mvvm

问题 I have some property which I am using from Page2 in HomePageViewModel, When I navigate to Page2 I have changed that property and on coming back by doing NavigiationPop. HomePage is not re-loaded/ refreshed at all as I have set the BindingContext in the constructor of HomePage, which is loaded only once. The solution which is working for me is Setting the BindingContext to the ViewModel on "onAppearing()", usually its not consider the best practice. But I also need to refresh the values which

问题 I made ViewModelFactory by this example: public class ViewModelFactory extends ViewModelProvider.NewInstanceFactory { @SuppressLint("StaticFieldLeak") private static volatile ViewModelFactory INSTANCE; private final Application application; public static ViewModelFactory getInstance(Application application) { if (INSTANCE == null) { synchronized (ViewModelFactory.class) { if (INSTANCE == null) { INSTANCE = new ViewModelFactory(application); } } } return INSTANCE; } private ViewModelFactory

问题 I have an ObservableCollection of 24 Things. private ObservableCollection<Thing> things; public ObservableCollection<Thing> Things { get => things; set { things= value; RaisePropertyChanged(); } } I also have a selected Thing private Thing selectedThing; public Thing SelectedThing { get => selectedThing; set { selectedThing= value; RaisePropertyChanged(); } } I need to display these items in a grid. I am creating a grid of buttons, each with a command and a command parameter that allows me to

问题 I'm trying to capture photo and display the captured image in Xamarin but changing the image source binding just doesn't seem to work. This seems really simple so I'm not quite sure where I'm going wrong. MainPageViewModel.cs public class MainPageViewModel : ViewModelBase { private string _imageSource; public string ImageSource { get { return _imageSource; } set { _imageSource = value; SetProperty(ref _imageSource, value); } } public DelegateCommand TakePhotoCommand { get; private set; }

问题 I am having some problems understanding xaml with mvvm. Sometimes works but others doesn't. ViewModel (implements INotifyPropertyChanged): private Class1 firstClass; public Class1 FirstClass{ get{return firstClass;} set{firstClass = value; OnPropertyChanged();} } private string name; public string Name{ get{return name;} set{name = value; OnPropertyChanged();} } private string address; public string Address{ get{return address;} set{address = value; OnPropertyChanged();} } View: private

问题 I develop a WPF application, obviously, I use MVVM pattern. Without an external library (MvvmCross, MvvmLight, ...) And I've tried to implement ICommand : Option 1 public class Command : ICommand { private readonly Func<bool> _canExecute; private readonly Action _action; public Command1(Action action, Func<bool> canExecute) { _action = action; _canExecute = canExecute; } public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager

问题 I got a problem with bindings(i know why am i becoming this exception but dunno how to solve the problem). I have tried this piece of code. <TextBlock HorizontalAlignment="Left" > <TextBlock.Margin> <Thickness Left="{Binding POSX.Value, Converter={StaticResource DPIConverter}}" Top="{Binding POSY.Value, Converter={StaticResource DPIConverter}}"/> </TextBlock.Margin> </TextBlock> Im getting an exception where it says that, u cant bind thickness [LEFT], [TOP] properties. (ik why : cause those

问题 Hello I have a repeating carousel I've copied for each deparment that I want to consolidate and make into a custom xaml view control. Here is the original carousel view I have copied several times in my page. I want to figure out how to clean this up with something externally from the page. <StackLayout Padding="10"> <Label Text="Human Resources" FontSize="Large" TextColor="#000000"></Label> <CarouselView ItemsSource="{Binding HumanResourcesCollection}" PeekAreaInsets="75" IndicatorView=

问题 I am learning android MVVM pattern android development. I wanted to create a recycclerview activity to show data from server. But it's not accepting my viewmodel class. Bellow is my logcat errors. LOGCAT 2020-04-12 21:03:18.026 2008-2008/com.shovon.mvvm E/AndroidRuntime: FATAL EXCEPTION: main Process: com.shovon.mvvm, PID: 2008 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.shovon.mvvm/com.shovon.mvvm.activity.RecyclerActivity}: java.lang.RuntimeException: Cannot

问题 I am learning android MVVM pattern android development. I wanted to create a recycclerview activity to show data from server. But it's not accepting my viewmodel class. Bellow is my logcat errors. LOGCAT 2020-04-12 21:03:18.026 2008-2008/com.shovon.mvvm E/AndroidRuntime: FATAL EXCEPTION: main Process: com.shovon.mvvm, PID: 2008 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.shovon.mvvm/com.shovon.mvvm.activity.RecyclerActivity}: java.lang.RuntimeException: Cannot