I'm trying to use a collection that is a property of another collection to bind to a listbox. The following works fine
<ListBox ItemsSource="{Binding Path=Locations[0].Buildings}">
the problem is that I need a dynamic index and
<ListBox ItemsSource="{Binding Path=Locations[index].Buildings}">
where index is an integer in my viewmodel, does not work. Does anyone know how I can associate the index in my xaml with the property in my viewmodel?
where index is an integer in my viewmodel, does not work. Does anyone know how I can associate the index in my xaml with the property in my viewmodel?
One simple option would be to just expose a CurrentLocation property within your ViewModel, which was effectively Location[index]. You could then bind to it directly.
A binding within a binding is not possible, So in XAML you can't bind to "index".
a. Chris Moser's method, You can create a DependencyProperty that binds to "index" Specify a change listener on the RegisterAttached handler and do your work there.
b. Use a Converter. You can provide index as the ConverterParameter
c. Bind to a POCO property. A POCO property would need its INotifyPropertyChanged signaled by the changer
Related
I'm trying to bind combobox editor in a PropertyGrid to a list.
<dxprg:PropertyGridControl SelectedObject="{Binding SelectedEmployee}">
<dxprg:PropertyDefinition Path="EmployeeCountryID">
<dxprg:PropertyDefinition.EditSettings>
<dxe:ComboBoxEditSettings
ItemsSource="{Binding Path=DataContext.Countries, ElementName=rootWindow}"
ValueMember="CountryId" DisplayMember="CountryName" />
</dxprg:PropertyDefinition.EditSettings>
</dxprg:PropertyDefinition>
</dxprg:PropertyGridControl>
This example is from a third-party control but the problem may be just general.
The "rootWindow" DataContext has been set to a ViewModel which holds a property List(of Country) that I want have as ItemsSource in a Combobox.
I was trying to access that list by setting the Combobox ItemsSource to the rootWindow.DataContext.Countries property but I don't get any data.
Tried also all those RelativeSource FindAncestor bindings but no data appeared either.
Why can't I bind through a DataContext of a given element like this?
This became solved. The problem was not with the binding at all but realated to how I defined the third-party control: Instead of EditSettings I should have defined CellTemplate -> DataTemplate.
I have a an object created in Xaml:
<Grid>
<MyObject/>
</Grid>
I need someway to bind the object myObject back to a property in my view model. I dont know whether this is possible, everything ive seen so far binds properties together, but any help would be greatly appreciated.
I am assuming what you want is your ViewModel to hold the actual visual control MyObject in it and your Grid to display it via MVVM.
This is possible through ContentControl in WPF.
Assuming your ViewModel has a property MyObjectView which holds MyObject...
<Grid>
<ContentControl Content="{Binding MyObjectView}" />
</Grid>
Having said that you must take caution that same MyObjectView is not bound to any other content control as that will result in an error
"Specified element is already the logical child of another element.
Disconnect it first"
And if that requirement is possible then you must excercise ContentTemplate option.
Let me know if this helps.
It is possible. It kinda breaks mvvm though.
You can attach an InvokeCommandAction to this object, and bind the CommandParameter to it via ElementBinding. Then in the callback of the command which you defined in the viewmodel, you will have a reference to this object from the CommandParameter.
I have a contextmenu, the itemsource is bound to an observable collection
i need to bind the MenuItem.Click to a command in my viewmodel..
HOW DO I DO THIS?
i have my own view model but the context menu items should be bounded to a different viewmodel..
Use RelativeSource Mode=FindAncestor to get to your parent Usercontrol and bind to the Path=DataContext.YourCommand. I believe you are trying to bind to the containing control's viewmodel.
If you dont like using RelativeSource, you can name your parent element and then using ElementName tag in the Binding extension:
If you want to bind between/cross different ViewModels, i believe you will have to use some sort of Event Broker/Aggregator. Have a look at Prism, it might give you some ideas
I have a property on a Silverlight control that a ViewModel wants to bind to. The ViewModel need to told of changes to the property NOT the other way around
Syntax like
<MyControl ViewPort="{Binding VMProperty}"/>
Declares ViewPort as the Target, in this instance ViewPort is the source of the data. I know I could make it TwoWay binding but that just seems wrong when i simply want one way but in the other direction.
Besides I do not want to make the property on the control a DependencyProperty because I do not want that property settable and I do not beleive that Silverlight supports read only dependency properties.
Is there a different way of setting up the Binding?
TIA
Pat Long
Maybe this works?
http://forums.silverlight.net/forums/p/141042/315359.aspx#315359
{Binding ElementName=TextBox1, Path=Text, Mode=TwoWay ,UpdateSourceTrigger=Explicit}
I want to create a usercontrol that takes lists of different objects. These objects would be assigned to the control at design time. Now I want to be able to use linq to object to sort this list inside the usercontrol. Can anyone give me any ideas as how to go about it?
Add a DependencyProperty of type ObservableCollection<T> to your user control class (call it MyItemsSource for example). In your containing XAML, bind that property to your Linq collection, and inside your user control, bind your ListBox (or other ItemsControl) to the property as follows:
{Binding
RelativeSource={RelativeSource
Mode=FindAncester,
AncestorType=UserControl},
Path=MyItemsSource}
Alternatively, you can set the Name property inside the user control on the top level element (the UserControl element) to for example MyUserControl, and bind against an ElementName instead of a RelativeSource as such:
{Binding ElementName=MyUserControl, Path=MyItemsSource}