Xamarin.forms 如何在返回页面后取消选中复选框
我在视图模型中设置了一个复选框，我正在收集列表上的用户决定，但是一旦我筛选了我的项目，然后在页面上点击bakc，即使列表为空，复选框仍然处于选中状态，因此如果我再次按下按钮以显示筛选的项目，我将一无所获。我正在清理我的名单，但我不知道如何让复选框取消检查，一旦我回来。我有模式=双向Xamarin.forms 如何在返回页面后取消选中复选框,xamarin.forms,Xamarin.forms,我在视图模型中设置了一个复选框，我正在收集列表上的用户决定，但是一旦我筛选了我的项目，然后在页面上点击bakc，即使列表为空，复选框仍然处于选中状态，因此如果我再次按下按钮以显示筛选的项目，我将一无所获。我正在清理我的名单，但我不知道如何让复选框取消检查，一旦我回来。我有模式=双向 private bool _filterBeginnerItems = false; private bool _filterIntermediateItems = false; p
private bool _filterBeginnerItems = false;
private bool _filterIntermediateItems = false;
private bool _filterAdvancedItems = false;
private bool _filterUpperIntermediateItems = false;
public bool FilterBeginnerItems
{
set
{
NotifyPropertyChanged();
_filterBeginnerItems = value;
if (_filterBeginnerItems)
{
FilterAllItems = false;
UserDecision.Add(_parentCategoryId = 1);
}
}
get => _filterBeginnerItems;
}
public bool FilterIntermediateItems
{
set
{
NotifyPropertyChanged();
_filterIntermediateItems = value;
if (_filterIntermediateItems)
{
FilterAllItems = false;
UserDecision.Add(_parentCategoryId = 2);
}
}
get => _filterIntermediateItems;
}
public bool FilterUpperIntermediateItems
{
set
{
NotifyPropertyChanged();
_filterUpperIntermediateItems = value;
if (_filterUpperIntermediateItems)
{
FilterAllItems = false;
UserDecision.Add(_parentCategoryId = 3);
}
}
get => _filterUpperIntermediateItems;
}
public FilterArticlesForPurchaseViewModel(INavigation navigation)
: base()
{
Task.Run(async () => await LoadAllDataForArticlesAndCategories()).Wait();
FilterItemsCommand = new Command(async () => navigation.PushAsync(new ArticlesForPurchaseFiltered()));
UserDecision.Clear();
//FilterAdvancedItems = false;
// FilterBeginnerItems = false;
}
试图将其值设置为false，但没有帮助 我写了一个关于清除复选框的演示 这里是运行gif 下面是FilterArticlesForPurchaseViewModel.cs，用于实现INotifyPropertyChanged接口。我使用命令清除这些复选框
public class FilterArticlesForPurchaseViewModel: INotifyPropertyChanged
{
private bool _filterBeginnerItems = true;
private bool _filterIntermediateItems = false;
private bool _filterAdvancedItems = false;
private bool _filterUpperIntermediateItems = false;
public bool FilterBeginnerItems
{
set
{
// NotifyPropertyChanged();
_filterBeginnerItems = value;
OnPropertyChanged("FilterBeginnerItems");
//if (_filterBeginnerItems)
//{
// FilterAllItems = false;
// UserDecision.Add(_parentCategoryId = 1);
//}
}
get => _filterBeginnerItems;
}
public bool FilterIntermediateItems
{
set
{
// NotifyPropertyChanged();
_filterIntermediateItems = value;
OnPropertyChanged("FilterIntermediateItems");
//if (_filterIntermediateItems)
//{
// FilterAllItems = false;
// UserDecision.Add(_parentCategoryId = 2);
//}
}
get => _filterIntermediateItems;
}
public bool FilterUpperIntermediateItems
{
set
{
// NotifyPropertyChanged();
_filterUpperIntermediateItems = value;
OnPropertyChanged("FilterUpperIntermediateItems");
//if (_filterUpperIntermediateItems)
//{
// FilterAllItems = false;
// UserDecision.Add(_parentCategoryId = 3);
//}
}
get => _filterUpperIntermediateItems;
}
public ICommand ClearCommand { protected set; get; }
public FilterArticlesForPurchaseViewModel(INavigation navigation)
{
ClearCommand = new Command(async () =>
{
FilterBeginnerItems = false;
FilterIntermediateItems = false;
FilterUpperIntermediateItems = false;
});
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
}
<StackLayout>
<!-- Place new controls here -->
<CheckBox IsChecked="{Binding FilterBeginnerItems,Mode=TwoWay}"></CheckBox>
<CheckBox IsChecked="{Binding FilterIntermediateItems,Mode=TwoWay}"></CheckBox>
<CheckBox IsChecked="{Binding FilterUpperIntermediateItems,Mode=TwoWay}"></CheckBox>
<Button Text="clear" Command="{Binding ClearCommand}"></Button>
</StackLayout>
在导航到新页面之前，应清除并重置所有筛选器变量。我已尝试此操作//FilterAdvancedItems=false；//FilterBeginnerItems=false；但这并没有帮助我仍然设置了复选框为什么在设置属性值之前要调用NotifyPropertyChanged？注释不用于扩展讨论；这段对话已经结束。
public MainPage()
{
InitializeComponent();
this.BindingContext = new FilterArticlesForPurchaseViewModel(Navigation);
}
public class FilterViewModel : BaseViewModel
