I have a list of States in an ItemsControl, the DataTemplate is a CheckBox. I would like to add a function to select(check) all states. However I need to loop through the CheckBoxs rather then the data items since the checked state is stored in a separate data structure then the list of states the ItemsControl's ItemSource is bound to.
Have a property in your DataObject called IsChecked and bind that to the Checkbox in DataTemplate(Default is TwoWay)
In the data template I subscribed to the checkbox's onload event. And in the event handler I add the checkbox reference to a generic list of checkbox.
Related
if check box is checked, tree view should be created and populated.
On un checking the checkbox,it it should be hidden
If you follow MVVM
then you can have a style set on Checkbox ischecked to control visibility of your tree or you can set a visibility converter on binding of checkbox.
then you should bind your checkbox to a viewmodel property, when that value is set, you should populate your itemsList that is bound to your tree control
let me know if you do not understand any part !
I have a WPF View where I create controls dynamically depending on the object type in a List that the View is bound to in the ViewModel.
I have a Button on in the View that I have bound to a RelayCommand in the ViewModel but I also want to pass a CommandParameter to the Command.
The dynamically create controls are of types ListBox, ComboBox, TreeView, RadionButton and CheckBox. So when I press the Button I want to get all selected/checked items in the controls and pass this a List with the CommandParamter.
I have figured out how to search for all selected/checked items and get the object of type Code(class name) and put them in a List if I use the Click event on the Button. I want to use the RelayCommand instead of using Click Event.
I have managed to bind the CommandParameter to the a Property that calls GetAllSelectedCheckedCodes() but it is only bound when the View is created.
Is it possible to have a property in the code behind that calls the function GetAllSelectedCheckedCodes() that is bound first when the Button Command is triggered.
Or is it possible to have multiple controls add/remove items in a List in the ViewModel when they are selected/unselected or checked/unchecked?
Are you able to add a property to your class like IsSelected, or IsActive, and bind that to the the IsSelected or IsChecked property of the control? Then, when you want to act on the selected items, you could just grab all the items in the collection where IsActive == true.
I have a Listbox that I binds to a resource (sort) CollectionViewSource in my XAML. Then in my cs code I set the CollectionViewSource source to List of objects (class level field)
I then have "remove button" that checks the selected items in the Listbox and removes them from the List of objects (class level field).
I thought the Listbox should update automatically since the items source updated.
Am I missing a step or property setting ?
Or am I missing something about how binding works?
tep
The class that contains your list of objects must implement INotifyPropertyChanged and you must raise the notification event when the list changes, passing in the name of the property that changed. This is what notifies the UI that it must update anything bound to that property.
Alternatively, make your collection of objects an ObservableCollection<T> and that will do the notifying for you.
Kind of an odd question- if I'm thinking of this the wrong way please let me know. I am using an infragistics dock manager, which manages tabs as well. So I can create a TabGroupPane, and then add multiple ContentPanes, each of which has its own tab.
In each content pane, I set my viewmodel:
<ContentPane>
<viewmodels:MyViewModelForTab1 />
</ContentPane>
So here's the problem- while using a mediator pattern for communication, my viewmodels have no idea if they are on the visible tab or not, so they are always working even if hidden. The TabGroupPane does have a SelectedTab property, as well as each ContentPane having an IsActive property.
So the question is how do I set that information in my ViewModel? Making my VM a dependency object seems like a bad idea since I already implement INotifyPropertyChanged. Using a CLR prop in my VM also doesnt work, since you cannot bind to it.
How can I get my VM to know if it is the datacontext of an active tab?
Thanks!
I would put an IsSelected property on my ViewModel and bind it to the TabItem's IsSelected dependency property.
This should allow you to hook into when it is updated and perform whatever you need. You don't need a mediator pattern here since you are communicatining from the View to the ViewModel.
Make sure your ViewModel is bound to the DataContext property of the view (specifically, that the Tab's DataContext is the ViewModel). The way you have it now, your ViewModel is the content of the element, not bound to the DataContext, as it should be:
<Tab.Resources>
<viewmodels:MyViewModelForTab1 x:Key="Tab1ViewModel" />
</Tab.Resources>
<ContentPane DataContext="{StaticResource Tab1ViewModel}" />
Or something like that...
I don't know the Infragistics model, so my apologies if this is inapposite, but here's how I implement this with regular items controls - tab control, list box, whatever.
Create a container view model class that includes an observable collection of items and exposes a SelectedItem property. Make the container class the data context of the items control. Bind the items control's SelectedItem property to the container class's.
Hook the item objects up to the PropertyChanged event of the container. So now when the selected item in the UI changes, the container view model notifies all of the items that SelectedItem has changed. Each item object's event handler can determine for itself whether or not it's now the selected item.
The item objects thus don't know any implementation details of the UI - you can unit test your classes outside of a UI and the logic will still work correctly.
I have a silverlight control (View) which displays a list of items in a specified property of the datacontext (viewmodel).
What I need is for the scrollviewer in my control to scroll to the top or bottom depending on where the latest item has been added to the list. (It'll always be either the beginning or the end of the list, I don't need to worry about middle of list insertions.)
In WPF i'd just use the DataContextChanged event to start listening to the viewmodel, but in silverlight that event is internal.
Any ideas on how to tackle this?
A good starting point is Attached Behaviors on CodeProject.
A useful behavior would watch the ListBox.ItemsSource and attach to the observable collection when set. On the collection changed event, use ListBox.ScrollIntoView to display the changed item.
I can't use the CollectionChangedEvent of ObservableCollection since I need the DataContextChanged event to get the DataContext which holds the Collection in the first place.
Would you not do this in the ViewModel?
Whatever ViewModel has the ObservableCollection, expose a property of type T named SelectedItem and whenever the ObservableCollection changes with a new item, the CollectionChanged event will allow you to set the SelectedItem property. Once this is done, wire up the SelectedItem in the control to this property on your ViewModel.
This will obviously only work with controls like ListBox where a SelectedItem property exists.
In place of DataContextChanged in WPF , you can use CollectionChanged event of ObservableCollection. In the collection changed you will get to know the NewItem Index.