C# (Xamarin) - 如何从 "ObservableCollection<T>" 访问对象属性？

Question

我有这个功能可以创建一个 ObservableCollection<MenuBody> 来创建我的 Xamarin.Forms 用户菜单。

    private ObservableCollection<MenuBody> _userList;
    public ObservableCollection<MenuBody> UserList
    {
        set { SetProperty(ref _userList, value); }
        get { return _userList; }
    }

    private void LoadUserMenu()
    {
        UserList = new ObservableCollection<MenuBody>
        {
            new MenuBody
            {   
                Id = 1,
                Text = "Principal",
                Icon = IconFont.FileSignature,
            },
            new MenuBody
            {
                Id = 2,
                Text = "Configurações",
                Icon = IconFont.Cog,
            },
        };
    }

XAML CollectionView 绑定属性：

<CollectionView 
    x:Name="MyUserCollectionView"
    BackgroundColor="Transparent" 
    ItemsSource="{Binding UserList}"
    SelectionMode="Single"
    SelectionChangedCommand="{Binding MenuUserTappedCommand}" 
    SelectionChangedCommandParameter="{Binding SelectedItem, 
                                       Source{x:ReferenceMyUserCollectionView}}"

我用来检测用户点击菜单的函数。

     private DelegateCommand<object> _menuUserTappedCommand;

     public DelegateCommand<object> MenuUserTappedCommand =>
    _menuUserTappedCommand ?? (_menuUserTappedCommand = new DelegateCommand<object>(ExecuteMenuUserTappedCommand));

async void ExecuteMenuUserTappedCommand(object parameter)
{
    await App.Current.MainPage.DisplayAlert("Message", "Item " + parameter + " clicked", "Ok");
}

我正在尝试从此处访问 MenuBody Id 属性：

我试图写成 parameter.Id 来引用它，但它没有按预期出现。

谁能帮我找出我错在哪里？

Answer 1

要么施放它

var item = (MenuBody)parameter;
// then you can use item.Id

或使用正确的类型而不是对象

public DelegateCommand<MenuBody> MenuUserTappedCommand =>
_menuUserTappedCommand ?? (_menuUserTappedCommand = new DelegateCommand<MenuBody>(ExecuteMenuUserTappedCommand));

async void ExecuteMenuUserTappedCommand(MenuBody parameter)
{
    await App.Current.MainPage.DisplayAlert("Message", "Item " + parameter.Id + " clicked", "Ok");
}

C# (Xamarin) - 如何从 "ObservableCollection<T>" 访问对象属性？

C# (Xamarin) - How to access an object attribute from an "ObservableCollection<T>"?

c#

xaml

xamarin.forms

observablecollection