C# 在代码隐藏中访问silverlight用户控件的公共属性

我创建了一个简单的Silverlight用户控件，并定义了一个公共属性

AllowMultiple

public bool AllowMultiple{get；set；}

现在，我在XAML中设置此公共属性，如下所示：

<Controls1:PeopleChooser Name="SinglePeopleChooser" AllowMultiple="False" Width="Auto" d:LayoutOverrides="Height"/>
<Controls1:PeopleChooser Name="MultiplePeopleChooser" AllowMultiple="True" Width="Auto" d:LayoutOverrides="Height"/>

---

可能是因为在构造函数初始化期间，框架没有将此公共属性的值分配给对象。

使用backfield转换公共属性

    private bool _allowMultiple;
    public bool AllowMultiple
    {
        get { return _allowMultiple; }
        set { _allowMultiple = value; }
    }

---

在setter中放置一个断点并检查它是否命中构造函数，如果没有，您可以使用

Loaded

事件检查并利用该断点

我能够通过加载的事件解决它。不需要依赖属性。请参阅下面的代码。我可以在

Loaded

事件中成功访问属性值

 public PeopleChooser()
        {

            this.Loaded += PeopleChooser_Loaded;
            InitializeComponent();                     

        }


  void PeopleChooser_Loaded(object sender, RoutedEventArgs e)
        {
            if (AllowMultiple)
            {
                UsersListBox.Visibility = System.Windows.Visibility.Visible;
                UserTextBox.Visibility = System.Windows.Visibility.Collapsed;
                ResolveButton.Visibility = Visibility.Collapsed;            

            }
            else
            {
                UsersListBox.Visibility = System.Windows.Visibility.Collapsed;
                UserTextBox.Visibility = System.Windows.Visibility.Visible;
                ResolveButton.Visibility = Visibility.Visible;
            }

---

如果使用依赖项属性，则可以将其他元素属性绑定到人员选择器的AllowMultiple属性，并使用可见性转换器显示/隐藏它们。例如：

public partial class PeopleChooser : UserControl
{
    public PeopleChooser()
    {
        InitializeComponent();
    }

    public static readonly DependencyProperty AllowMultipleProperty = DependencyProperty.Register("AllowMultiple", typeof(bool), typeof(PeopleChooser), null);
    public bool AllowMultiple
    {
        get { return (bool)GetValue(AllowMultipleProperty); }
        set { SetValue(AllowMultipleProperty, value); }
    }
}

<UserControl x:Class="TestSilverlightApplication.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400"
    xmlns:lcl="clr-namespace:TestSilverlightApplication">
    <UserControl.Resources>
        <lcl:VisibilityConverter x:Key="VisibilityConverter" />
    </UserControl.Resources>
    <Grid x:Name="LayoutRoot" Background="White">
        <StackPanel Orientation="Vertical">
            <Button Click="Button_Click" Content="Toggle allow multiple" />
            <lcl:PeopleChooser x:Name="lclPeopleChooser" AllowMultiple="False"></lcl:PeopleChooser>
            <TextBlock Text="Dependent content" Visibility="{Binding AllowMultiple, ElementName=lclPeopleChooser, Converter={StaticResource VisibilityConverter}}" />
        </StackPanel>

    </Grid>
</UserControl>

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        lclPeopleChooser.AllowMultiple = !lclPeopleChooser.AllowMultiple;
    }

public class VisibilityConverter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        bool parsedValue = false;
        bool.TryParse(value.ToString(), out parsedValue);
        if (parsedValue)
        {
            return Visibility.Visible;
        }
        return Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

公共部分类PeopleChooser:UserControl
{
公共人物选择器（）
{
初始化组件（）；
}
公共静态只读DependencyProperty AllowMultipleProperty=DependencyProperty.Register（“AllowMultiple”、typeof（bool）、typeof（PeopleChooser）、null）；
公共布尔允许多个
{
获取{return（bool）GetValue（AllowMultipleProperty）；}
set{SetValue（AllowMultipleProperty，value）；}
}
}
私有无效按钮\u单击（对象发送者，路由目标e）
{
lclpeopechooser.AllowMultiple=！lclpeopechooser.AllowMultiple；
}
公共类可视性转换器：IValueConverter
{
公共对象转换（对象值、类型targetType、对象参数、System.Globalization.CultureInfo区域性）
{
bool parsedValue=false；
bool.TryParse（value.ToString（），out-parsedValue）；
if（parsedValue）
{
返回可见性。可见；
}
返回可见性。折叠；
}
公共对象转换回（对象值、类型targetType、对象参数、System.Globalization.CultureInfo区域性）
{
抛出新的NotImplementedException（）；
}
}

---

通过这种方式，您可以避免页面事件，并可能将AllowMultiple属性绑定到视图模型属性，并让UI自行处理。

我认为它必须是依赖性属性。@TrueBlueAusie:是的，这没有什么不同，但目的是检查值何时设置。这样他就可以得到相应的值。此外，设置直接值不必是依赖项属性。对于绑定，它需要是依赖项属性。@TrueBlueAussie:您的注释权限中已经给出了解释。。谢谢你的否决票，并作了详细的解释……我在回答中已经提到了。。。是的，它实际上不需要dp。+1：为先前对DPs的混淆道歉。我正要发布同样的答案，但你自己发现了。

public partial class PeopleChooser : UserControl
{
    public PeopleChooser()
    {
        InitializeComponent();
    }

    public static readonly DependencyProperty AllowMultipleProperty = DependencyProperty.Register("AllowMultiple", typeof(bool), typeof(PeopleChooser), null);
    public bool AllowMultiple
    {
        get { return (bool)GetValue(AllowMultipleProperty); }
        set { SetValue(AllowMultipleProperty, value); }
    }
}

<UserControl x:Class="TestSilverlightApplication.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400"
    xmlns:lcl="clr-namespace:TestSilverlightApplication">
    <UserControl.Resources>
        <lcl:VisibilityConverter x:Key="VisibilityConverter" />
    </UserControl.Resources>
    <Grid x:Name="LayoutRoot" Background="White">
        <StackPanel Orientation="Vertical">
            <Button Click="Button_Click" Content="Toggle allow multiple" />
            <lcl:PeopleChooser x:Name="lclPeopleChooser" AllowMultiple="False"></lcl:PeopleChooser>
            <TextBlock Text="Dependent content" Visibility="{Binding AllowMultiple, ElementName=lclPeopleChooser, Converter={StaticResource VisibilityConverter}}" />
        </StackPanel>

    </Grid>
</UserControl>

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        lclPeopleChooser.AllowMultiple = !lclPeopleChooser.AllowMultiple;
    }

public class VisibilityConverter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        bool parsedValue = false;
        bool.TryParse(value.ToString(), out parsedValue);
        if (parsedValue)
        {
            return Visibility.Visible;
        }
        return Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}