In MainWindowxaml, replace the grid with one that defines a double in C#

Generation Code 39 Full ASCII in C# In MainWindowxaml, replace the grid with one that defines a double

column and single row grid Then add a label in each grid cell, like this:

<Grid> <GridColumnDefinitions> <ColumnDefinition></ColumnDefinition> <ColumnDefinition></ColumnDefinition> </GridColumnDefinitions> <GridRowDefinitions> <RowDefinition></RowDefinition> </GridRowDefinitions> <Label x:Name= lblCarMake GridRow= 0 GridColumn= 0 Content= {Binding Path=Make, Mode=OneTime} /> <Label x:Name= lblCarModel GridRow= 0 GridColumn= 1 Content= {Binding Path=Model, Mode=OneTime} /> </Grid>

Take a look at the Content dependency property value The information contained within the curly braces defines the binding for the content to be displayed in the labels I describe what this Binding expression means in just a moment, but first, let s get some data to bind to!

method called GenerateData that instantiates a Car object and assigns it to the DataContext of the window, like this:

private void GenerateData() { Car car1 = new Car() { Make = Athlon , Model = XYZ }; thisDataContext = car1; }

DataContext defines the root object relative to which all child elements obtain their values (as long as the DataContext value on the child elements is not directly set via XAML or code this property is an example of property value inheritance; its value is obtained from its parent element unless otherwise specified)

5 Call the GenerateData() method in the MainWindow constructor method (public MainWindow()), immediately following InitializeComponents() call Now, looking back to the XAML file (MainWindowxaml), the first label lblCarMake will bind to the DataContext s Make property The value is retrieved from the property specified in the binding s Path

component Similarly, the second label lblCarModel will bind to the DataContext s Model property as specified in the binding expression s Path property Each of these bindings is using a OneWay mode, which means the label content will be bound only once, regardless if the underlying object property being bound to changes The Path component of the XAML Binding expression simply tells the XAML processor to take its value from a specific property of its DataContext The Path value can also express properties that are nested, such as in the case of nested complex objects In these cases, you use dot notation to reach the desired property, such as Property SomeObjectSomeOtherProperty

You can see that the labels now display the Make and Model of the Car object that was assigned to the DataContext of the window (See Figure 3-1)

Defining a binding with C#

Defining bindings can also be done using C# To demonstrate this, remove the Content attribute entirely from both labels in the XAML file The label markup should now resemble the following:

<Label x:Name= lblCarMake GridRow= 0 GridColumn= 0 /> <Label x:Name= lblCarModel GridRow= 0 GridColumn= 1 />

Modify the GenerateData() method in MainWindowxamlcs to implement the Binding definitions in code To do this, you must instantiate Binding objects directly The constructor of the Binding object takes in the string Path value Use the BindingOperations class to apply the Binding to the Content dependency property of your labels

BindingOperations is a helper class provided to you by WPF It has static methods that give you the power to add and clear data binding definitions on application elements The following code shows you how to define the Binding objects, and assign the binding to the Content of the labels:

private void GenerateData() { Car car1 = new Car() { Make = Athlon , Model = XYZ }; Binding makeBinding = new Binding( Make ); makeBindingMode = BindingModeOneTime; BindingOperationsSetBinding(lblCarMake, LabelContentProperty, makeBinding); Binding modelBinding = new Binding( Model ); modelBindingMode = BindingModeOneTime; BindingOperationsSetBinding(lblCarModel, LabelContentProperty, modelBinding); thisDataContext = car1; }

Run the application and observe that it runs the same way as when the bindings were defined using XAML Dependency properties are typically defined with the suffix Property, but you only see them this way navigating MSDN documentation and accessing them through code In XAML, you specify dependency property attributes by dropping the Property suffix on the name