Question

我想在DataGrid中显示文件的内容。（该文件包含超过200,000行）

显示带有数据的网格很快。

但是当我使用滚动条（向下滚动）时，我遇到以下异常：

System.InvalidOperationException:
{"An ItemsControl is inconsistent with its items source.\n  See the inner exception for more information."}

的InnerException：

Information for developers (use Text Visualizer to read this):
This exception was thrown because the generator for control 'System.Windows.Controls.DataGrid Items.Count:0' with name '(unnamed)' has received sequence of CollectionChanged events that do not agree with the current state of the Items collection.  The following differences were detected:
  Accumulated count 0 is different from actual count 200000.  [Accumulated count is (Count at last Reset + #Adds - #Removes since last Reset).]

One or more of the following sources may have raised the wrong events:
     System.Windows.Controls.ItemContainerGenerator
      System.Windows.Controls.ItemCollection
       System.Windows.Data.ListCollectionView
        System.Collections.Generic.List`1[[WpfApplication3.Entry, WpfApplication3, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]
(The starred sources are considered more likely to be the cause of the problem.)

The most common causes are (a) changing the collection or its Count without raising a corresponding event, and (b) raising an event with an incorrect index or item parameter.

The exception's stack trace describes how the inconsistencies were detected, not how they occurred.  To get a more timely exception, set the attached property 'PresentationTraceSources.TraceLevel' on the generator to value 'High' and rerun the scenario.  One way to do this is to run a command similar to the following:
   System.Diagnostics.PresentationTraceSources.SetTraceLevel(myItemsControl.ItemContainerGenerator, System.Diagnostics.PresentationTraceLevel.High)
from the Immediate window.  This causes the detection logic to run after every CollectionChanged event, so it will slow down the application.

Exception告诉它：“收到的CollectionChanged事件序列与Items集合的当前状态不一致。”

这是代码：

MainWindow.xaml

<Window x:Class="WpfApplication3.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:WpfApplication3="clr-namespace:WpfApplication3"
        Title="MainWindow" Height="350" Width="525">
    <Grid Name="Test">
        <WpfApplication3:Viewer x:Name="LogUC" />
    </Grid>
</Window>

MainWindow.xaml.cs

public partial class MainWindow
{
    public MainWindow()
    {
        InitializeComponent();
        Test.DataContext = this;

        LogUC.Loaded += LogUcOnLoaded;
    }

    private void LogUcOnLoaded(object sender, RoutedEventArgs routedEventArgs)
    {
        LogUC.Test();
    }
}

Viewer.xaml

<UserControl x:Class="WpfApplication3.Viewer"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Height="300" Width="300">
    <Grid Name="Container">
        <DataGrid ItemsSource="{Binding Path=EntryCollection, Mode=OneTime}"
                  AutoGenerateColumns="False"
                  CanUserResizeColumns="True"
                  CanUserResizeRows="True"
                  CanUserAddRows="False"
                  CanUserDeleteRows="False"
                  IsReadOnly="True">
            <DataGrid.Columns>
                <DataGridTextColumn Binding="{Binding ErrorCode}" Header="" />
                <DataGridTextColumn Binding="{Binding Time}" Header="Time" />
                <DataGridTextColumn Binding="{Binding Content}" Header="Content" />
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</UserControl>

Viewer.xaml.cs

public partial class Viewer : INotifyPropertyChanged
{
    public Viewer()
    {
        EntryCollection = new List<Entry>();
        InitializeComponent();
        Container.DataContext = this;
    }

    public List<Entry> EntryCollection { get; set; }

    internal void Test()
    {
        List<Entry> test = new List<Entry>();

        for (int i = 0; i < 200000; i++)
        {
            Entry entry = new Entry(){
                ErrorCode = 0,
                Time = DateTime.Now.ToString(),
                Content = "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet."
            };
            test.Add(entry);
        }

        EntryCollection.AddRange(test);
        OnPropertyChanged("EntryCollection");
    }

    #region Implementation of INotifyPropertyChanged

    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    #endregion Implementation of INotifyPropertyChanged
}

Entry.cs

public class Entry
{
    public int ErrorCode { get; set; }

    public string Time { get; set; }

    public string Content { get; set; }
}

有什么问题？

Answer 1

我不确定为什么会这样，但我可以告诉你如何让它发挥作用。

通过引发适当的事件，您似乎永远不会告诉DataGrid EntryCollection中的项目已更改。

OnPropertyChanged("EntryCollection")方法中的Test调用无效，因为您在DataGrid绑定上有Mode=OneTime，并且EntryCollection对象是List 1}}而不是ObservableCollection，向其添加项目不会引发任何事件来通知DataGrid。

我看到它的方式，你可以做两件事来解决这个问题。

将EntryCollection设为ObservableCollection，以便在添加/删除项目时通知DataGrid。然后，您可以移除OnPropertyChanged来电，但仍然有Mode=OneTime。

public Viewer()
{
    EntryCollection = new ObservableCollection<Entry>();
    InitializeComponent();
    Container.DataContext = this;
}

public ObservableCollection<Entry> EntryCollection { get; set; }

internal void Test()
{
    for (int i = 0; i < 200000; i++)
    {
        Entry entry = new Entry()
        {
            ErrorCode = 0,
            Time = DateTime.Now.ToString(),
            Content = "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet."
        };

        EntryCollection.Add(entry);
    }
}

不是将项目添加到EntryCollection，而是将其设置为新实例并引发PropertyChanged事件。这样做，您需要删除XAML中的Mode=OneTime设置。

public Viewer()
{
    EntryCollection = new List<Entry>();    
    InitializeComponent();
    Container.DataContext = this;
}

public List<Entry> EntryCollection { get; set; }

internal void Test()
{
    List<Entry> test = new List<Entry>();

    for (int i = 0; i < 200000; i++)
    {
        Entry entry = new Entry()
        {
            ErrorCode = 0,
            Time = DateTime.Now.ToString(),
            Content = "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet."
        };
        test.Add(entry);    
    }

    EntryCollection = test;
    OnPropertyChanged("EntryCollection");
}

DataGrid通过滚动抛出InvalidOperationException

1 个答案: