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我在列表视图中有一个按钮，当我单击该按钮时，数据模板应将值加 1。我只想更新特定的行，但是当我单击按钮时，所有行都会更新。有人能帮我吗？尝试了许多解决方案，但它根本无法工作。这些是我的 xaml 代码

<ListView.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal" Width="1048" Height="158">
                <StackPanel.Background>
                    <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                        <GradientStop Color="White" Offset="0.971"/>
                        <GradientStop Color="#FF929990" Offset="1"/>
                    </LinearGradientBrush>
                </StackPanel.Background><Button x:Name="btnVote" BorderBrush="Black" BorderThickness="2" Height="45" Margin="0,70,0,43" Width="78" Content="Vote" Background="Black" Click="btnVote_Click" />
                <Image HorizontalAlignment="Left" Height="111" Margin="10,10,0,0" Grid.Row="1" VerticalAlignment="Top" Width="118" Source="{Binding Img}"/>
                <HyperlinkButton Tag="{Binding UserID}" FontSize="20" ScrollViewer.VerticalScrollBarVisibility="Visible" Content="{Binding Name}" Width="918" Height="48" Margin="0,12,0,98" Foreground="Black" Tapped="HyperlinkButton_Tapped_1" HorizontalContentAlignment="Left"/>
                <TextBlock FontSize="18" ScrollViewer.VerticalScrollBarVisibility="Visible" Text="{Binding Comment}" Width="884" Height="56" Margin="-930,59,0,43" Foreground="Black"/>
                <TextBlock ScrollViewer.VerticalScrollBarVisibility="Visible" Text="{Binding DateTime}" Width="583" Height="36" Margin="-1230, 90, 0,0" Foreground="Black"/>
                <TextBlock  ScrollViewer.VerticalScrollBarVisibility="Visible" Text="{Binding Votes}"  Margin="-500,100,0,10" Width="321" Height="48" Foreground="Black"/>
            </StackPanel>

        </DataTemplate>
    </ListView.ItemTemplate>
    <TextBlock Height="81" TextWrapping="Wrap" Text="TextBlock" Width="273"/>
</ListView>

我的按钮的 xaml.cs 代码

private async void btnVote_Click(object sender, RoutedEventArgs e)
{
    MyLearningStory.Clear(); 
    addVotes();
    retrieveLearningStory();


    //Service1Client updateclient = new Service1Client();
    //string update = await updateclient.updateVotesAsync(userId);

}

以及 getlearningstory() 的方法

public async void retrieveLearningStory()
{
    btnShowMore.IsEnabled = true;
    Service1Client retrieveClient = new Service1Client();

    if (firstRun == true)
    {
        if(userId!=""){/*
            learningStoryComment.AddRange(await retrieveClient.retrieveLearingStoryCommentAsync(userId, storyId));
            learningStoryDatetime.AddRange(await retrieveClient.retrieveLearingStoryDatetimeAsync(userId, storyId));
            learningStoryImg.AddRange(await retrieveClient.retrieveLearingStoryImgAsync(userId, storyId));
                        */
            learningStoryComment.AddRange(await retrieveClient.retrieveLearingStoryCommentByStoryIDAsync(storyId));
            learningStoryDatetime.AddRange(await retrieveClient.retrieveLearingStoryDateTimeByStoryIDAsync(storyId));
            learningStoryImg.AddRange(await retrieveClient.retrieveLearingStoryImgByStoryIDAsync(storyId));
            learningStoryUserId.AddRange(await retrieveClient.retrieveLearingStoryUserIDByStoryIDAsync(storyId));


            }
    }

    await Task.Delay(1000);

    string name = "";
    Service1Client client1 = new Service1Client();


    if(userId==null){
        userId = roamingSettings.Values["userID"].ToString();

    }

    if (firstRun == true)
    {
        initialValue = 0;
        firstRun = false;
        currentUserId = userId;

    }
    //finding the  author of the learningstory
    for (int a = initialValue; a < learningStoryComment.Count; a++)
    {

        if (a == (learningStoryComment.Count-1))
        {
            InMemoryRandomAccessStream randomAccessStream = new InMemoryRandomAccessStream();
            DataWriter writer = new DataWriter(randomAccessStream.GetOutputStreamAt(0));
            writer.WriteBytes(learningStoryImg[a]);
            await writer.StoreAsync();
            // Create bitmap image
            BitmapImage b = new BitmapImage();
            b.SetSource(randomAccessStream);

            name = await retrieveClient.retrieveNameByUserIDAsync(learningStoryUserId[0]);
           // status = await retrieveClient.RetrieveUserStatusAsync(learningStoryUserId[0]);

            imgFirstPost.Source = b;
            txtFirstPostComment.Text = learningStoryComment[a];
            txtFirstPostDateTime.Text = learningStoryDatetime[a].ToString();
            hbtnName.Content = name;
            hbtnName.Tag = currentUserId;

        }


    }

    //finding the other user that posted in the learningstory
    // for (int a = learningStoryComment.Count - 1; a > -1; a--)

