How can I refresh a combobox after modifying its ItemsSource ObservableCollection

Question

The problems is simple: when ItemsSource is updated Combobox doesn't "refresh" e.g. new items don't appear to be added to the list of items in the combobox.

I've tried the solution from aceepted answer to this question: WPF - Auto refresh combobox content with no luck.

here's my code, XAML:

<ComboBox Name="LeadTypeComboBox" ItemsSource="{Binding LeadTypeCollection}" />

ViewModel:

public ObservableCollection<XmlNode> LeadTypeCollection { get; set; }

the way I update this collection is in the separate method, which loads data from updated XML file: this.LeadTypeCollection = GetLeadTypesDataSource();

I've also tried using Add for testing purposes:

this.LeadTypeCollection = GetLeadTypesDataSource();
ItemToAdd = LeadTypeCollection[LeadTypeCollection.Count - 1];
this.LeadTypeCollection.Add(ItemToAdd);

the code updating collection definitely kicks off, I can see new items in this collection when debugging, but I don't see them in the combobox.

Doing this in the xaml code-behind works: LeadTypeComboBox.ItemsSource = MyViewModel.GetLeadTypesDataSource(); but I'd like to achieve this with MVVM, i.e. the code must be in ViewModel which isn't aware of LeadTypeComboBox control.

Answer 1

Firedragons answer would work, but i would prefer to initialize the LeadTypeCollection just once and use clear, add remove to update your collection.

var update = GetLeadTypesDataSource();     
this.LeadTypeCollection.Clear();

foreach(var item in update)
{
   this.LeadTypeCollection.Add(item);
}

your xaml binding should work if the datacontext is right

<ComboBox Name="LeadTypeComboBox" ItemsSource="{Binding LeadTypeCollection}" />