{
private bool _filterAllItems = true;
private bool _filterBeginnerItems = false;
private bool _filterIntermediateItems = false;
private bool _filterAdvancedItems = false;
private bool _filterUpperIntermediateItems = false;
private static List<Article> _allArticlesForPurchase;
private static List<Category> _allCategories;
private static List<CategoryGroup> _allUserCategoryGroups;
public static List<int> UserDecisionResult { get; set; }
private static int _parentCategoryId;
public ICommand FilterItemsCommand { get; private set; }
public static List<int> UserDecision { get; set; } = new List<int>();
public bool FilterAllItems
{
set
{
_filterAllItems = value;
OnPropertyChanged();
if (FilterAllItems == false)
{
if (UserDecision.Contains(_parentCategoryId = -1))
{
UserDecision.Remove(_parentCategoryId = -1);
}
}
if (FilterAllItems == true)
{
FilterBeginnerItems = false;
FilterIntermediateItems = false;
FilterUpperIntermediateItems = false;
FilterAdvancedItems = false;
if (!UserDecision.Contains(_parentCategoryId = -1))
{
UserDecision.Add(_parentCategoryId = -1);
}
if (UserDecision.Contains(_parentCategoryId=1))
{
UserDecision.Remove(_parentCategoryId = 1);
}
if (UserDecision.Contains(_parentCategoryId = 2))
{
UserDecision.Remove(_parentCategoryId = 2);
}
if (UserDecision.Contains(_parentCategoryId = 3))
{
UserDecision.Remove(_parentCategoryId = 3);
}
if (UserDecision.Contains(_parentCategoryId = 4))
{
UserDecision.Remove(_parentCategoryId = 4);
}
}
}
get => _filterAllItems;
}
public bool FilterBeginnerItems
{
set
{
_filterBeginnerItems = value;
OnPropertyChanged();
if (_filterBeginnerItems)
{
FilterAllItems = false;
UserDecision.Add(_parentCategoryId = 1);
if (UserDecision.Contains(_parentCategoryId = -1))
{
UserDecision.Remove(_parentCategoryId = -1);
}
}
}
get => _filterBeginnerItems;
}
public bool FilterIntermediateItems
{
set
{
_filterIntermediateItems = value;
OnPropertyChanged();
if (_filterIntermediateItems)
{
FilterAllItems = false;
UserDecision.Add(_parentCategoryId = 2);
if (UserDecision.Contains(_parentCategoryId = -1))
{
UserDecision.Remove(_parentCategoryId = -1);
}
}
}
get => _filterIntermediateItems;
}
public bool FilterUpperIntermediateItems
{
set
{
_filterUpperIntermediateItems = value;
OnPropertyChanged();
if (_filterUpperIntermediateItems)
{
FilterAllItems = false;
UserDecision.Add(_parentCategoryId = 3);
if (UserDecision.Contains(_parentCategoryId = -1))
{
UserDecision.Remove(_parentCategoryId = -1);
}
}
}
get => _filterUpperIntermediateItems;
}
public bool FilterAdvancedItems
{
set
{
_filterAdvancedItems = value;
OnPropertyChanged();
if (_filterAdvancedItems)
{
FilterAllItems = false;
UserDecision.Add(_parentCategoryId = 4);
if (UserDecision.Contains(_parentCategoryId = -1))
{
UserDecision.Remove(_parentCategoryId = -1);
}
}
}
get => _filterAdvancedItems;
}
public FilterViewModel()
{
FilterItemsCommand = new Command(async () => await FilterItems());
FindAllArticlesForPurchase();
}
public ObservableCollection<Article> FilterArticlesForPurchase { get; } = new ObservableCollection<Article>();
private static void FindAllArticlesForPurchase()
{
foreach (var userDecision in UserDecision)
{
if (userDecision != -1)
{
if (UserDecision.Count > 1)
{
Console.WriteLine("more than one item");
}
else
{
Console.WriteLine("one item");
}
}
else
{
Console.WriteLine("not minus one");
}
}
}
private async Task FilterItems()
{
await Application.Current.MainPage.Navigation.PushAsync(new Filter());
}
}
public partial class MainPage : ContentPage
{
public static FilterViewModel filterViewModel ;
public MainPage()
{
InitializeComponent();
filterViewModel= new FilterViewModel();
BindingContext = filterViewModel;
}
}
public partial class Filter: ContentPage
{
public Filter()
{
InitializeComponent();
BindingContext = MainPage.filterViewModel;
//If this FilterAllItems is empty, you want AllItems the checkbox to unselect, just set the value to false, the checkbox will update in the MainPage
MainPage.filterViewModel.FilterAllItems = false;
}
}