ObservableCollection 不要在 CodeBehind 中绑定

Question

ObservableCollection 不绑定大家好，

我在 Xamarin Forms 中使用 ObservableCollection 的一个问题上需要帮助。我需要构建一个 "Custom ListView" 以使 TabIndex 在我的屏幕上正常工作。为此，我在后面的代码中创建： - 滚动视图 - 标签 - 条目

屏幕渲染正常，唯一的问题是在一个 ObservableCollection 中绑定。

我测试了一个属性使用 OnPropertyChanged 的单个字符串工作正常，但使用 ObservableCollection 不工作。我尝试使用 CollectionChanged 但没有成功。

有人遇到同样的问题吗？存在解决方案吗？

ViewModel:

    private ObservableCollection<RawData> rawDataList;
    public ObservableCollection<RawData> RawDataList
    {
        get { return rawDataList; }
        set { rawDataList = value; OnPropertyChanged("RawDataList"); }
    }

代码隐藏

    private void BuildRawDataTemplate()
    {
        var grid = BuildGrid();

        #region Templates
        grid.Children.Add(BuildScheduleHeaderTitleTemplate(), 0, 0); // Posição: Coluna: 0 | Linha: 0
        grid.Children.Add(BuildScheduleDetailsSubtitleTemplate("Dados Brutos"), 0, 1); // Posição: Coluna: 0 | Linha: 1
        #endregion

        #region RawData
        var scrollView = BuildScrollView();
        var stackLayout = BuildStackLayout("DefaultLight", 10, StackOrientation.Vertical, null, LayoutOptions.Center);

        rawDataCount = scheduleViewModel.RawDataList.Count();
        foreach (var item in scheduleViewModel.RawDataList.Select((rawData, i) => new { i, rawData }))
        {
            stackLayout.Children.Add(GenerateLabel(item.rawData.Identification));

            if (item.rawData.InfoTypeId == (int)InfoType.Equipment)
                stackLayout.Children.Add(GenerateEquipmentsPicker(item.rawData, item.i, item.i == 0, rawDataCount == (item.i + 1)));
            else
                stackLayout.Children.Add(GenerateEntry(item.rawData, item.i, item.i == 0, rawDataCount == (item.i + 1)));
        }
        scrollView.Content = stackLayout;

        grid.Children.Add(scrollView, 0, 2); // Posição: Coluna: 0 | Linha: 2
        #endregion

        #region Buttons
        var stackLayoutFooterButtons = BuildStackLayout(string.Empty, null, StackOrientation.Horizontal, LayoutOptions.End, null);
        stackLayoutFooterButtons.Children.Add(GeneratePrimaryButton("RESULTADOS", scheduleViewModel.VisibleResultCommand, rawDataCount++, scheduleViewModel.SelectedSampleBase.Finished));
        stackLayoutFooterButtons.Children.Add(GeneratePrimaryButton("CALCULAR", scheduleViewModel.CalculateRawDataCommand, rawDataCount++, !scheduleViewModel.SelectedSampleBase.Synced));
        stackLayoutFooterButtons.Children.Add(GeneratePrimaryButton("SALVAR", scheduleViewModel.SaveRawDataCommand, rawDataCount++, !scheduleViewModel.SelectedSampleBase.Synced));

        grid.Children.Add(stackLayoutFooterButtons, 0, 3); // Posição: Coluna: 0 | Linha: 3
        #endregion

        Content = grid;

        SetFocusOnFirstEntry();
    }

    private Entry GenerateEntry(RawData rawData, int tabIndex, bool firstElement = false, bool hasNextTabIndex = false)
    {
        var entry = new Entry();
        entry.TabIndex = tabIndex;

        entry.Text = rawData.DisplayValue;
        entry.SetBinding(Entry.TextProperty, nameof(rawData.DisplayValue), BindingMode.TwoWay);

        entry.StyleId = $"RawDataDynamicEntry_{tabIndex}";
        entry.IsTabStop = true;
        entry.IsEnabled = rawData.NotSynced;

        if (rawData.InfoTypeId == (int)InfoType.Integer)
            entry.Behaviors.Add(new NumericValidationBehavior());

        if (firstElement)
            entry.Focus();

        // Temp
        var focusOnReturnBehavior = new FocusOnReturnBehavior();
        focusOnReturnBehavior.HasNextTabIndex = hasNextTabIndex;
        entry.Behaviors.Add(focusOnReturnBehavior);

        return entry;
    }

Answer 1

我对这个问题有点困惑。但我相信您在将条目添加到列表视图时遇到问题。您的 Observable 集合数据未填充到 Listview 中。

我写了一篇关于创建多选列表视图的 post。您只看到我如何创建列表视图并将可观察集合的内容绑定到它。

请看这里：https://androidwithashray.blogspot.com/2018/03/multiselect-list-view-using-xamarin.html

请注意，对于列表视图，如果内容更适合屏幕，则不需要滚动视图，因为列表视图会自动滚动。

希望对您有所帮助！！

Answer 2

为了解决我的问题，我使用：

代码隐藏

    #region Events Changed
    private void EntryTextChanged(object sender, TextChangedEventArgs e)
    {
        var entryChanged = (Entry)sender;
        selectedRawData.DisplayValue = entryChanged.Text;
    }
    private void PickerSelectedIndexChanged(object sender, System.EventArgs e)
    {
        var pickerChanged = (Picker)sender;
        selectedRawData.DisplayValue = selectedItem.Identification;
    }
    #endregion

ObservableCollection 不要在 CodeBehind 中绑定

ObservableCollection don't Binding in CodeBehind

xamarin

xamarin.forms

xamarin.uwp