WPF验证不会触发TextBox的第一个LostFocus [英] WPF Validation Not Firing on First LostFocus of the TextBox

问题描述

我试图验证对象的WPF形式。当我在文本框中输入某些东西时，验证会激发失去焦点回到文本框，然后擦除我写的任何东西。但是，如果我只是加载WPF应用程序和标签关闭文本框没有写入和从文本框中删除任何东西，那么它不会被解雇。

以下是Customer.cs类：

  public class Customer ：IDataErrorInfo 
 {
 public string FirstName {get;组; } 
 public string LastName {get;组; } 
 
 public string Error 
 {
 get {throw new NotImplementedException（）; } 
 
 public string this [string columnName] 
 {
 get 
 {
 string result = null; 
 $ b $ if（columnName.Equals（FirstName））
 {
 if（String.IsNullOrEmpty（FirstName））
 {
 result =FirstName不能为空或空。 
 
 
 if（columnName.Equals（LastName））
 {
 if（String.IsNullOrEmpty（LastName））
 {
结果=姓氏不能为空或空白; 
} 
} 
返回结果; 
 
 
 
 
 
 
这里是WPF代码：
 < TextBlock Grid.Row =1Margin =10Grid.Column =0> LastName< ; / TextBlock的> 
< TextBox Style ={StaticResource textBoxStyle}Name =txtLastNameMargin =10
 VerticalAlignment =TopGrid.Row =1Grid.Column =1> 
< Binding Source ={StaticResource CustomerKey}Path =LastName
 ValidatesOnExceptions =TrueValidatesOnDataErrors =True
 UpdateSourceTrigger =LostFocus/> 
< / TextBox> 
  
 
 
解决方案
在你的代码背后的逻辑，你可以像这样处理实际的 LostFocus 事件： 
 $ b   .xaml  
 < TextBox LostFocus =TextBox_LostFocus.... 
  
 
 
 
  .xaml.cs  
（（Control）sender）.GetBindingExpression（TextBox.TextProperty）.UpdateSource（）; p $ p $ {code> private void TextBox_LostFocus（object sender，RoutedEventArgs e） 
} 
  
 
I am trying to validate the WPF form against an object. The validation fires when I type something in the textbox lose focus come back to the textbox and then erase whatever I have written. But if I just load the WPF application and tab off the textbox without writing and erasing anything from the textbox, then it is not fired. 

Here is the Customer.cs class: 
public class Customer : IDataErrorInfo
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }

        public string Error
        {
            get { throw new NotImplementedException(); }
        }
        public string this[string columnName]
        {
            get
            {
                string result = null;

                if (columnName.Equals("FirstName"))
                {
                    if (String.IsNullOrEmpty(FirstName))
                    {
                        result = "FirstName cannot be null or empty"; 
                    }
                }
                else if (columnName.Equals("LastName"))
                {
                    if (String.IsNullOrEmpty(LastName))
                    {
                        result = "LastName cannot be null or empty"; 
                    }
                }
                return result;
            }
        }
    }
And here is the WPF code: 
<TextBlock Grid.Row="1" Margin="10" Grid.Column="0">LastName</TextBlock>
<TextBox Style="{StaticResource textBoxStyle}" Name="txtLastName" Margin="10"
         VerticalAlignment="Top" Grid.Row="1" Grid.Column="1">
    <Binding Source="{StaticResource CustomerKey}" Path="LastName"
             ValidatesOnExceptions="True" ValidatesOnDataErrors="True"
             UpdateSourceTrigger="LostFocus"/>         
</TextBox>

解决方案
If you're not adverse to putting a bit of logic in your code behind, you can handle the actual LostFocus event with something like this:

.xaml
<TextBox LostFocus="TextBox_LostFocus" ....




.xaml.cs
private void TextBox_LostFocus(object sender, RoutedEventArgs e)
{
     ((Control)sender).GetBindingExpression(TextBox.TextProperty).UpdateSource();
}


                        
这篇关于WPF验证不会触发TextBox的第一个LostFocus的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！