綁定的ObservableCollection更改時，ListView不更新

Question

我正在使用一個搜索窗口，它將搜索結果加載到ObservableCollection中，然后使用ListView顯示結果。

搜索完成后，將ListView的ItemSource設置為ObservableCollection可以正確填充列表。

我正在嘗試更新ListView，因為搜索添加了其他結果，但是ListView根本沒有填充任何數據。 我無法解決我的綁定丟失的地方。

我的研究顯示了使用DataContext的各種方法，盡管似乎沒有幫助。 我嘗試使用CodeBehind以及xaml Window級別將其分配給“ this”和CachedData類。

很抱歉，很長的代碼片段，我遺漏了我認為可能有助於在問題中添加上下文的任何內容。

XAML：

<Window x:Class="SLX_Interface.MainWindow"
    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:local="clr-namespace:SLX_Interface"
    mc:Ignorable="d"
    Title="SLX Search" Height="auto" Width="auto">
<Window.CommandBindings>
</Window.CommandBindings>
<Grid>
    <Grid.Resources>
        <local:CachedData x:Key="cachedData" />
    </Grid.Resources>
    <TabControl x:Name="tabControl" Grid.RowSpan="2" Margin="0,20,0,0">
        <TabItem Header="Accounts" Name="accountsTab">
            <Grid>
                <ListView x:Name="accountSearchResultsListView" Margin="5,32,5,30" DataContext="staticResource cachedData" ItemsSource="{Binding Path=accounts}" IsSynchronizedWithCurrentItem="True">
                    <ListView.View>
                        <GridView x:Name="accountSearchResultsGridView">
                            <GridViewColumn Header="SData Key" DisplayMemberBinding="{Binding SDataKey}"/>
                            <GridViewColumn Header="Account Name" DisplayMemberBinding="{Binding AccountName}"/>
                        </GridView>
                    </ListView.View>
                </ListView>
             </Grid>
        </TabItem>
    </TabControl>
</Grid>

從MainWindow.xaml.cs內部進行代碼隱藏：

private async void SearchAccount(string searchTerm, string searchField, string searchOperator)
    {
        //Create the string we'll use for searching
        string urlString = "Stuff";

        //Create an ObservableCollection, then use it to blank the cache
        ObservableCollection<Account> resultsList = new ObservableCollection<Account>();
        CachedData.accounts = resultsList;

        //Getting data from the search using an XML Reader
        XmlReader resultsReader = null;

        try
        {
            //Using XmlReader to grab the search results from SLX
            XmlUrlResolver resultsResolver = new XmlUrlResolver();
            resultsResolver.Credentials = LoginCredentials.userCred;

            XmlReaderSettings resultsReaderSettings = new XmlReaderSettings();
            resultsReaderSettings.XmlResolver = resultsResolver;
            resultsReaderSettings.Async = true;

            resultsReader = XmlReader.Create(urlString, resultsReaderSettings);
        }
        catch (Exception error)
        {

        }

        //Grabbing data from the XML and storing it, hopefully updating the ListView as we go
        using (resultsReader)
        {
            while (await resultsReader.ReadAsync())
            {
                while (resultsReader.ReadToFollowing("slx:Account"))
                {
                    //Setting data from the XML to a new Account object ready to be passed to the list
                    Account account = new Account();
                    account.GUID = new Guid();

                    resultsReader.MoveToFirstAttribute(); account.SDataKey = resultsReader.Value;
                    resultsReader.ReadToFollowing("slx:AccountName"); account.AccountName = resultsReader.ReadElementContentAsString();

                    CachedData.accounts.Add(account);

                    //--Uncommenting this gives odd results;
                    //--The first item is displayed, any others aren't.
                    //--If there are a lot of items, the application eventually errors like mad and ends.
                    //--Looks like one error window for each item, though I don't see the message before they die along with the application.
                    //accountSearchResultsListView.ItemsSource = CachedData.accounts;
                }
            }
        }

        //--Uncommenting this works but shows the data once the entire XML has been read through, which can take some time so isn't ideal.
        //accountSearchResultsListView.ItemsSource = CachedData.accounts;        }

上面的類引用，存儲在單獨的.cs文件中，但在相同的名稱空間下：

public class CachedData
{
    public static ObservableCollection<Account> accounts { get; set; }

    public static event PropertyChangedEventHandler PropertyChanged;

    public static event EventHandler<PropertyChangedEventArgs> StaticPropertyChanged = delegate { };
    private static void NotifyStaticPropertyChanged(string propertyName)
    {
        StaticPropertyChanged(null, new PropertyChangedEventArgs(propertyName));
    }
}

public class Account : IEquatable<Account>
{
    public Guid GUID { get; set; }
    public string SDataKey { get; set; }
    public string AccountName { get; set; }

    public override string ToString()
    {
        return AccountName;
    }

    public override bool Equals(object obj)
    {
        if (obj == null) return false;
        Account objAsPart = obj as Account;
        if (objAsPart == null) return false;
        else return Equals(objAsPart);
    }

    public override int GetHashCode()
    {
        return 0;
    }

    public bool Equals(Account other)
    {
        if (other == null) return false;
        return (GUID.Equals(other.GUID));
    }
}

我感謝您可以提供的任何幫助，這已經困擾了我好幾天了。

Answer 1

在xaml中設置數據綁定時，將綁定應用程序啟動時存在的ObservableCollection實例。 因此，請務必在應用啟動之前實例化一個實例，並且不要用新實例替換它，除非您在后面的代碼中重置了數據綁定。 如果需要清除其元素，請使用Clear方法。

Answer 2

問題是您使用的是內部實現INotifyCollectionChanged的 ObservableCollection 。 這並不會引起對收藏的任何改變。 僅當添加或從集合中刪除項目時，它才會引發集合更改。

因此，如果有人分配一個新的collection實例（ 視您的情況 ），將會發生問題。 因此重置綁定不是一個很好的選擇，而是可以自己進行更改。 通過簡單地實現INotifyPropertyChanged。（通常情況下）

public class DataClass : INotifyPropertyChanged
{

    public event PropertyChangedEventHandler PropertyChanged;

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


    private ObservableCollection<string> collection;

    public ObservableCollection<string> Collection
    {
        get { return collection; }
        set
        {
            collection = value;
            OnPropertyChanged("Collection");
        }
    }       
}

因此將集合分配為null或新實例也將反映到綁定控件中。 （您已經有了NotifyStaticPropertyChanged，您只需要創建一個完整的屬性，並在需要時提出更改即可。）