爲什麼IDataErrorInfo多次觸發？

我遇到了IDataErrorInfo多次被解僱的問題。爲什麼IDataErrorInfo多次觸發？

Transaction Class

public class Transaction : INotifyPropertyChanged, INotifyPropertyChanging, IDataErrorInfo 
{ 

private Double? _transAmount; 

[Column(DbType = "decimal(19,4)")] 
public Double? TransAmount 
{ 
    get { return _transAmount; } 
    set 
    { 
     if (_transAmount != value) 
     { 
      NotifyPropertyChanging("TransAmount"); 
      _transAmount = value; 
      NotifyPropertyChanged("TransAmount"); 
     } 
    } 
} 

#region INotifyPropertyChanged Members 

public event PropertyChangedEventHandler PropertyChanged; 

// Used to notify that a property changed 
private void NotifyPropertyChanged(string propertyName) 
{ 
    if (PropertyChanged != null) 
    { 
     PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 
    } 
} 

#endregion 

#region INotifyPropertyChanging Members 

public event PropertyChangingEventHandler PropertyChanging; 

// Used to notify that a property is about to change 
private void NotifyPropertyChanging(string propertyName) 
{ 
    if (PropertyChanging != null) 
    { 
     PropertyChanging(this, new PropertyChangingEventArgs(propertyName)); 
    } 
} 

#endregion 

#region Data Validation 

public string Error { get { return null; } } 

public string this[string property] 
{ 
    get 
    { 
     switch (property) 
     { 
      case "TransAmount": 
       if (TransAmount != null) 
       { 
        double value; 
        bool valid = double.TryParse(TransAmount.ToString(), out value); 

        if (!valid) { return TransAmount.ToString() + " is not a valid number"; } 
        else if (value <= 0) { return "Dollar amount must be greater than $0.00"; } 
       } 
       return null; 
      default: 
       return null; 
     } 
    } 
} 

#endregion 

}

和XAML

<toolkit:PhoneTextBox Grid.Row="1" Grid.Column="1" HorizontalAlignment="Stretch" 
         x:Name="txtAmount" Width="Auto" 
         Text="{Binding TransAmount, Mode=TwoWay, NotifyOnValidationError=True, StringFormat=\{0:c\}, ValidatesOnDataErrors=True, ValidatesOnExceptions=True}" 
         BindingValidationError="txtAmount_BindingValidationError" InputScope="CurrencyAmount" 
         GotFocus="txtAmount_GotFocus" 
         LostFocus="txtAmount_LostFocus"> 
</toolkit:PhoneTextBox>

我不知道的格局，但驗證方法被擊中的2-3倍？爲什麼？

編輯1 正在txtAmount_LostFocus事件中設置值TransAmount。

編輯2 加入WP7標籤

來源

2011-09-26 Tim Gabrhel

它不應該不管有多少次火災。造成什麼問題？ – Bryant

實際上WPF驗證框架並不「保證」整個「依賴」框架的單一驗證通行證。嘗試提高您的驗證代碼速度。 –

@Bryant - 這是在WP7上（只是添加了標籤），我不知道如何向用戶展示錯誤。爲了看到一個錯誤，我在上面的文本框中添加了一個事件處理函數'BindingValidationError'。這會彈出一個消息框，顯示IDataErrorInfo返回的錯誤的內容。也許這是一個不正確的實現。 –

訣竅如下。

使用DataErrorValidationRule代替ValidatesOnDataErrors = True。

<TextBox> 
    <TextBox.Text> 
     <Binding Path="..." UpdateSourceTrigger="LostFocus" NotifyOnValidationError="True"> 
       <Binding.ValidationRules> 
        <DataErrorValidationRule ValidatesOnTargetUpdated="False"/> 
       </Binding.ValidationRules> 
      </Binding> 
    </TextBox.Text> 
</TextBox>

請參閱本文https://social.msdn.microsoft.com/forums/vstudio/en-US/099164f8-72aa-4c59-a7b6-7ccbd56702ce/idataerrorinfo-validation-called-twice

來源

2015-03-11 10:14:19 kbisang

爲什麼IDataErrorInfo多次觸發？

回答

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