在UserControl中显示验证错误
在UserControl中显示验证错误
提问于 2010-11-13 03:44:23
我不确定为什么验证状态没有反映在我的用户控件中。我抛出了一个异常，但由于某种原因，控件没有显示验证state...When，我在MainPage上使用了一个标准的Textbox (在我的例子中，它现在已经被注释掉了)，它显示了错误状态，不知道为什么它没有包装。
我已经精简了它，所以基本上它是一个包装了TextBox的用户控件。我遗漏了什么？?
MyUserControl XAML：
<UserControl x:Class="ValidationWithUserControl.MyUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
<TextBox x:Name="TextBox"/>
</Grid>
</UserControl>背后的MyUserControl代码：
public partial class MyUserControl : UserControl
{
public MyUserControl()
{
InitializeComponent();
this.Loaded += new RoutedEventHandler(MyUserControl_Loaded);
this.TextBox.Unloaded += new RoutedEventHandler(TextBox_Unloaded);
}
public string Value
{
get { return (string)base.GetValue(ValueProperty); }
set { base.SetValue(ValueProperty, value); }
}
public static DependencyProperty ValueProperty =
DependencyProperty.Register(
"Value",
typeof(string),
typeof(MyUserControl),
new PropertyMetadata(null));
private void MyUserControl_Loaded(object sender, RoutedEventArgs e)
{
this.TextBox.SetBinding(TextBox.TextProperty, new Binding()
{
Source = this,
Path = new PropertyPath("Value"),
Mode = BindingMode.TwoWay,
ValidatesOnExceptions = true,
NotifyOnValidationError= true
});
}
private void TextBox_Unloaded(object sender, RoutedEventArgs e)
{
this.TextBox.ClearValue(TextBox.TextProperty);
}
}我的MainPage XAML：
<Grid x:Name="LayoutRoot" Background="LightBlue">
<StackPanel>
<uc:MyUserControl x:Name="UC" Value="{Binding Path=Value, Mode=TwoWay}" Height="20" Width="100" />
<!--TextBox x:Name="MS" Text="{Binding Path=Value, Mode=TwoWay, ValidatesOnExceptions=True, NotifyOnValidationError=True}" Height="20" Width="100" /-->
</StackPanel>
</Grid>我的MainPage代码背后：
public partial class MainPage : UserControl
{
private Model model;
//private Model model2;
public MainPage()
{
InitializeComponent();
this.model = new Model("UC");
//this.model2 = new Model("MS");
this.UC.DataContext = this.model;
//this.MS.DataContext = this.model2;
}
}我的模型：
public class Model
{
public Model(string answer)
{
this.answer = answer;
}
private string answer;
public string Value
{
get
{
return this.answer;
}
set
{
if (!String.IsNullOrEmpty(value))
this.answer = value;
else
throw new Exception("Error");
}
}
}回答 2
Stack Overflow用户
发布于 2018-12-20 04:34:58
您应该能够回显直接绑定到用户控件文本框的依赖属性。这将像父视图中的绑定一样拾取验证错误。在您的MyUserControl_Loaded函数中：
var valueBinding = BindingOperations.GetBindingBase(this, ValueProperty);
if (valueBinding != null) TextBox.SetBinding(TextBox.TextProperty, valueBinding);Stack Overflow用户
发布于 2016-12-13 19:14:31
如果有人来为这个问题寻找一个好的解决方案(请阅读：“不是用VBA语言编写的并且完整的”)，我基于@UserControl_Black_蓝精灵在C#中的回答写了一个base class (虽然我只用无外观控件测试过，但不知道它是否适用于UserControls)：
namespace MyApplication.Controls
{
using System;
using System.Collections;
using System.ComponentModel;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
public abstract class ControlBaseWithValidation : Control, INotifyDataErrorInfo
{
public ControlBaseWithValidation()
{
// remove the red border that wraps the whole control by default
Validation.SetErrorTemplate(this, null);
}
public delegate void ErrorsChangedEventHandler(object sender, DataErrorsChangedEventArgs e);
public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
public bool HasErrors
{
get
{
var validationErrors = Validation.GetErrors(this);
return validationErrors.Any();
}
}
public IEnumerable GetErrors(string propertyName)
{
var validationErrors = Validation.GetErrors(this);
var specificValidationErrors =
validationErrors.Where(
error => ((BindingExpression)error.BindingInError).TargetProperty.Name == propertyName).ToList();
var specificValidationErrorMessages = specificValidationErrors.Select(valError => valError.ErrorContent);
return specificValidationErrorMessages;
}
public void NotifyErrorsChanged(string propertyName)
{
if (ErrorsChanged != null)
{
ErrorsChanged(this, new DataErrorsChangedEventArgs(propertyName));
}
}
protected static void ValidatePropertyWhenChangedCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
{
((ControlBaseWithValidation)dependencyObject).NotifyErrorsChanged(dependencyPropertyChangedEventArgs.Property.Name);
}
}
}使用ControlBaseWithValidation类作为无外观控件的基类，而不是Control类，并在要验证的任何依赖属性上添加ValidatePropertyWhenChangedCallback回调作为PropertyChangedCallback。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/4168438
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