如何将silverlight usercontrol属性传播给父级？

Question

我希望自定义用户控件中的某些属性可供父页面使用。我创建了一个小样本来说明我在寻找什么。

我正在尝试使用MVVM模式和所有绑定机制来实现它。

USERCONTROL XAML

<UserControl x:Class="TestCustomUserControl.MyControls.UserNameControl"
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"
xmlns:local="clr-namespace:TestCustomUserControl.ViewModels"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">
<UserControl.Resources>
    <local:UserNameViewModel x:Key="TheViewModel"/>
</UserControl.Resources>
<Grid x:Name="NameCtrlRoot" Background="White" DataContext="{StaticResource TheViewModel}">
    <StackPanel>
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto" />
                <ColumnDefinition />
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition />
                <RowDefinition />
                <RowDefinition />
                <RowDefinition />
                <RowDefinition />
            </Grid.RowDefinitions>
            <TextBlock Grid.Row="0" Grid.Column="0" Text="First Name:" />
            <TextBlock Grid.Row="1" Grid.Column="0" Text="Last Name: "/>
            <TextBox Grid.Row="0" Grid.Column="1" x:Name="txtFirstName" Text="{Binding FirstName, Mode=TwoWay}">
                <i:Interaction.Behaviors>
                    <!-- This behavior updates the binding after a specified delay
                                instead of the user having to lose focus on the TextBox. -->
                    <local:TextChangedDelayedBindingBehavior RefreshTimeMilliseconds="750" />
                </i:Interaction.Behaviors>
            </TextBox>
            <TextBox Grid.Row="1" Grid.Column="1" x:Name="txtLastName" Text="{Binding LastName, Mode=TwoWay}">
                <i:Interaction.Behaviors>
                    <!-- This behavior updates the binding after a specified delay
                                instead of the user having to lose focus on the TextBox. -->
                    <local:TextChangedDelayedBindingBehavior RefreshTimeMilliseconds="750" />
                </i:Interaction.Behaviors>
            </TextBox>
            <TextBlock Grid.Row="3" Grid.Column="0" Text="fullname inside control:" />
            <TextBlock Grid.Row="3" Grid.Column="1" Text="{Binding FullName}" />
            <Border Height="1" Background="Black" Grid.Column="2" Grid.Row="4" />
        </Grid>
    </StackPanel>
</Grid>

以上Usercontrol绑定到以下VIEWMODEL

public class BaseViewModel : INotifyPropertyChanged
{

    public event PropertyChangedEventHandler PropertyChanged;


    protected void NotifyPropertyChanged(string propName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propName));
    }
}

public class UserNameViewModel : BaseViewModel
{
    private String _firstName;
    public String FirstName
    {
        get { return _firstName; }
        set
        {
            _firstName = value;
            NotifyPropertyChanged("FirstName");
            OnNameChange();
        }
    }

    private String _lastName;
    public String LastName
    {
        get { return _lastName; }
        set
        {
            _lastName = value;
            NotifyPropertyChanged("LastName");
            OnNameChange();
        }
    }

    private void OnNameChange()
    {
        FullName = String.Format("{0} {1}", FirstName, LastName);
    }

    public String _fullName;
    public String FullName
    {
        get { return _fullName; }
        set { 
            _fullName = value;
            NotifyPropertyChanged("FullName");
        }
    }
}

使用上述USERCONTROL的消费者页面

<navigation:Page xmlns:my="clr-namespace:TestCustomUserControl.MyControls"  x:Class="TestCustomUserControl.Views.ConsumeName" 
       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"
       xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
       d:DesignWidth="640" d:DesignHeight="480"
       Title="ConsumeName Page">
<Grid x:Name="LayoutRoot">
    <StackPanel>
        <my:UserNameControl x:Name="MyNameControl"/>
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="10" />
                <RowDefinition />
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition />
            </Grid.ColumnDefinitions>
            <TextBlock Grid.Row="1" Grid.Column="0" Text="Full Name in Parent: " />
            <TextBlock Grid.Row="1" Grid.Column="1" Text="{Binding FullName, ElementName=MyNameControl}"/>
        </Grid>
    </StackPanel>
</Grid>

现在我的问题是，如果您查看与用户控件关联的视图模型，它有一个名为FullName的属性，我希望通过Usercontrol公开它，以便我可以从使用页面访问它。它像消费页面想要访问usercontrol的一些属性。我不太确定如何实现这一目标。我想坚持使用MVVM模式。

Answer 1

您已经对一个StaticResource进行了十分转换，因此您可以在两个视图中使用它。 这样做

<UserControl.Resources>
    <local:UserNameViewModel x:Key="TheViewModel"/>
</UserControl.Resources>

名称页面中的

。如果只是将DataContext添加到Grid

<Grid x:Name="LayoutRoot" DataContext="{StaticResource TheViewModel}">

这应该有效。 （您不再需要ElementName = MyNameControl。）

my：UserNameControl应该继承DataContext。如果没有，你必须在这里添加。

<my:UserNameControl DataContext="{StaticResource TheViewModel}"/>

这应该有用。

现在本地：具有键TheViewModel的UserNameViewModel只能在您定义它的地方实现。如果您在app.xaml中定义它，则可以从应用程序的任何位置访问它。

希望这一切。

BR，

TJ

Answer 2

我正在回答我自己的问题。但在回答我的问题之前，只想澄清一些事情。我试图用自己的ViewModel创建一个完全封装的UserControl。在使用usercontrol的地方，消费者应该对usercontrol的内部视图模型一无所知。只有我希望消费者拥有的通信选项是通过设置一些属性和使用绑定机制。 所以我解决问题的方法是，我在UserControl中创建依赖属性，并在usercontrol的viewmodel中发生更改时设置它。

