根據 ComboBox 選擇填充 WPF 列表框

Question

我正在嘗試使用基於 ComboBox 選擇的 SQL 存儲過程中的數據填充 WPF 列表框。 我已經讓 ComboBox 按預期工作，但我無法讓 ListBox 顯示任何數據。 我的命名可能有點奇怪，但可以將其想象為：ComboBox 從 SQL 獲取所有食譜，並且 ListBox 需要根據用戶從中選擇 ZFD249A0C28275EBF5CFZC4C 顯示成分列表及其數量。 The API and Stored Procedures(...GetAll() for the ComboBox and GetByRationId() for the ListBox...) work, as I can retrieve the correct data using Swagger in the API and I can Populate the ComboBox and the RationId TextBlock在 UI 中，但我無法讓 ListBox 顯示任何數據。 我對編程還是新手，我正在學習教程等，我似乎找不到任何特別適合我的情況的東西。 我猜我錯過了一些東西。 我添加了前面提到的 TextBlock 只是為了顯示 RationId，這是從 SQL 獲取正確數據所需要的，作為測試，只是為了確保 Id 正在通過……它是。

這是 Xaml...

    <StackPanel Grid.Column="1" Margin="50" Orientation="Vertical">
        <ComboBox x:Name="FeedGroup" MinWidth="300" MinHeight="50"
                  SelectedItem="{Binding SelectedFeedGroup}">
            <ComboBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding FeedGroupName}" />
                </DataTemplate>
            </ComboBox.ItemTemplate>
        </ComboBox>
        
        <TextBlock x:Name="SelectedFeedGroup_RationId" Height="81"/>

        <ListBox x:Name="FeedGroupRation" MinHeight="200" Padding="20" ItemsSource="{Binding SelectedFeedGroupRation}">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal" Margin="10" HorizontalAlignment="Center">
                        <TextBlock Text="{Binding CommodityName}" FontSize="20" FontWeight="Bold"
                            VerticalAlignment="Center" HorizontalAlignment="Center"/>
                        <TextBlock Text="{Binding CommodityPercentage}" FontSize="16" VerticalAlignment="Center"/>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox> 
    </StackPanel>

這是 ViewModel Class...

public class FeedGroupPageViewModel : Screen
{

    IFeedGroupEndPoint _feedGroupEndPoint;
    IFeedGroupRationEndPoint _feedGroupRationEndPoint;
    IMapper _mapper;
    private readonly StatusInfoViewModel _status;
    private readonly IWindowManager _window;


    public FeedGroupPageViewModel(IFeedGroupEndPoint feedGroupEndPoint,
            IFeedGroupRationEndPoint feedGroupRationEndpoint,
            IConfigHelper configHelper,
            IMapper mapper,
            StatusInfoViewModel status,
            IWindowManager window)
    {
        _feedGroupEndPoint = feedGroupEndPoint;
        _feedGroupRationEndPoint = feedGroupRationEndpoint;
        _configHelper = configHelper;
        _mapper = mapper;
        _status = status;
        _window = window;
    }

    protected override async void OnViewLoaded(object view)
    {
        base.OnViewLoaded(view);
        try
        {
            await LoadFeedGroup();
        }
        catch (Exception ex)
        {

        }
    }

    private async Task LoadFeedGroup()
    {
        var FeedGroupList = await _feedGroupEndPoint.GetAll();
        var feedGroup = _mapper.Map<List<FeedGroupDisplayModel>>(FeedGroupList);
        FeedGroup = new BindableCollection<FeedGroupDisplayModel>(feedGroup);
    }

    private BindableCollection<FeedGroupDisplayModel> _feedGroup;
    public BindableCollection<FeedGroupDisplayModel> FeedGroup
    {
        get { return _feedGroup; }
        set
        {
            _feedGroup = value;
            NotifyOfPropertyChange(() => FeedGroup);
        }
    }

    private FeedGroupDisplayModel _selectedFeedGroup;
    public FeedGroupDisplayModel SelectedFeedGroup
    {
        get { return _selectedFeedGroup; }
        set
        {
            _selectedFeedGroup = value;
            NotifyOfPropertyChange(() => SelectedFeedGroup);
        }
    }



    private BindableCollection<FeedGroupRationModel> _feedGroupRation;
    public BindableCollection<FeedGroupRationModel> FeedGroupRation
    {
        get { return _feedGroupRation; }

        set
        {
            _feedGroupRation = value;
            NotifyOfPropertyChange(() => FeedGroupRation);
        }
    }

    private BindableCollection<FeedGroupRationModel> _selectedFeedGroupRation;
    public BindableCollection<FeedGroupRationModel> SelectedFeedGroupRation
    {
        get { return _selectedFeedGroupRation; }
        set
        {
            _selectedFeedGroupRation = value;
            NotifyOfPropertyChange(() => SelectedFeedGroupRation);
        }
    }
}

