如何在WPF输出窗口中消除绑定“信息” - 无法使用绑定检索值 [英] How to eliminate Binding “Information” in WPF output window - cannot retrieve value using the binding

问题描述

我正在写一个WPF应用程序，性能有点慢，所以我试图解决它。当我运行时，我大概收到这些类型的消息：

  System.Windows.Data信息：10：无法检索存在使用绑定的值，并且没有有效的后备值存在;使用默认代替。 BindingExpression：路径=（0）; DataItem = null;目标元素为Control（Name ='）;目标属性为可见性（类型可见性）
 System.Windows.Data信息：10：无法使用绑定检索值，并且不存在有效的后备值;使用默认代替。 BindingExpression：Path = AreRowDetailsFrozen; DataItem = null; target元素是'DataGridDetailsPresenter'（Name =''）; target属性为SelectiveScrollingOrientation（键入SelectiveScrollingOrientation）
 System.Windows.Data信息：10：无法使用绑定检索值，并且不存在有效的后备值;使用默认代替。 BindingExpression：Path = HeadersVisibility; DataItem = null; target元素是'DataGridRowHeader'（Name =''）;目标属性为可见性（类型可见性）
 System.Windows.Data信息：10：无法使用绑定检索值，并且不存在有效的后备值;使用默认代替。绑定表达式：Path = ValidationErrorTemplate; DataItem = null;目标元素为Control（Name ='）;目标属性是模板（类型'ControlTemplate'）
  

如果我做一个例子应用程序： / p>

 < Window x：Class =bindingerrors.MainWindow
 xmlns =http://schemas.microsoft。 com / winfx / 2006 / xaml / presentation
 xmlns：x =http://schemas.microsoft.com/winfx/2006/xaml
 xmlns：bindingerrors =clr-namespace：bindingerrors Title =MainWindow> 
< Window.Resources> 
< bindingerrors：Thinger x：Key =Thing/> 
< /Window.Resources> 
< StackPanel> 
< DataGrid x：Name =TheGridItemsSource ={Binding Stuff，Source = {StaticResource Thing}}AutoGenerateColumns =FalseHeadersVisibility =Column> 
< DataGrid.Columns> 
< DataGridTextColumn Header =！ Binding ={Binding A，FallbackValue =''}/> 
< DataGridTextColumn Header =＃Binding ={Binding I，FallbackValue =''}/> 
< /DataGrid.Columns> 
< / DataGrid> 
< / StackPanel> 
< / Window> 
  

以下对象定义：

  public class Thinger 
 {
 public ObservableCollection< ARow>东西{get;私人集合
 
 public Thinger（）
 {
 //填写一些虚假数据
 string letters =ABCDEFGHIJKLMNOPQRSTUVWXYZ; 
 int i = 0; 
 Stuff = new ObservableCollection< ARow>（）; 
 foreach（var letter in letters）
 {
 Stuff.Add（new ARow（letter.ToString（），i））; 
 i ++; 
} 
} 
} 
 
 public class ARow 
 {
 public string A {get;私人集合} 
 public int I {get;组; 
 
 public ARow（string a，int i）
 {
 A = a; 
 I = i; 
} 
} 
  

执行时，我遇到了这些绑定问题的山峰。由于许多WPF性能文章声称失败的绑定可能会严重影响性能，我怀疑这可能是我的许多问题的根源。

发生了什么？如何消除这些失败的绑定？我提供的例子就像我可以做到的一样简单，同时仍然是问题的症状，但它应该只是工作，不应该吗？我正在构建.net 4.0，如果这有任何区别。

编辑：如果您尝试构建示例，则可能会抑制错误码。在可视化工作室选项 - >调试 - >输出窗口 - >数据绑定中，看到它设置在信息上。

我看到获取许多绑定信息在WPF输出窗口，但是没有关于它在那里做什么的信息。

谢谢

解决方案

有一些事情可以解决，以消除一些错误。

1. Stuff 有一个私人设置器，所以你必须设置
   BindingMode 到 OneWay


2. A 有一个私人设置器，所以你必须设置
   BindingMode 至 OneWay


3. I 具有不是 int 的回退值

但是，这些都不符合您发布的错误，但只是一些观察

I am writing a WPF application, and performance is it is a bit slow, and so I am trying to solve it. When I run, I get roughly a gazillion of these types of messages:

System.Windows.Data Information: 10 : Cannot retrieve value using the binding and no valid fallback value exists; using default instead. BindingExpression:Path=(0); DataItem=null; target element is 'Control' (Name=''); target property is 'Visibility' (type 'Visibility')
System.Windows.Data Information: 10 : Cannot retrieve value using the binding and no valid fallback value exists; using default instead. BindingExpression:Path=AreRowDetailsFrozen; DataItem=null; target element is 'DataGridDetailsPresenter' (Name=''); target property is 'SelectiveScrollingOrientation' (type 'SelectiveScrollingOrientation')
System.Windows.Data Information: 10 : Cannot retrieve value using the binding and no valid fallback value exists; using default instead. BindingExpression:Path=HeadersVisibility; DataItem=null; target element is 'DataGridRowHeader' (Name=''); target property is 'Visibility' (type 'Visibility')
System.Windows.Data Information: 10 : Cannot retrieve value using the binding and no valid fallback value exists; using default instead. BindingExpression:Path=ValidationErrorTemplate; DataItem=null; target element is 'Control' (Name=''); target property is 'Template' (type 'ControlTemplate')

If I make a little example application:

<Window x:Class="bindingerrors.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:bindingerrors="clr-namespace:bindingerrors" Title="MainWindow">
    <Window.Resources>
        <bindingerrors:Thinger x:Key="Thing" />               
    </Window.Resources>
    <StackPanel>
        <DataGrid x:Name="TheGrid" ItemsSource="{Binding Stuff, Source={StaticResource Thing}}" AutoGenerateColumns="False" HeadersVisibility="Column">
            <DataGrid.Columns>
                <DataGridTextColumn Header="!" Binding="{Binding A, FallbackValue=''}" />
                <DataGridTextColumn Header="#" Binding="{Binding I, FallbackValue=''}" />              
                </DataGrid.Columns>
        </DataGrid>
    </StackPanel>
</Window>

And the following object definitions:

public class Thinger
{
    public ObservableCollection<ARow> Stuff { get; private set; }

    public Thinger()
    {
        //Fill up some bogus data
        string letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        int i = 0;
        Stuff = new ObservableCollection<ARow>();
        foreach (var letter in letters)
        {
            Stuff.Add(new ARow(letter.ToString(),i));
            i++;
        }
    }
}

public class ARow
{
    public string A { get; private set; }
    public int I { get; set; }

    public ARow(string a, int i)
    {
        A = a;
        I = i;
    }
}

Upon execution, I get mountains of those binding problems. Because many WPF performance articles claim that failed bindings can seriously hurt performance, I suspect this may be the source of many of my problems.

What is going on? How can I eliminate these failed bindings? The example I provided is as simple as I could make it while still being symptomatic of the problem, but it should just work, shouldn't it? I'm building for .net 4.0, if that makes any difference.

edit: The errors may be suppressed if you try building the sample code. In visual studio options -> debugging -> output window -> databinding, see that it is set on "Information".

I have seen Getting many Binding "Information" in WPF output window, but there is no information on what to do about it in there.

Thanks

解决方案

Well there are a few things you can fix to eliminate some of those errors.

1. Stuff has a private setter so you will have to set the BindingMode to OneWay
2. A has a private setter so you will have to set the BindingMode to OneWay
3. I has a fallback value that is not an int value

However none of these match the errors you posted, but just some observations

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