c# - 与字符串数据类型属性绑定的 WPF 文本框应仅接受数值

Question

我有一个文本框，其文本与字符串数据类型属性绑定。但我只需要在此文本框中输入数值。

它看起来很奇怪，但这是要求之一，同一个文本框可以接受字符串和数值。我不能拿两个文本框来处理这个文本框的可见性。

Answer 1

你可以这样做

<TextBox Text="{Binding Path=Amount}">            
    <i:Interaction.Behaviors>                
        <Behaviors:TextBoxInputBehavior InputMode="DigitInput" />
    </i:Interaction.Behaviors>
</TextBox>

这些天我在这里发布代码：Validate decimal numbers in a WPF TextBox

Answer 2

您可以使用以下方法很好地做到这一点AttachedProperty：

我有一个TextBoxProperties 用我附加的TextBox控件属性调用的类：

#region IsNumericOnly

/// <summary>
/// Provides the ability to restrict the text input of the TextBox control to only allow numeric values to be entered.
/// </summary>
public static readonly DependencyProperty IsNumericOnlyProperty = DependencyProperty.RegisterAttached("IsNumericOnly", typeof(bool), typeof(TextBoxProperties), new UIPropertyMetadata(default(bool), OnIsNumericOnlyChanged));

/// <summary>
/// Gets the value of the IsNumericOnly property.
/// </summary>
/// <param name="dependencyObject">The DependencyObject to return the IsNumericOnly property value from.</param>
/// <returns>The value of the IsNumericOnly property.</returns>
public static bool GetIsNumericOnly(DependencyObject dependencyObject)
{
    return (bool)dependencyObject.GetValue(IsNumericOnlyProperty);
}

/// <summary>
/// Sets the value of the IsNumericOnly property.
/// </summary>
/// <param name="dependencyObject">The DependencyObject to set the IsNumericOnly property value of.</param>
/// <param name="value">The value to be assigned to the IsNumericOnly property.</param>
public static void SetIsNumericOnly(DependencyObject dependencyObject, bool value)
{
    dependencyObject.SetValue(IsNumericOnlyProperty, value);
}

/// <summary>
/// Adds key listening event handlers to the TextBox object to prevent non numeric key strokes from being accepted if the IsNumericOnly property value is true, or removes them otherwise.
/// </summary>
/// <param name="dependencyObject">The TextBox object.</param>
/// <param name="dependencyPropertyChangedEventArgs">The DependencyPropertyChangedEventArgs object containing event specific information.</param>
public static void OnIsNumericOnlyChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
    TextBox textBox = dependencyObject as TextBox;
    if (textBox != null)
    {
        bool newIsNumericOnlyValue = (bool)dependencyPropertyChangedEventArgs.NewValue;
        TextCompositionEventHandler textBox_PreviewTextInput = new TextCompositionEventHandler((s, e) => e.Handled = !e.Text.All(c => Char.IsNumber(c) && c != ' '));
        KeyEventHandler textBox_PreviewKeyDown = new KeyEventHandler((s, e) => e.Handled = e.Key == Key.Space);
        if (newIsNumericOnlyValue)
        {
            textBox.PreviewTextInput += textBox_PreviewTextInput;
            textBox.PreviewKeyDown += textBox_PreviewKeyDown;
        }
        else
        {
            textBox.PreviewTextInput -= textBox_PreviewTextInput;
            textBox.PreviewKeyDown -= textBox_PreviewKeyDown;
        }
    }
}

#endregion

它是这样使用的：

添加 XML 命名空间：

xmlns:Attached="clr-namespace:Fully.Qualified.Namespace"

然后是 XAML：

<TextBox Text="{Binding YourString}" Attached:TextBoxProperties.IsNumericOnly="True" />

您可以将此应用于任何Textbox数字，并且不允许输入任何非数字数字。

Answer 3

如果您只需要数值，请执行以下操作。

1. 如果所有字符都是数字，则在您的属性设置器中验证新值。
2. 如果是，则设置新值
3. 如果不是这样，请不要做任何事情。

绑定使用 getter 和 setter。一旦绑定更新了属性的 setter，它就会调用它的 getter。当您在 TextBox 和 setter 中输入文本时，您不会设置值。文本不会被输入。

替代方法是使用 ValidationRules。