Question

我有viewmodel（使用Fody INPC）：

public sealed class ItemsViewModel : MvxViewModel, IMvxNotifyPropertyChanged
{
    private readonly IItemsService itemsService;

    public MvxObservableCollection<Item> ItemsCollection { get; private set; }
    public IMvxCommand GetItemsCommand { get; private set; }

    private async void GetItemsAsync()
    {
        var items = await itemsService.GetItemsAsync();
        ItemsCollection.Clear();
        ItemsCollection.AddRange(items);
    }

    public ItemsViewModel(IItemsService itemsService)
    {
        this.itemsService = itemsService;
        ItemsCollection = new MvxObservableCollection<Item>();
        GetItemsCommand = new MvxCommand(() => GetItemsAsync());
    }
}

AddRange（items）工作正常。稍后，我为此viewmodel添加了视图：

<views:MvxWpfView x:Class="MyApp.ItemsView"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:views="clr-namespace:MvvmCross.Platforms.Wpf.Views;assembly=MvvmCross.Platforms.Wpf">

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition/>
    </Grid.RowDefinitions>

    <Button Content="Get Items" Command="{Binding GetItemsCommand}"/>

    <ListView Grid.Row="1" ItemsSource="{Binding ItemsCollection}"/>
</Grid>

它背后的代码：

[MvxViewFor(typeof(ItemsViewModel))]
partial class ItemsView
{
    public DocumentTypeEditorView()
    {
        InitializeComponent();
    }
}

现在，当我点击按钮时，我收到错误“不支持范围操作”。当我从xaml中删除ListView时，一切正常。我可以将ListView更改为DataGrid或其他列表控件 - 错误将是相同的！

我想知道，如何将我的视图绑定到MvxObservableCollection？

Answer 1

如果您自己逐个将项目添加到源集合中，该怎么办？：

private async void GetItemsAsync()
{
    var items = await itemsService.GetItemsAsync();
    ItemsCollection.Clear();
    foreach (var item in items)
        ItemsCollection.Add(item);
}

...或者将source属性重新设置为新集合：

private async void GetItemsAsync()
{
    var items = await itemsService.GetItemsAsync();
    ItemsCollection = new MvxObservableCollection<Item>(items);
}

显然＆＃34;不支持范围操作＆＃34;对于数据绑定MvxObservableCollection。

MvxObservableCollection AddRange

1 个答案: