我有一个相当混乱的情况:
我打开一个对话框,显示一个INotifyDataErrorInfo
立即返回错误的视图(当文本字段不为空时),我看到红色边框错误通知器:
开幕#1:
我什么都不做并关闭窗口,然后再次单击打开按钮:
开幕#2:
有没有搞错?我检查了错误标志,它已设置。当我删除文本并写回内容时,错误边框会重新出现,因为错误条件会检查string empty? error: no error
这是一个小的复制案例:
编辑:我添加了 ViewModel,它在每个节目中创建,导致 INCP 更改事件
主窗口.xaml.cs
using System;
using System.Collections;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
namespace LayoutBreakerMinimal
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void ButtonBase_OnClick( object sender, RoutedEventArgs e )
{
var w = new Window();
var v = Resources["OneInstanceView"] as View; // new View(); <-- would work
w.Content = v;
v.DataContext = new ViewModel();
w.ShowDialog();
}
}
public partial class View : UserControl
{
public View()
{
InitializeComponent();
}
}
public partial class ViewModel : INotifyDataErrorInfo, INotifyPropertyChanged
{
private string _myTextField;
public ViewModel()
{
MyTextField = "Error field";
}
public string MyTextField
{
get { return _myTextField; }
set
{
_myTextField = value;
OnPropertyChanged();
if ( ErrorsChanged != null ) ErrorsChanged( this, new DataErrorsChangedEventArgs( "MyTextField" ) );
}
}
public IEnumerable GetErrors( string propertyName )
{
yield return "Field is null";
}
public bool HasErrors
{
get { return MyTextField != ""; }
}
public event EventHandler< DataErrorsChangedEventArgs > ErrorsChanged;
protected virtual void OnPropertyChanged( [CallerMemberName] string propertyName = null )
{
var handler = PropertyChanged;
if ( handler != null ) handler( this, new PropertyChangedEventArgs( propertyName ) );
}
public event PropertyChangedEventHandler PropertyChanged;
}
}
主窗口.xaml
<Window x:Class="LayoutBreakerMinimal.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:layoutBreakerMinimal="clr-namespace:LayoutBreakerMinimal"
Title="MainWindow" Height="350" Width="525">
<Window.Resources>
<layoutBreakerMinimal:View x:Key="OneInstanceView" />
</Window.Resources>
<Grid>
<Button Click="ButtonBase_OnClick" Margin="40">Open Dialog, then open it again</Button>
</Grid>
</Window>
查看.xaml
<UserControl x:Class="LayoutBreakerMinimal.View"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<StackPanel>
<TextBox Text="{Binding MyTextField, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, NotifyOnValidationError=True}" Height="30" Width="100"></TextBox>
<Label Content="{Binding HasErrors}" Height="30" Width="100"></Label>
</StackPanel>
</UserControl>
我无法理解为什么边界会消失。
我发现:如果我每次都创建新视图(而不是单个资源实例),那么每次从一开始就可以使用红色边框。
我测试了将其移动INotifyDataErrorInfo
到一个单独的ViewModel
中,每次 new 时都会实例化 -> 不走运。
编辑 2:我在视图中添加了 HasError 标签以指示它一直显示错误