這里是 Model 類

public class FeedGroupDisplayModel : INotifyPropertyChanged
{
    public int Id { get; set; }
    public string UserId { get; set; }
    public string FeedGroupName { get; set; }
    public DateTime CreateDate { get; set; }
    public DateTime LastModified { get; set; }
    public int RationId { get; set; }



    public event PropertyChangedEventHandler PropertyChanged;
    public void CallPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}


public class FeedGroupRationModel : INotifyPropertyChanged
{
    public int Id { get; set; }
    public string UserId { get; set; }
    public int RationId { get; set; }
    public string RationName { get; set; }
    public int CommodityId { get; set; }
    public string CommodityName { get; set; }
    public int CommodityPercentage { get; set; }



    public event PropertyChangedEventHandler PropertyChanged;
    public void CallPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

這是我的端點類

public class FeedGroupEndPoint : IFeedGroupEndPoint
{
    private IAPIHelper _apiHelper;

    public FeedGroupEndPoint(IAPIHelper apiHelper)
    {
        _apiHelper = apiHelper;
    }

    public async Task<List<FeedGroupModel>> GetAll()
    {
        using (HttpResponseMessage response = await _apiHelper.ApiClient.GetAsync("/api/FeedGroup"))
        {
            if (response.IsSuccessStatusCode)
            {
                var result = await response.Content.ReadAsAsync<List<FeedGroupModel>>();
                return result;
            }
            else
            {
                throw new Exception(response.ReasonPhrase);
            }
        }
    }
}

和

public class FeedGroupRationEndPoint : IFeedGroupRationEndPoint
{
    private IAPIHelper _apiHelper;

    public FeedGroupRationEndPoint(IAPIHelper apiHelper)
    {
        _apiHelper = apiHelper;
    }
    public async Task<List<FeedGroupRationModel>> GetRationById()
    {
        using (HttpResponseMessage response = await _apiHelper.ApiClient.GetAsync("/api/FeedGroup"))
        {
            if (response.IsSuccessStatusCode)
            {
                var result = await response.Content.ReadAsAsync<List<FeedGroupRationModel>>();
                return result;
            }
            else
            {
                throw new Exception(response.ReasonPhrase);
            }
        }
    }
}

如果需要，我可以添加更多信息。 我已經為此工作了很長一段時間，但我只是沒有想法。 任何幫助將不勝感激！ 提前致謝！！

Answer 1

您似乎沒有設置ListBox綁定到某處的FeedGroupRation 。

我猜你想在設置SelectedFeedGroup屬性時獲取項目並設置屬性。 然后，您可以將事件處理程序連接到PropertyChanged事件或覆蓋NotifyOfPropertyChange方法。 像這樣的東西：

public override async void NotifyOfPropertyChange([CallerMemberName] string propertyName = null)
{
    base.NotifyOfPropertyChange(propertyName);
    if (propertyName == nameof(FeedGroup))
    {
        //get the items...
        var results = await ...;
        //set the source property
        FeedGroupRation = results;
    }

}

Answer 2

正如@Michal Davis 評論所說，我缺少一種加載口糧的方法，所以我添加了 LoadFeedGroupRation()...

    private async Task LoadFeedGroupRation()
    {
        var _feedGroupRation = await _feedGroupRationEndPoint.GetRation();
        var feedGroupRation = _mapper.Map<List<FeedGroupRationDisplayModel>> 
        (_feedGroupPenList);
        FeedGroupRationList = new BindableCollection<FeedGroupRationDisplayModel> 
        (feedGroupRation);
    }

同樣基於@EldHasp 的評論，我更新了 SelectedFeedGroup 設置器...

public FeedGroupDisplayModel SelectedFeedGroup
{
    get { return _selectedFeedGroup; }
    set
    {
        _selectedFeedGroup = value;
        var FeedGroupRation = LoadFeedGroup
        NotifyOfPropertyChange(() => SelectedFeedGroup);
    }
}

我不知道這是否是最好的方法，但我為我的案子工作。