no command binding in checkbox

Question

hello, it is necessary that the checkbox click command parameter be this checkbox itself and it was possible in the viewModel to read the checkbox Uid. as much as possible simplified the code ...

<ListBox ItemsSource="{Binding Collection}"> <ListBox.ItemTemplate> <DataTemplate> <CheckBox Command="{Binding CheckBoxCommand}" CommandParameter="{Binding RelativeSource={RelativeSource Self}}" Uid="{Binding Element.Id}"/> <!--прибиндили к полю id поля Element из структуры из которых состоит Collection --> </DataTemplate> </ListBox.ItemTemplate> </ListBox>

RelayCommand:

 public class RelayCommand<T> : ICommand { private readonly Action<T> _execute; private readonly Predicate<T> _canExecute; public event EventHandler CanExecuteChanged; public RelayCommand(Action<T> execute) : this(execute, null) { } public RelayCommand(Action<T> execute, Predicate<T> canExecute) { if (execute == null) throw new ArgumentNullException("предикат не должен быть равным нулю"); _execute = execute; _canExecute = canExecute; } public bool CanExecute(object parameter) { return _canExecute == null ? true : _canExecute((T)parameter); } public void Execute(object parameter) { _execute((T)parameter); } public void RaiseCanExecuteChanged() { var handler = CanExecuteChanged; if (handler != null) { handler(this, EventArgs.Empty); } } }

viewModel:

 class ViewModel { /// <summary> /// команда щелчка по checkbox /// </summary> private ICommand checkBoxCommand = null; public ICommand CheckBoxCommand { get { if (checkBoxCommand == null) { checkBoxCommand = new RelayCommand<CheckBox>(AddData); } return checkBoxCommand; } } private void AddData(CheckBox o) { var df = ((CheckBox)o).Uid; int brackPoint = 0; } /// <summary> /// конструктор /// </summary> public ViewModel() { } public ObservableCollection<Element> Collection { /**/ }

}

Model (simplified):

 Struct Element { public ObservableCollection<someClass> Collection { /**/ } public int Id { /**/ }; }

I put a bryak in addData and click on checkBox - it does not go into addData, but there are no errors ... help solve the problem

Try this: Command="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBox}}, Path=DataContext.CheckBoxCommand}"
CommandParameter you sure that you need to transfer the CheckBox ?
Instead, it is better to send DataContext immediately: CommandParameter="{Binding}" , and then private void AddData(Element o) {var df = o.UId; int brackPoint = 0; }
private void AddData(Element o) {var df = o.UId; int brackPoint = 0; }
omg ... helped add code from AncestorType from the first post, thanks

Answer 1 · 2016-12-26T10:08:43

Bind to window context by name. You redefined the context when you specified an ItemSource.

 <Window x:Name="Main" ... <CheckBox Command="{Binding DataContext.CheckBoxCommand, ElementName=Main}"...

Council In order to preserve the isolation of the ViewModel from the View, I recommend passing in as the parameter not a CheckBox , but an Element

  <CheckBox Command="{Binding DataContext.CheckBoxCommand, ElementName=Main}" CommandParameter="{Binding}"...

ViewModel:

 checkBoxCommand = new RelayCommand<Element>(AddData); private void AddData(Element e) { var df = e.Id; ... }

in my case, the Uid cannot be in the properties of the viewModel. Because
The uid binds to the field of the structure of which the observablecollection consists, which, in turn, is attached to the listbox via the itemssource ... fixed the question condition taking into account the reality
@xperious well, so your binding goes to the elements of this structure.
And he is also looking for CheckBoxCommand there, and not in the ViewModel

no command binding in checkbox

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