[英]The value of DependencyProperty is not propagated from XAML to code behind
The problem is that DependencyProperty is not getting assigned to the value specified in XAML: 问题是DependencyProperty没有分配给XAML中指定的值:
I have two different user controls let's say UserControl1 and UserControl2 that define another user control which is common to both controls: 我有两个不同的用户控件,比如说UserControl1和UserControl2,它们定义了两个控件共有的另一个用户控件:
UserControl1.xaml: UserControl1.xaml:
<modulename:MyUserControl ....somecode... DataOrientation="Horizontal">
</modulename:MyUserControl>
UserControl2.xaml UserControl2.xaml
<modulename:MyUserControl ....somecode... DataOrientation="Vertical">
</modulename:MyUserControl>
The difference between both UserControls is that UserControl1 has to display the data using Horizontal orientation and UserControl2 has to display the data using Vertical Orientation. 两种UserControl的区别在于,UserControl1必须使用“水平方向”显示数据,而UserControl2必须使用“垂直方向”显示数据。
Inside of the MyUserControl's code behind I defined a Dependency Property as follows: 在MyUserControl的代码内部,我定义了一个Dependency属性,如下所示:
public static readonly DependencyProperty DataOrientationProperty =
DependencyProperty.Register ("DataOrientation",typeof(String),typeof(MyUserControl));
public String DataOrientation
{
get {return (String)GetValue(DataOrientationProperty);}
set { SetValue(DataOrientationProperty, value); }
}
These are fragment of the code inside of MyUserControl.xaml: 这些是MyUserControl.xaml中的代码片段:
...
<StockPanel>
<Grid Name="MyGrid" SizeChanged="MyGrid_SizeChanged">
<Grid.ColumnDefinitions>
<ColumnDefinitions Width="*"/>
<ColumnDefinitions Width="100"/>
</Grid.ColumnDefinitions>
<ScrollViewer Name="MySV" Grid.Column="0" ....>
<Grid Name="DetailGrid"/>
</ScrollViewer>
<Grid Grid.Column="1" .........>
......Some Option Data....
</Grid>
</Grid>
</StockPanel>
The idea is to change ColumnDefinitions to RowDefinitions and Grid.Column to Grid.Rows depending on the orientation flag: 想法是根据方向标记将ColumnDefinitions更改为RowDefinitions,将Grid.Column更改为Grid.Rows:
If the flag is "Horizontal", UserControl displays "DetailsGrid" and "Option Data" Grid side by side, meaning "DetailGrid" is in Column 0 and "Option Data" Grid in Column 1. 如果标记为“ Horizontal”,则UserControl并排显示“ DetailsGrid”和“ Option Data”网格,这意味着“ DetailGrid”在第0列中,而“ Option Data”网格在第1列中。
If the flag is "Vertical" UserControl displays "DetailGrid" in Row 1 and "Option Data" in Row 0. 如果标记为“ Vertical”,则UserControl在第1行中显示“ DetailGrid”,在第0行中显示“ Option Data”。
Need some help on that issue. 在这个问题上需要一些帮助。
Thank you in advance. 先感谢您。
Two things, make the dependency property have a changed handler and verify in the debugger that the value is actually making it to the user control. 两件事情,使dependency属性的处理程序发生更改,并在调试器中验证该值实际上已在用户控件中使用。 Also setup a default value for the user control (the below uses "Horizontal") but you decide how to handle that.
还要为用户控件设置一个默认值(以下使用“水平”),但是您可以决定如何处理它。
public string DataOrientation
{
get { return (string)GetValue(DataOrientationProperty); }
set { SetValue(DataOrientationProperty, value); }
}
/// <summary>
/// Identifies the DataOrientation dependency property.
/// </summary>
public static readonly DependencyProperty DataOrientationProperty =
DependencyProperty.Register(
"DataOrientation",
typeof(string),
typeof(MyClass),
new PropertyMetadata("Horizontal", // Default to Horizontal; Can use string.Empty
OnDataOrientationPropertyChanged));
/// <summary>
/// DataOrientationProperty property changed handler.
/// </summary>
/// <param name="d">MyClass that changed its DataOrientation.</param>
/// <param name="e">Event arguments.</param>
private static void OnDataOrientationPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
MyClass source = d as MyClass; // Put breakpoint here.
string value = (string)e.NewValue;
}
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