Xamarin.forms 不显示Cosmos数据库中的项目

我的显示方法有问题。我一直在学习xamarin的MSToDo项目教程。 我能够插入到数据库中，所以我知道它可以工作，但无法从数据库中获取任何信息。你能帮我吗

这是我的获取方法

static DocumentClient docClient = null;

        static readonly string databaseName = "xxxxx";
        static readonly string collectionName = "xxxxx";
        static bool Initialize() //connection
        {
            if (docClient != null)
                return true;

            try
            {
                docClient = new DocumentClient(new Uri(AppConstants.CosmosEndpointUrl), AppConstants.CosmosAuthKey);


            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex);


                docClient = null;

                return false;
            }

            return true;

        }

         public async static Task<List<Post>> GetPosts()
                {
                    var posts = new List<Post>();

                    if (! Initialize())
                        return posts;

                    var postQuery = docClient.CreateDocumentQuery<Post>(
                        UriFactory.CreateDocumentCollectionUri(databaseName, collectionName),
                         new FeedOptions { MaxItemCount = 1, EnableCrossPartitionQuery = true })
                        .OrderBy(i => i.Date)
                        .AsDocumentQuery();

                    while (postQuery.HasMoreResults)
                    {
                        var queryResults = await postQuery.ExecuteNextAsync<Post>();

                        posts.AddRange(queryResults);
                    }

                    return posts;
                }
    public class PostViewModel : BaseViewModel
        {
            List<Post> posts;

            public PostViewModel()
            {
                Posts = new List<Post>();
                RefreshCommand = new Command(async () => await ExecuteRefreshCommand());

            }
            private PostViewModel _selectedAd;
            //private ObservableCollection<Post> _posts;
            public List<Post> Posts { get => posts; set { posts = value; OnPropertyChanged(); } }

            public ICommand RefreshCommand { get; }
      async Task ExecuteRefreshCommand()
            {
                if (IsBusy) return;

                IsBusy = true;

                try
                {
                    Posts = await AdService.GetPosts();
                }
                finally
                {
                    IsBusy = false;
                }
            }

还有我的xaml

 <ListView  
                        ItemsSource="{Binding Posts}" x:Name="AdLogListView"
                            ItemTemplate="{StaticResource HomePageTemplate}"
                            SelectionMode="Single" Margin="12,0">

---

绑定源路径应该是Post而不是Post。您修改的xaml将是：-

 <ListView  
                        ItemsSource="{Binding Posts}" x:Name="AdLogListView"
                            ItemTemplate="{StaticResource HomePageTemplate}"
                            SelectionMode="Single" Margin="12,0">

是的，刚刚添加了，我得到System.InvalidCastException:'指定的强制转换无效。'PostViewModel PostViewModel//专用SQLite连接_conn；公共主页（）{InitializeComponent（）；postViewModel=new postViewModel（）；BindingContext=postViewModel；}受保护的覆盖void OnAppearing（）{base.OnAppearing（）；postViewModel.RefreshCommand.Execute（null）；}没有发生什么事，但现在它起作用了。。这我要归功于你好的，谢谢你！让我知道进一步的疑问。

 <ListView  
                        ItemsSource="{Binding Posts}" x:Name="AdLogListView"
                            ItemTemplate="{StaticResource HomePageTemplate}"
                            SelectionMode="Single" Margin="12,0">