UserNameControl.xaml（usercontrol）

<UserControl x:Class="TestCustomUserControl.MyControls.UserNameControl"
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"
xmlns:local="clr-namespace:TestCustomUserControl.ViewModels"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">
<UserControl.Resources>
    <local:UserNameViewModel x:Key="TheViewModel"/>
</UserControl.Resources>
<Grid x:Name="NameCtrlRoot" Background="White" DataContext="{StaticResource TheViewModel}">
    <StackPanel>
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto" />
                <ColumnDefinition />
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition />
                <RowDefinition />
                <RowDefinition />
                <RowDefinition />
                <RowDefinition />
            </Grid.RowDefinitions>
            <TextBlock Grid.Row="0" Grid.Column="0" Text="First Name:" />
            <TextBlock Grid.Row="1" Grid.Column="0" Text="Last Name: "/>
            <TextBox Grid.Row="0" Grid.Column="1" x:Name="txtFirstName" Text="{Binding FirstName, Mode=TwoWay}">
                <i:Interaction.Behaviors>
                    <!-- This behavior updates the binding after a specified delay
                                instead of the user having to lose focus on the TextBox. -->
                    <local:TextChangedDelayedBindingBehavior RefreshTimeMilliseconds="750" />
                </i:Interaction.Behaviors>
            </TextBox>
            <TextBox Grid.Row="1" Grid.Column="1" x:Name="txtLastName" Text="{Binding LastName, Mode=TwoWay}">
                <i:Interaction.Behaviors>
                    <!-- This behavior updates the binding after a specified delay
                                instead of the user having to lose focus on the TextBox. -->
                    <local:TextChangedDelayedBindingBehavior RefreshTimeMilliseconds="750" />
                </i:Interaction.Behaviors>
            </TextBox>
            <TextBlock Grid.Row="3" Grid.Column="0" Text="fullname inside control:" />
            <TextBlock Grid.Row="3" Grid.Column="1" Text="{Binding FullName}" />
            <Border Height="1" Background="Black" Grid.Column="2" Grid.Row="4" />
        </Grid>
    </StackPanel>
</Grid>

BaseViewModel.cs

public class BaseViewModel : INotifyPropertyChanged
{
    #region Implementation of INotifyPropertyChanged

    public event PropertyChangedEventHandler PropertyChanged;

    #endregion

    protected void NotifyPropertyChanged(string propName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propName));
    }
}

UserNameViewModel.cs

 public class UserNameViewModel : BaseViewModel
{
    private String _firstName;
    public String FirstName
    {
        get { return _firstName; }
        set
        {
            _firstName = value;
            NotifyPropertyChanged("FirstName");
            OnNameChange();
        }
    }

    private String _lastName;
    public String LastName
    {
        get { return _lastName; }
        set
        {
            _lastName = value;
            NotifyPropertyChanged("LastName");
            OnNameChange();
        }
    }

    public Action NameChanged { get; set; }
    private void OnNameChange()
    {
        FullName = String.Format("{0} {1}", FirstName, LastName);
        if(NameChanged != null) NameChanged.Invoke();
    }

    private String _fullName;
    public String FullName
    {
        get { return _fullName; }
        set { 
            _fullName = value;
            NotifyPropertyChanged("FullName");
        }
    }
}

UserNameControl.xaml.cs（DependencyProperty声明后面的Usercontrol代码）

public partial class UserNameControl : UserControl
{
    private UserNameViewModel _TheViewModel;
    public UserNameControl()
    {
        InitializeComponent();
        _TheViewModel = Resources["TheViewModel"] as UserNameViewModel;
        _TheViewModel.NameChanged = OnNameChanged;
    }

    public String SelectedFullName
    {
        get { return (String) GetValue(SelectedFullNameProperty); }
        set { SetValue(SelectedFullNameProperty, value); }
    }
    public static readonly DependencyProperty SelectedFullNameProperty =
        DependencyProperty.Register("SelectedFullName", typeof (String), typeof (UserNameControl), null);

    private void OnNameChanged()
    {
        SelectedFullName = _TheViewModel.FullName;
    }
}

ConsumeName.xaml（消费者导航页面，usercontrol上方的用户并将SelectedFullName拉入UserFullName）

<navigation:Page xmlns:my="clr-namespace:TestCustomUserControl.MyControls"  x:Class="TestCustomUserControl.Views.ConsumeName" 
       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"
       xmlns:local="clr-namespace:TestCustomUserControl.ViewModels"
       xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
       d:DesignWidth="640" d:DesignHeight="480"
       Title="ConsumeName Page">
<navigation:Page.Resources>
    <local:ConsumeNameViewModel x:Key="TheConsumeNameViewModel"/>
</navigation:Page.Resources>
<Grid x:Name="LayoutRoot" DataContext="{StaticResource TheConsumeNameViewModel}">
    <StackPanel>
        <my:UserNameControl x:Name="MyNameControl" SelectedFullName="{Binding UserFullName, Mode=TwoWay}" />
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition Height="10" />
                <RowDefinition />
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition />
            </Grid.ColumnDefinitions>
            <TextBlock Grid.Row="1" Grid.Column="0" Text="Full Name in Parent: " />
            <TextBlock Grid.Row="1" Grid.Column="1" Text="{Binding UserFullName}"/>
        </Grid>
    </StackPanel>
</Grid>

ConsumeNameViewModel.cs

public class ConsumeNameViewModel : BaseViewModel
{

    private string _UserFullName;

    public string UserFullName
    {
        get { return _UserFullName; }
        set
        {
            if (value != _UserFullName)
            {
                _UserFullName = value;
                NotifyPropertyChanged("UserFullName");
            }
        }
    }

}