ListPicker Selection Items change according to preselected item

Question

Hi Aaron,
One last query, please.  I've got a 2 Listpicker fiels, Department and Role.  The Role is based on the selected Department.  For eg. if I select 'Technology' as a department the related roles are 'System Analyst, Business Analyst'. 
 I've tried using the following code in my XAML
ParentCategoryId="{Binding Source={x:Static local:NewUser.ListGuid}, Mode=OneWay}"
where ListGuid is defined at the very start of the form.
public static Guid ListGuid = new Guid("1fff3f06-31ae-bca2-136a-2e6a3ad29267");
In my code I set the RoleListPicker field with property 'GotFocus' to a new guid.
else if (DeptPicked1 == "Technology")
ListGuid = new Guid("c60d9514-56d7-6c51-5ae7-e2b11fb84e0b");
but it just doesn't work properly.  The form initially will pickup the first ParerntCategoryID and on subsequent updates will list the 2nd ParentCategoryID guid. Can you please let me know the best way to approach this.
Thnx
Sue.

Answer 1

Got it working..but it's not an MVVM approach, so technically this is a bad practice.
Instead of using "ListGuid" and binding to it, simply change the control's ParentCategoryId property.
So, let's say your Role listpicker's name is "RolePicker". Instead of
ListGuid = new Guid("blah-blah-blah");
Use this:
RolePicker.ParentCategoryId = new Guid("Blah-blah-blah");
Give that a try and let me know if it works for you.
Oh, and any time you change the parent category id, you should clear the selected item (afterall, logically, the selected item may not be apart of the new list of enumeration values)