绑定到带验证的双字段 [英] Binding to double field with validation

问题描述

我正在尝试使用 UpdateSourceTrigger=PropertyChanged 将 TextBox 绑定到某个对象的 double 属性.目标是在编辑期间立即验证输入的值是否在允许范围内(如果不是，则显示错误).我想在模型级别实现验证，即通过 IDataErrorInfo.

I'm trying to bind TextBox to double property of some object with UpdateSourceTrigger=PropertyChanged. The goal is to immediately during editing validate entered value to be in allowed range (and display an error if not). I want to implement validation on Model level, i.e. via IDataErrorInfo.

当我绑定到 int 属性时，一切都很好，但是如果属性是双精度，则会出现令人沮丧的编辑行为:擦除数字小数部分的最后一个有效数字后 - 小数点分隔符会自动擦除(所有可能的小数点为零).例如，从数字12.03"中删除数字3"后，文本将更改为12"而不是12.0".

All works great when I bind to int property, but if property is double then a frustrating editing behavior appears: after erasing last significant digit in fractional part of number - the decimal separator is automatically erased (with all possible fractional zeroes). For example, after erasing digit '3' from number '12.03' the text is changed to '12' instead of '12.0'.

请帮忙.

这是示例代码:

MainWindow.xaml:

MainWindow.xaml:

<Window x:Class="BindWithValidation.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="80" Width="200" WindowStartupLocation="CenterOwner">

  <StackPanel>
    <TextBox Width="100" Margin="10" Text="{Binding DoubleField, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=True}">
      <TextBox.Style>
        <Style TargetType="TextBox">
          <Style.Triggers>
            <Trigger Property="Validation.HasError" Value="true">
              <Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}"/>
            </Trigger>
          </Style.Triggers>
        </Style>
      </TextBox.Style>
    </TextBox>
  </StackPanel>
</Window>

MainWindow.xaml.cs:

MainWindow.xaml.cs:

namespace BindWithValidation
{
  public partial class MainWindow : Window
  {
    private UISimpleData _uiData = new UISimpleData();

    public MainWindow()
    {
      InitializeComponent();
      DataContext = _uiData;
    }
  }
}

UISimpleData.cs:

UISimpleData.cs:

namespace BindWithValidation
{
  public class UISimpleData : INotifyPropertyChanged, IDataErrorInfo
  {
    private double _doubleField = 12.03;

    public double DoubleField
    {
      get
      {
        return _doubleField;
      }
      set
      {
        if (_doubleField == value)
          return;

        _doubleField = value;
        RaisePropertyChanged("DoubleField");
      }
    }

    public string this[string propertyName]
    {
      get
      {
        string validationResult = null;
        switch (propertyName)
        {
          case "DoubleField":
          {
            if (DoubleField < 2 || DoubleField > 5)
              validationResult = "DoubleField is out of range";
            break;
          }

          default:
            throw new ApplicationException("Unknown Property being validated on UIData");
        }

        return validationResult;
      }
    }

    public string Error { get { return "not implemented"; } }

    public event PropertyChangedEventHandler PropertyChanged;

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

推荐答案

将浮点值绑定到文本框的行为已更改从 .NET 4 到 4.5..NET 4.5 不再可能输入带有UpdateSourceTrigger ="的分隔符(逗号或点)PropertyChanged' 默认情况下.

The behavior of binding float values to a textbox has been changed from .NET 4 to 4.5. With .NET 4.5 it is no longer possible to enter a separator character (comma or dot) with ‘UpdateSourceTrigger = PropertyChanged’ by default.

微软表示，这是(有意)

如果你仍然想使用‘UpdateSourceTrigger = PropertyChanged’，你可以通过添加来强制 .NET 4.5 应用程序中的 .NET 4 行为将以下代码行添加到 App.xaml.cs 的构造函数中:

If you still want to use ‘UpdateSourceTrigger = PropertyChanged’, you can force the .NET 4 behavior in your .NET 4.5 application by adding the following line of code to the constructor of your App.xaml.cs:

public App()  
{
    System.Windows.FrameworkCompatibilityPreferences
               .KeepTextBoxDisplaySynchronizedWithTextProperty = false;   
}

(Sebastian Lux - 从 此处)

(Sebastian Lux - Copied verbatim from here)

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