XFC0045 绑定：在“EcoTracker.ViewModels.UserProfileViewModel”上找不到属性“标题”

Question

我使用 ViewModel 在个人资料页面上显示用户信息和帖子，但在尝试从 UserPosts 集合中获取这些帖子时出现错误 内容页.xaml：

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:viewModels="clr-namespace:EcoTracker.ViewModels"
             xmlns:converters="clr-namespace:EcoTracker.Converters" 
             x:DataType="viewModels:UserProfileViewModel"
             Title="Мой профиль"
             x:Class="EcoTracker.Views.UserProfilePage">
 <ContentPage.Content>
    <StackLayout>
       <Image Source="{Binding User.Avatar}" WidthRequest="100" HeightRequest="100" HorizontalOptions="Center" />
    </StackLayout>
<ListView x:Name="UserPostsListView" ItemsSource="{Binding UserPosts}" HasUnevenRows="True" VerticalOptions="FillAndExpand">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <Frame HasShadow="True" Margin="10" Padding="10" BackgroundColor="White" CornerRadius="15">
                    <StackLayout VerticalOptions="FillAndExpand">
                        <Label Text="{Binding Title}" FontAttributes="Bold" FontSize="16" />
                </Frame>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

ContentPage.xaml.cs：

public partial class UserProfilePage : ContentPage
{
    private readonly UserProfileViewModel viewModel;

    public UserProfilePage()
    {
        InitializeComponent();
        viewModel = new UserProfileViewModel();
        BindingContext = viewModel;
    }

    protected override async void OnAppearing()
    {
        base.OnAppearing();
        await viewModel.LoadUserDataAndPostsAsync();
    }
}

视图模型：

 public class UserProfileViewModel
 {
     private UserData _user;
     public UserData User
     {
         get { return _user; }
         set
         {
             _user = value;
             OnPropertyChanged(nameof(User));
         }
     }

     private ObservableCollection<UserPostModel> _userPosts;
     public ObservableCollection<UserPostModel> UserPosts
     {
         get { return _userPosts; }
         set
         {
             _userPosts = value;
             OnPropertyChanged(nameof(UserPosts));
         }
     }

     public event PropertyChangedEventHandler PropertyChanged;

     protected virtual void OnPropertyChanged(string propertyName)
     {
         PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
     }

     public async Task LoadUserDataAndPostsAsync()
     {
         User = UserDataHolder.GetUserData();
         int userId = User.Id;
         UserPosts = new ObservableCollection<UserPostModel>(await GetUserPostsAsync(userId));
         if (User == null)
         {
             User = new UserData();
         }

         int followersCount = await GetFollowersCountAsync(userId);
         if (followersCount >= 0)
         {
             User.FollowersCount = followersCount;
         }

         int followingCount = await GetFollowingCountAsync(userId);
         if (followingCount >= 0)
         {
             User.FollowingCount = followingCount;
         }
     }
}

我看到删除DataType的决定，然后错误消失了，但是页面上既没有显示用户数据也没有发布数据

Answer 1

您需要在模板中添加

DataType

<DataTemplate x:DataType="viewModels:UserPosts">

您可能还需要使用不同的

xmlns

，具体取决于您的代码结构