【发布时间】：2014-08-31 21:07:35
【问题描述】：
当我通过 XAML 将按钮连接到命令时，出现运行时错误 System.Windows.Markup.XamlParseException：在“System.Windows.Data.Binding”上提供值引发异常。 ---> System.InvalidCastException：无法将“System.Reflection.RuntimeEventInfo”类型的对象转换为“System.Reflection.MethodInfo”类型。
当我删除 XAML 中的命令绑定时，一切正常，并且我的项目显示等。 这是命令绑定：
Click="{Binding ElementName=MainGrid, Path=DataContext.AlertClickCommand}"
连接视图模型的代码（在我的窗口后面的代码中）：
this.AlertsView.DataContext = GlobalStuff.AlertManager1.AlertViewModel1;
这是我的视图模型我的视图模型是我的视图的数据上下文
using System.Collections.Generic;
using System.ComponentModel;
using Arkle.SharedUI.Model;
using Arkle.SharedUI.ViewModel.Commands;
namespace Arkle.SharedUI.ViewModel
{
public class AlertViewModel : INotifyPropertyChanged
{
private List<Alert> _alerts = new List<Alert>();
public List<Alert> Alerts
{
get { return _alerts; }
set
{
_alerts = value;
OnPropertyChanged("Alerts");
}
}
public AlertViewModel()
{
if (DesignerProperties.IsInDesignMode)
{
LoadDesignTimeData();
}
}
private void LoadDesignTimeData()
{
Alerts.Add(new Alert { BackgroundMessage = "Sis", IsAlerting = true, OverlayMessage = "3 mins", Tip = "Sis Data not received for 3 mins" });
Alerts.Add(new Alert { BackgroundMessage = "Bets", IsAlerting = true, OverlayMessage = "4", Tip = "4 unchecked danger bets" });
Alerts.Add(new Alert { BackgroundMessage = "Texts", IsAlerting = false, OverlayMessage = "3", Tip = "3 Unchecked Text Bets" });
}
private AlertClickCommand _alertClickCommand;
public AlertClickCommand AlertClickCommand
{
get { return _alertClickCommand ?? (_alertClickCommand = new AlertClickCommand(this)); }
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
这是我的 xaml
<UserControl x:Class="Arkle.SharedUI.View.AlertsView"
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"
xmlns:viewModel="clr-namespace:Arkle.SharedUI.ViewModel"
mc:Ignorable="d"
d:DataContext="{d:DesignInstance Type=viewModel:AlertViewModel, IsDesignTimeCreatable=True}"
x:Name="EarlyPriceEditorViewModelWindow"
Height="Auto" Width="Auto">
<UserControl.Resources>
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter"/>
</UserControl.Resources>
<Grid Name="MainGrid">
<StackPanel Name="MainStackPanel">
<ListBox ItemsSource="{Binding Path=Alerts}" >
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel Orientation="Horizontal" >
</WrapPanel>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Visibility="{Binding IsAlerting,Converter={StaticResource BooleanToVisibilityConverter}}">
<StackPanel Orientation="Horizontal">
<Button Content="{Binding BackgroundMessage}" HorizontalAlignment="Left" Width="75" VerticalAlignment="Top" Height="Auto" Margin="2"
Click="{Binding ElementName=MainGrid, Path=DataContext.AlertClickCommand}" CommandParameter="{Binding}"
/>
<Label Content="{Binding OverlayMessage}" HorizontalAlignment="Left" Width="Auto" Margin="1,0,0,0" VerticalAlignment="Top" Background="Red" Foreground="White"
FontWeight="Bold">
<Label.Style>
<Style>
<Style.Triggers>
<DataTrigger Binding="{Binding IsAlerting}" Value="True">
<Setter Property="Image.Visibility" Value="Visible" />
<DataTrigger.EnterActions>
<BeginStoryboard x:Name="ImageFlash">
<Storyboard>
<DoubleAnimation Storyboard.TargetProperty="(UIElement.Opacity)"
BeginTime="0:0:0" Duration="0:0:0.5"
From="1.0" To="0.0" RepeatBehavior="Forever" AutoReverse="True"/>
</Storyboard>
</BeginStoryboard>
</DataTrigger.EnterActions>
<DataTrigger.ExitActions>
<StopStoryboard BeginStoryboardName="ImageFlash" />
</DataTrigger.ExitActions>
</DataTrigger>
<DataTrigger Binding="{Binding IsAlerting}" Value="False">
<DataTrigger.Setters>
<Setter Property="Image.Visibility" Value="Collapsed" />
</DataTrigger.Setters>
</DataTrigger>
</Style.Triggers>
</Style>
</Label.Style>
</Label>
<Label Content="|" Margin="5"/>
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</Grid>
</UserControl>
这是我的命令
using System;
using System.Windows.Input;
using Arkle.Common;
using Arkle.SharedUI.Events;
using Arkle.SharedUI.Model;
namespace Arkle.SharedUI.ViewModel.Commands
{
public class AlertClickCommand : ICommand
{
private AlertViewModel _alertViewModel;
public AlertClickCommand(AlertViewModel alertViewModel)
{
_alertViewModel = alertViewModel;
}
public void Execute(object parameter)
{
if (parameter == null)
{
return;
}
var parameterAsAlert = (Alert)parameter;
switch (parameterAsAlert.BackgroundMessage)
{
case "Bets":
EventManager.Instance.GetEvent<ShowDangerBetsRequestedEvent>().Publish(null);
break;
default:
return;
}
}
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged;
}
}
我还收到以下设计时错误（见屏幕截图） 无法将“System.Windows.Data.Binding”类型的对象转换为“Microsoft.Expression.Markup.DocumentModel.DocumentNode”类型。
第一个运行时错误 - 引发运行
重复抛出后续运行时错误： System.Windows.Markup.XamlParseException：在“System.Windows.Data.Binding”上提供值引发异常。 ---> System.InvalidCastException：无法将“System.Reflection.RuntimeEventInfo”类型的对象转换为“System.Reflection.MethodInfo”类型。
在 MS.Internal.Helper.CheckCanReceiveMarkupExtension(MarkupExtension markupExtension, IServiceProvider serviceProvider, DependencyObject& targetDependencyObject, DependencyProperty& targetDependencyProperty)
在 System.Windows.Data.BindingBase.ProvideValue(IServiceProvider serviceProvider)
在 MS.Internal.Xaml.Runtime.ClrObjectRuntime.CallProvideValue(MarkupExtension me, IServiceProvider serviceProvider)
---内部异常堆栈跟踪结束---
在 System.Windows.FrameworkTemplate.LoadTemplateXaml(XamlReader templateReader, XamlObjectWriter currentWriter)
.......................
【问题讨论】：
-
您在哪里以及如何设置您的
DataContext？您的视图模型代码（至少是属性）在哪里？看在上帝的份上，请删除那个可笑的长堆栈跟踪，除非您打算让用户阅读您的问题。 -
嗨，我已经修改了问题以显示正在设置的数据上下文。
标签： c# wpf xaml binding command