Cross threading exception accessing viewmodel property set from code behind - wpf

Question

I have a WPF MVVM app that displays drug information in a telerik grid view. I want to do some filtering and paging in the view model but I keep getting cross-thread exceptions. The initial load works fine. I can change pages/page size without a problem. When I filter the grid, I create an IEnumerable of FilterDescriptors in the code behind and then set it on the Filters property of the view model. At this point, I get the cross-thread exception when doing the query using the filters. I have tried everything I can think of but can't get it to work.
public partial class DrugEdit : Page
{
public DrugEdit()
{
InitializeComponent();
}
private void RadGridView1_Filtered(object sender, Telerik.Windows.Controls.GridView.GridViewFilteredEventArgs e)
{
DrugEditViewModel vm = this.DataContext as DrugEditViewModel;
Telerik.Windows.Controls.RadGridView gv = sender as Telerik.Windows.Controls.RadGridView;
if (gv.FilterDescriptors == null || gv.FilterDescriptors.Count == 0)
vm.Filters = null;
else
{
List<FilterDescriptor> filters = (vm.Filters==null? new List<FilterDescriptor>(): vm.Filters.ToList());
foreach (FilterDescriptor r in e.Removed)
{
var fnd = filters.FirstOrDefault(x => x.Member == r.Member);
if (fnd == null) continue;
filters.Remove(fnd);
}
foreach (FilterDescriptor a in e.Added)
{
var fnd = filters.FirstOrDefault(x => x.Member == a.Member);
if (fnd == null)
{
filters.Add(new FilterDescriptor(a.Member, a.Operator, a.Value, false, a.MemberType));
}
else
{
fnd.Operator = a.Operator;
fnd.Value = a.Value;
}
}
vm.Filters = filters;
}
}
}
public class DrugEditViewModel
: ViewModelBase
{
private Data.DBContext ctx = new Data.DBContext();
private List<FilterDescriptor> FiltersValue = new List<FilterDescriptor>();
public List<FilterDescriptor> Filters
{
get { return FiltersValue; }
set
{
SetPropertyValue((() => Filters), ref FiltersValue, value);
RecordCount = 0;
LoadData();
}
}
private int PageValue = 0;
public int Page
{
get { return PageValue; }
set
{
SetPropertyValue((() => Page), ref PageValue, value);
LoadData();
}
}
private int PageSizeValue = 20;
public int PageSize
{
get { return PageSizeValue; }
set
{
SetPropertyValue((() => PageSize), ref PageSizeValue, value);
Page = 0;
}
}
private int RecordCountValue;
public int RecordCount
{
get { return RecordCountValue; }
set
{
SetPropertyValue((() => RecordCount), ref RecordCountValue, value);
}
}
private ObservableCollection<Models.Drug> DrugsValue;
public ObservableCollection<Models.Drug> Drugs
{
get { return DrugsValue; }
set
{
SetPropertyValue((() => Drugs), ref DrugsValue, value);
}
}
#endregion
#region Methods
private void LoadData()
{
if (ctx == null)
ctx = new Data.DBContext();
//load record count if we don't have it.
if (RecordCount == 0)
{
IsBusy = true;
Task.Run(() =>
{
if (Filters == null || Filters.Count() == 0)
{
RecordCount = ctx.Set<Entities.Drug>().Count();
}
else
{
RecordCount = ctx.Set<Entities.Drug>().Where(Filters).Count();
}
IsBusy = false;
LoadData();
});
return;
}
IsBusy = true;
Task.Run(() =>
{
if (Filters == null || Filters.Count() == 0)
currentPage = (from d in ctx.Query<Entities.Drug>()
orderby d.NDC
select d)
.Skip(PageSize * Page)
.Take(PageSize).ToList();
else
currentPage = (from d in ctx.Query<Entities.Drug>()
orderby d.NDC
select d)
.Where(Filters)
.Skip(PageSize * Page)
.Take(PageSize)
.ToIList() as List<Entities.Drug>;
Drugs = new ObservableCollection<Models.Drug>((from c in currentPage
select new Models.Drug(c)));
IsBusy = false;
});
}
#endregion
}