Question

I have a combobox that is bound to ObservableCollection<Item> in the ViewModel. When a user adds a new item I don’t know if they’ve added an item to the bound collection so I do a refresh. Well this sets the selecteditem to null so I implemented some code to remember the selected item and set it after the Collection is renewed. The problem is the collection doesn’t display the selecteditem.

if (_selectedBrand != null)
{
    int selectedBrandID = _selectedBrand.BrandID;
    Brands = null;
    Brands = new ObservableCollection<Brand>(_dataContext.Brands.ToList());
    SelectedBrand = _dataContext.Brands.First<Brand>(b => b.BrandID == selectedBrandID);
}

How can I get the collection to display the corrected item?

Edit: The collection represents a table in the backend DB. The user can open a new window to add items to the DB. Once the window is closed I must refresh the collection to get any new items. Sorry for the confusion of my wording.

Answer 1

Can you not just retrieve the new collection, and then update the existing one adding in the missing values (using the linq extension except?)