Question

窗口不会更新。首次启动时，它将显示正确的数据。但是，当数据更改时，窗口将不会更新。我以这种方式进行了其他一些课程，它们可以正常工作。

XAML类：

<Window x:Class="Kwisspel.View.PlayWindow"
    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:Kwisspel.View"
    mc:Ignorable="d"
    Title="PlayWindow" Height="450" Width="800"
    DataContext="{Binding Play, Source={StaticResource Locator}}">
<Grid>
    <TextBlock HorizontalAlignment="Left" Margin="57,34,0,0" TextWrapping="Wrap" Text="{Binding CurrentQuestion.Text, Mode=TwoWay}" VerticalAlignment="Top" Height="43" Width="649"/>
    <ComboBox ItemsSource="{Binding CurrentQuestionAnswers}" SelectedItem="{Binding SelectedAnswer, Mode =TwoWay}" HorizontalAlignment="Left" Margin="230,239,0,0" VerticalAlignment="Top" Width="120"/>
    <Button Content="Bevestig&#xD;&#xA;" Command="{Binding ConfirmAnswer}" HorizontalAlignment="Left" Margin="522,270,0,0" VerticalAlignment="Top" Width="111" Height="46"/>


</Grid>

C＃类：

public class PlayViewModel
{
    public QuizViewModel CurrentQuiz { get; set; }
    public QuestionViewModel CurrentQuestion { get; set; }
    public QuestionViewModel[] CurrentQuizQuestions { get; set; }
    public ObservableCollection<String> CurrentQuestionAnswers { get; set; }
    public AnswerViewModel SelectedAnswer { get; set; }
    public ICommand ConfirmAnswer { get; set; }
    private int _Counter;
    public int CorrectAnswers { get; set; }
    public PlayWindow p;

 public PlayViewModel(QuizViewModel currentQuiz)
    {
        _Counter = 0;
        this.ConfirmAnswer = new RelayCommand(_ConfirmAnswer);
        this.CurrentQuiz = currentQuiz;
        this.CurrentQuizQuestions = CurrentQuiz.Questions.ToArray();
        CurrentQuestion = CurrentQuizQuestions[_Counter];
        CurrentQuestionAnswers = new ObservableCollection<string>(CurrentQuestion.Answers.Select(a => a.Answer.ToString()));
    }

    private void _ConfirmAnswer()
    {

        _Counter++;
        CurrentQuestion = CurrentQuizQuestions[_Counter];
        CurrentQuestionAnswers = new ObservableCollection<string>(CurrentQuestion.Answers.Select(a => a.Answer.ToString()));
    }
}

Answer 1

更改属性后，您的属性需要引发PropertyChanged事件。您的课程应实现INotifyPropertyChanged

/// <inheritdoc cref="INotifyPropertyChanged"/>
public partial class YourViewModel : INotifyPropertyChanged
{
    /// <inheritdoc/>
    public event PropertyChangedEventHandler PropertyChanged;

    /// <summary>
    /// Notifies that a properties value has changed.
    /// </summary>
    /// <param name="propertyName">The property that has changed.</param>
    public virtual void NotifyPropertyChanged([CallerMemberName]string propertyName = null)
    {
        this.CheckForPropertyErrors();

        this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

，然后您的属性应如下所示：

    private QuestionViewModel currentQuestion;
    public QuestionViewModel CurrentQuestion
    {
        get
        {
            return this.currentQuestion;
        }

        set
        {
            this.currentQuestion = value;
            this.NotifyPropertyChanged();
        }
    }

WPF绑定正确，但是窗口不更新

1 个答案: