「UpdateSourceTrigger = PropertyChanged」相當於Windows Phone 7 TextBox

Question

有沒有辦法讓Windows Phone 7中的TextBox更新綁定，因爲用戶鍵入每個字母而不是失去焦點後？

像下面的文本框WPF會做：

<TextBox Text="{Binding Path=TextProperty, UpdateSourceTrigger=PropertyChanged}"/> 

Answer 1

Silverlight for WP7不支持您列出的語法。代替運行以下：

<TextBox TextChanged="OnTextBoxTextChanged" 
     Text="{Binding MyText, Mode=TwoWay, 
       UpdateSourceTrigger=Explicit}" /> 

UpdateSourceTrigger = Explicit這裏是一個聰明的獎金。 這是什麼？Explicit：僅在調用UpdateSource方法時更新綁定源。當用戶離開TextBox時，它可以爲您節省一個額外的綁定設置。

在C＃：

private void OnTextBoxTextChanged(object sender, TextChangedEventArgs e) 
{ 
    TextBox textBox = sender as TextBox; 
    // Update the binding source 
    BindingExpression bindingExpr = textBox.GetBindingExpression(TextBox.TextProperty); 
    bindingExpr.UpdateSource(); 
} 

Answer 2

不通過綁定語法，沒有，但它是不很容易。您必須處理TextChanged事件並在綁定上調用UpdateSource。

private void TextBox_TextChanged(object sender, TextChangedEventArgs e) 
{ 
    ((TextBox) sender).GetBindingExpression(TextBox.TextProperty).UpdateSource(); 
} 

這可以很容易地轉換成attached behavior。

Answer 3

在TextChanged事件調用UpdateSource()。

BindingExpression be = itemNameTextBox.GetBindingExpression(TextBox.TextProperty); 
be.UpdateSource(); 

Answer 4

我喜歡使用附加屬性。以防萬一你進入那些小雜事。

<toolkit:DataField Label="Name"> 
    <TextBox Text="{Binding Product.Name, Mode=TwoWay}" c:BindingUtility.UpdateSourceOnChange="True"/> 
</toolkit:DataField> 

然後支持代碼。

public class BindingUtility 
{ 
public static bool GetUpdateSourceOnChange(DependencyObject d) 
{ 
    return (bool)d.GetValue(UpdateSourceOnChangeProperty); 
} 

public static void SetUpdateSourceOnChange(DependencyObject d, bool value) 
{ 
    d.SetValue(UpdateSourceOnChangeProperty, value); 
} 

// Using a DependencyProperty as the backing store for … 
public static readonly DependencyProperty 
    UpdateSourceOnChangeProperty = 
    DependencyProperty.RegisterAttached(
    "UpdateSourceOnChange", 
    typeof(bool), 
       typeof(BindingUtility), 
    new PropertyMetadata(false, OnPropertyChanged)); 

private static void OnPropertyChanged (DependencyObject d, 
    DependencyPropertyChangedEventArgs e) 
{ 
    var textBox = d as TextBox; 
    if (textBox == null) 
    return; 
    if ((bool)e.NewValue) 
    { 
    textBox.TextChanged += OnTextChanged; 
    } 
    else 
    { 
    textBox.TextChanged -= OnTextChanged; 
    } 
} 
static void OnTextChanged(object s, TextChangedEventArgs e) 
{ 
    var textBox = s as TextBox; 
    if (textBox == null) 
    return; 

    var bindingExpression = textBox.GetBindingExpression(TextBox.TextProperty); 
    if (bindingExpression != null) 
    { 
    bindingExpression.UpdateSource(); 
    } 
} 
} 

Answer 5

UpdateSourceTrigger =我明確不工作，因此進出口使用自TextBox

public class TextBoxEx : TextBox 
{ 
    public TextBoxEx() 
    { 
     TextChanged += (sender, args) => 
          { 
           var bindingExpression = GetBindingExpression(TextProperty); 
           if (bindingExpression != null) 
           { 
            bindingExpression.UpdateSource(); 
           } 
          }; 
    } 

} 

Answer 6

衍生化自定義類它的代碼只是一條線！

(sender as TextBox).GetBindingExpression(TextBox.TextProperty).UpdateSource(); 

您可以在頁面的後臺代碼創建一個通用的TextChanged事件（例如「ImmediateTextBox_TextChanged」），並且比它在頁面鏈接到任何文本框。

Answer 7

您可以編寫自己的文本框的行爲來處理框TextChanged更新：

這是我的樣品PasswordBox，但你可以簡單的改變它來處理任何對象的任何屬性。

public class UpdateSourceOnPasswordChangedBehavior 
    : Behavior<PasswordBox> 
{ 
    protected override void OnAttached() 
    { 
     base.OnAttached(); 
     AssociatedObject.PasswordChanged += OnPasswordChanged; 
    } 

    protected override void OnDetaching() 
    { 
     base.OnDetaching(); 
     AssociatedObject.PasswordChanged -= OnPasswordChanged; 
    } 

    private void OnPasswordChanged(object sender, RoutedEventArgs e) 
    { 
     AssociatedObject.GetBindingExpression(PasswordBox.PasswordProperty).UpdateSource(); 
    } 
} 

Ussage：

<PasswordBox x:Name="Password" Password="{Binding Password, Mode=TwoWay}" > 
    <i:Interaction.Behaviors> 
     <common:UpdateSourceOnPasswordChangedBehavior/> 
    </i:Interaction.Behaviors> 
</PasswordBox> 

Answer 8

我把Praetorian's answer並提出繼承TextBox所以你不必這種行爲背後矇混過關了您的視圖代碼的擴展類。

C-夏普：

public class TextBoxUpdate : TextBox 
{ 
    public TextBoxUpdate() 
    { 
     TextChanged += OnTextBoxTextChanged; 
    } 
    private void OnTextBoxTextChanged(object sender, TextChangedEventArgs e) 
    { 
     TextBox senderText = (TextBox)sender; 
     BindingExpression bindingExp = senderText.GetBindingExpression(TextBox.TextProperty); 
     bindingExp.UpdateSource(); 
    } 
} 

的VisualBasic：

Public Class TextBoxUpdate : Inherits TextBox 

    Private Sub OnTextBoxTextChanged(sender As Object, e As TextChangedEventArgs) Handles Me.TextChanged 
     Dim senderText As TextBox = DirectCast(sender, TextBox) 
     Dim bindingExp As BindingExpression = senderText.GetBindingExpression(TextBox.TextProperty) 
     bindingExp.UpdateSource() 
    End Sub 

End Class 

然後在XAML這樣調用：

<local:TextBoxUpdate Text="{Binding PersonName, Mode=TwoWay}"/>