    //tbvotesdisplay = count.ToString();
    for (int a = initialValue; a < learningStoryComment.Count; a++)
    {
        count++;
        InMemoryRandomAccessStream randomAccessStream = new InMemoryRandomAccessStream();
        DataWriter writer = new DataWriter(randomAccessStream.GetOutputStreamAt(0));
        writer.WriteBytes(learningStoryImg[a]);
        await writer.StoreAsync();
        // Create bitmap image
        BitmapImage b = new BitmapImage();
        b.SetSource(randomAccessStream);
        name = await client1.retrieveNameByUserIDAsync(learningStoryUserId[a]);
        //vote = await client1.retrieveVotesAsync(learningStoryUserId[a]);
        //status = await retrieveClient.RetrieveUserStatusAsync(learningStoryUserId[a]);

        if (a != (learningStoryComment.Count - 1))
        {
               MyLearningStory.Add(new LearningStoryItem(learningStoryComment[a], name, learningStoryDatetime[a], b, 1, userId, votescount));



        }
   lvLearningStory.DataContext = MyLearningStory;

我的加票方式

  public async void addVotes()
    {
        votescount++;
    }

我的 listview.datacontext 类

 public class LearningStoryItem
{
      public BitmapImage Img { get; set; }
    public string Comment{ get; set; }
   public DateTime DateTime { get; set; }
   public string Name {get; set;}
   public int StoryID { get; set; }
   public string UserID { get; set; }
   public string LastCommented { get; set; }
   public string View { get; set; }
   public double Votes { get; set; }

   public LearningStoryItem(double votes)
   {
       Votes = votes;
   }

    public LearningStoryItem(string comment, DateTime datetime, BitmapImage img)
    {
        Comment = comment;
        DateTime = datetime;
        Img = img;
        Votes = 200;
    }
    public LearningStoryItem(string comment)
    {
        Comment = comment;
    }
    public LearningStoryItem(int storyid)
    {
       StoryID = storyid;


    }

    public LearningStoryItem(string comment, string name, DateTime datetime, BitmapImage img)
    {
        Comment = comment;
        DateTime = datetime;
        Img = img;
        Name = name;

        Votes = 200;
    }
    public LearningStoryItem(string comment, string name, DateTime datetime, BitmapImage img, int storyid)
    {
        Comment = comment;
        DateTime = datetime;
        Img = img;
        Name = name;
        StoryID = storyid;

        Votes = 200;
    }
    public LearningStoryItem(string comment, string name, DateTime datetime, BitmapImage img, int storyid, string userid,double votes)
    {
        Comment = comment;
        DateTime = datetime;
        Img = img;
        Name = name;
        StoryID = storyid;
        UserID = userid;

        Votes = votes;

    }
    public LearningStoryItem(string comment, string name, DateTime datetime, BitmapImage img, int storyid, string userid,string lastCommented)
    {
        Comment = comment;
        DateTime = datetime;
        Img = img;
        Name = name;
        StoryID = storyid;
        UserID = userid;
        LastCommented = lastCommented;

        Votes = 200;
    }
    public LearningStoryItem(string comment, string name, DateTime datetime, BitmapImage img, int storyid, string userid, string lastCommented,string view)
    {
        Comment = comment;
        DateTime = datetime;
        Img = img;
        Name = name;
        StoryID = storyid;
        UserID = userid;
        LastCommented = lastCommented;
        View = view;

        Votes = 200;
    }

    public LearningStoryItem(DateTime datetime)
    {
        DateTime = datetime;

        Votes = 200;
    }
    public LearningStoryItem(BitmapImage img)
    {
        Img = img;

        Votes = 200;
    }
    public LearningStoryItem(int storyid,string userid)
    {
        StoryID = storyid;
        UserID = userid;

        Votes = 200;
    }

}

}

4

1 回答 1

1

您需要发送addVotes一些 id 以增加特定的投票值。如果我理解正确，你btnVote_Click现在增加所有选票。

编辑： 1）将 UserId 保存到Tag

 <Button x:Name="btnVote" BorderBrush="Black" Tag="{Binding UserID}"  BorderThickness="2" Height="45" Margin="0,70,0,43" Width="78" Content="Vote" Background="Black" Click="btnVote_Click" />

2）改变btnVote_Click

私人无效btnVote_Click（对象发送者，RoutedEventArgs e）{

        string userId = (string)(sender as Button).Tag;

         //getting `LearningStoryItem` by id from ListViewDataContext
        LearningStoryItem itemForRefresh = dataContext.Single(item => item.UserID == userId);
        //refresh only clicked item
        itemForRefresh.Votes = itemForRefresh.Votes+1;
        itemForRefresh.Comment = "new comment";

    }

3) 在中使用 DependencyPropertiesLearningStoryItem

public class LearningStoryItem:DependencyObject

private static DependencyProperty voteProperty;


    static LearningStoryItem()
    {
        var votePropertyMetadata = new FrameworkPropertyMetadata(Convert.ToDouble(0),
                                                                      FrameworkPropertyMetadataOptions.AffectsRender);
        voteProperty = DependencyProperty.Register("Votes",
                                                       typeof(double),
                                                       typeof(LearningStoryItem),
                                                       votePropertyMetadata);
    }

    public double Votes {
        get { return (double) GetValue(voteProperty); } 
        set {SetValue(voteProperty,value); }  
    }
于 2013-04-15T04:30:47.110 回答