, something in your XAML can access it through Binding :

   <TextBlock Text="{Binding Path=PropertyOfMyVariable}"/> 

  or

   <TextBlock Text="{Binding ElementName=myWindow, Path=MyProperty}"/> 

Answer 2

For binding, if the DataContext not used, you can simply add this to the code constructor behind:

 this.DataContext = this; 

Using this, each property in the code becomes available for binding:

 <TextBlock Text="{Binding PropertyName}"/> 

Another way is to simply give the name to the root XAML element:

 x:Name="root" 

Since XAML is compiled as an incomplete code class, we can access each property by name:

 <TextBlock Text="{Binding ElementName="root" Path=PropertyName}"/> 

Note: access is available only for properties; not the fields. set; and get; or {Binding Mode = OneWay} . If OneWay binding is used, the underlying data must implement INotifyPropertyChanged.

Answer 3

For fast and dirty Windows in WPF, I prefer to bind the DataContext window to the window itself; all of this can be done in XAML.

Window1.xaml

 <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" DataContext="{Binding RelativeSource={RelativeSource self}}" Title="Window1" Height="300" Width="300"> <StackPanel> <TextBlock Text="{Binding Path=MyProperty1}" /> <TextBlock Text="{Binding Path=MyProperty2}" /> <Button Content="Set Property Values" Click="Button_Click" /> </StackPanel> </Window> 

Window1.xaml.cs

 public partial class Window1 : Window { public static readonly DependencyProperty MyProperty2Property = DependencyProperty.Register("MyProperty2", typeof(string), typeof(Window1), new UIPropertyMetadata(string.Empty)); public static readonly DependencyProperty MyProperty1Property = DependencyProperty.Register("MyProperty1", typeof(string), typeof(Window1), new UIPropertyMetadata(string.Empty)); public Window1() { InitializeComponent(); } public string MyProperty1 { get { return (string)GetValue(MyProperty1Property); } set { SetValue(MyProperty1Property, value); } } public string MyProperty2 { get { return (string)GetValue(MyProperty2Property); } set { SetValue(MyProperty2Property, value); } } private void Button_Click(object sender, RoutedEventArgs e) { // Set MyProperty1 and 2 this.MyProperty1 = "Hello"; this.MyProperty2 = "World"; } } 

In the above example, notice the binding used in the DataContext the window, it says: "Set your data context for yourself." Two text blocks are attached to MyProperty1 and MyProperty2 , the event handler for the button will set these values, which automatically apply to the Text property of two text blocks, since the properties are dependency properties.

Answer 4

It is also worth noting that the "binding" can only be set on the DependencyProperty of the DependencyObject. If you want to set the Non DependencyProperty property (for example, a normal property) for an object in XAML, then you will have to use the first method of using resources in the code for Robert.