如何以Xamarin形式实现Expandable ListView

Question

我正在使用服务从json获取一些值。 我将它们显示在主页（IrrigNetPage）上，其中有三个标签，因此我想在每个标签上以不同的方式对它们进行排序。

这是我的模特：

a) ObjectMapper mapper = new ObjectMapper();
b) mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
c) mapper.writeValueAsString(EmployeeListobjects);

这是View中xaml代码的一部分：

public class IrrigNetModel
{
    public IrrigNetModelItem[] items { get; set; }
}

public class IrrigNetModelItem
{
    public int ID { get; set; }
    public string Message { get; set; }
    public DateTime Date { get; set; }
    public string DateText { get; set; }
    public int StationId { get; set; }
    public string StationName { get; set; }
    public float StationLongitude { get; set; }
    public float StationLatitude { get; set; }
    public int ServiceId { get; set; }
    public string ServiceName { get; set; }
}

当然，这是ViewModel的一部分：

        <StackLayout
            Grid.Column="1"
            Orientation="Horizontal"
            HorizontalOptions="FillAndExpand"
            BackgroundColor="{Binding LocationTabColor}"
            Padding="10"
            Margin="1">
            <StackLayout.GestureRecognizers>
                <TapGestureRecognizer Command="{Binding TabTappedCommand}" CommandParameter="location"/>
            </StackLayout.GestureRecognizers>
            <Image Source="{Binding LocationTabIcon}"
                   HorizontalOptions="Start"
                   VerticalOptions="Center" 
                   WidthRequest="16"
                   HeightRequest="16"
                   Aspect="AspectFit"
                   x:Name="LocationIcon"/>
            <Label Text="{i18n:Translate Location}"
                   VerticalOptions="FillAndExpand" 
                   HorizontalOptions="FillAndExpand"
                   VerticalTextAlignment="Center"
                   HorizontalTextAlignment="Start"
                   TextColor="{Binding LocationTabTextColor}"/>
        </StackLayout>

在其中设置一些比例值的地方，如您在此处看到的，我将方法称为GroupServicesByLocation（）;。看起来像这样：

        else if (tabName == "location")
        {
            ServiceTabColor = Color.FromHex("#f4f4f4");
            LocationTabColor = Colors.MENU_SELECTED_ITEM;
            MapTabColor = Color.FromHex("#f4f4f4");

            ServiceTabIcon = "services.png";
            LocationTabIcon = "location_sel.png";
            MapTabIcon = "location.png";

            ServiceTabTextColor = Colors.MENU_SELECTED_ITEM;
            LocationTabTextColor = Color.FromHex("#ffffff");
            MapTabTextColor = Colors.MENU_SELECTED_ITEM;

            ListHederIcon = "location.png";

            IsListVisible = IsListVisible;
            IsGridHeaderVisible = true;
            IsMapVisible = false;

            if (ServiceName == "irrigNET")
            {
                FrameIcon = "service_irrig.png";
            }
            else
            {
                FrameIcon = "service_trap.png";
            }
            GroupServicesByLocation();
        }