c# - 转到 observablecollection 中的下一个对象时，窗口控件不更新

问题描述

我有一个我的测验问题类对象的 ObservableCollection。我有“下一步”按钮，并希望将窗口控件绑定到该集合中的特定问题对象。绑定似乎有效（最初正确填充了文本框），但是当我单击下一步时，它确实正确填充了我的 currQuestion 对象，文本框不会更新以显示当前问题，它会继续显示原始问题。我已经尽可能地剥离了 xaml 和代码隐藏，以使其更易于调试，是的，我知道我应该使用 mvvm，所以让我知道这是否是问题的一部分。这是我的xml

<Window x:Class="Quiz.QuizMaintWindow"
    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:Quiz"
    mc:Ignorable="d"
    Title="QuizMaintWindow" Height="450" Width="800" Loaded="Window_Loaded">
<Grid Name="grd1">
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="auto" MinWidth="100"/>
        <ColumnDefinition/>
        <ColumnDefinition/>
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition Height="auto"/>
        <RowDefinition Height="auto"/>
        <RowDefinition/>
    </Grid.RowDefinitions>
    <TextBox Name="txtQuestion" Grid.Column="0" Grid.Row="0" Text="{Binding Question}"/>
    <Button Name="btnNext" Grid.Column="0" Grid.Row="1" Content="Next" Margin="5" Click="btnNext_Click"/>
</Grid>

这是我的代码隐藏

    public partial class QuizMaintWindow : Window
{
    private clsQuestionAnswer qa;  // this is the current question to be displayed
    private ObservableCollection<clsQuestionAnswer> questions;
    private int questionIndex = 0;

    public QuizMaintWindow()
    {
        InitializeComponent();
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        GetTopicQuestions();
        grd1.DataContext = qa;
    }

    private void GetTopicQuestions()
    {
        questions = clsData.GetTopicQuestions(10);
        qa = questions[questionIndex];                             
    }

    private void btnNext_Click(object sender, RoutedEventArgs e)
    {
        qa = questions[++questionIndex];
        // MessageBox.Show(qa.Question);
    }
}

这是问题类

   public class clsQuestionAnswer: INotifyPropertyChanged
{
    private int questionId;
    private int topicId;
    private string question;
    private string answer;
    private bool ignore;

    public int QuestionId
    {
        get { return questionId; }
        set
        {
            questionId = value;
            NotifyPropertyChanged("QuestionId");
        }
    }

    public int TopicId
    {
        get { return topicId; }
        set
        {
            topicId = value;
            NotifyPropertyChanged("TopicId");
        }
    }

    public string Question
    {
        get { return question; }
        set
        {
            question = value;
            NotifyPropertyChanged("Question");
        }
    }

    public string Answer
    {
        get { return answer; }
        set
        {
            answer = value;
            NotifyPropertyChanged("Answer");
        }
    }

    public bool Ignore
    {
        get { return ignore; }
        set
        {
            ignore = value;
            NotifyPropertyChanged("Ignore");
        }            
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged(string info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }
}

标签： c#wpfobservablecollection

c# - 转到 observablecollection 中的下一个对象时，窗口控件不更新

问题描述

解决方案

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