WPF驗證未綁定的文本框

Question

是否可以在沒有綁定部分的情況下使用驗證？事情是我的文本框沒有綁定到任何對象，但我仍然想驗證它的內容。我到目前爲止發現的唯一方法是這樣的：

<TextBox Grid.Row="0" Grid.Column="1" MaxLength="50" x:Name="textBoxTubeName" Margin="5,5,0,5"> 
     <TextBox.Text> 
      <Binding Path="Name" UpdateSourceTrigger="PropertyChanged" Mode="TwoWay" NotifyOnValidationError="True"> 
       <Binding.ValidationRules> 
        <validation:InvalidCharactersRule /> 
       </Binding.ValidationRules> 
      </Binding> 
     </TextBox.Text> 
    </TextBox> 

但同樣，當TextBox.Text必然的東西（在這種情況下，名稱屬性），它只能，我怎麼會去這沒有約束力？

謝謝！

Answer 1

According to the MSDN forums這是不可能的，但它是計劃（注：這是一箇舊的帖子）。但是，我仍然找不到一種方法來實現它，因此可能尚未實現。

Answer 2

這是一個很大棘手的代碼隱藏的事。基本上，你可以設置代碼的臨時綁定，並提出驗證錯誤，當輸入有效的值，你可以再次刪除所有的臨時綁定的東西。

我這裏用的是什麼，我認爲一個不好的做法（但它是從什麼好）：現在

/// <summary> 
    /// Marks a textBox control as invalid (via validation error) from code. 
    /// </summary> 
    /// <param name="textBox">The text box.</param> 
    /// <param name="errorContent">Content of the error.</param> 
    public static void ValidationMarkInvalid(TextBox textBox, String errorContent) 
    { 
     DependencyProperty textProp = TextBox.TextProperty; 
     if (!BindingOperations.IsDataBound(textBox, textProp)) 
     { 
      if (textBox.DataContext == null) 
      { 
       textBox.DataContext = new EmptyDataContext(); 
      } 

      Binding b = new Binding("CodeBehind"); 
      b.FallbackValue = textBox.Text; 
      b.ValidatesOnExceptions = true; 
      BindingOperations.SetBinding(textBox, textProp, b); 
     } 

     BindingExpression bindingInError = 
      textBox.GetBindingExpression(TextBox.TextProperty); 

     var validationError = new ValidationError(
      new EmptyValidationRule(), 
      bindingInError, 
      errorContent, 
      new Exception(errorContent)); 

     Validation.MarkInvalid(bindingInError, validationError); 
    } 

    /// <summary> 
    /// Clears the validation error from a textBox. 
    /// </summary> 
    /// <param name="textBox">The text box.</param> 
    public static void ValidationClear(TextBox textBox) 
    { 
     DependencyProperty textProp = TextBox.TextProperty; 
     if (BindingOperations.IsDataBound(textBox, textProp)) 
     { 
      String value = textBox.Text; 
      Validation.ClearInvalid(textBox.GetBindingExpression(TextBox.TextProperty)); 
      BindingOperations.ClearBinding(textBox, textProp); 
      textBox.Text = value; 

      EmptyDataContext ctx = textBox.DataContext as EmptyDataContext; 
      if (ctx != null) 
      { 
       textBox.DataContext = null; 
      } 
     } 
    } 

    #region Nested Type: EmptyDataContext 
    private sealed class EmptyDataContext : INotifyPropertyChanged 
    { 
     public Object CodeBehind 
     { 
      get 
      { 
       throw new FormatException(); 
      } 
      set 
      { 
       throw new FormatException(); 
      } 
     } 

     #region INotifyPropertyChanged Members 
     public event PropertyChangedEventHandler PropertyChanged; 
     #endregion 
    } 
    #endregion 

    #region Nested Type: EmptyValidationRule 
    private sealed class EmptyValidationRule : ValidationRule 
    { 
     /// <summary> 
     /// When overridden in a derived class, performs validation checks on a value. 
     /// </summary> 
     /// <param name="value">The value from the binding target to check.</param> 
     /// <param name="cultureInfo">The culture to use in this rule.</param> 
     /// <returns> 
     /// A <see cref="T:System.Windows.Controls.ValidationResult"/> object. 
     /// </returns> 
     public override ValidationResult Validate(Object value, CultureInfo cultureInfo) 
     { 
      return new ValidationResult(false, String.Empty); 
     } 
    } 
    #endregion 

，從代碼隱藏你這樣做：

ValidationMarkInvalid(textBox, "Please enter something valid!"); 

，並清除驗證：

ValidationClear(textBox); 

PS：如果你不想驗證例外，你可以從上面的方法中刪除EmptyDataContext類。