permanently sorting a collection

I have an observable collection that is exposed to the user by a collectionviewsource. One of the properties on the items in the collection is sortorder. I am trying to allow the user to permanently resort this collection and propagate the changes to the db.

I have the CVS working where I can resort the individual items as they are displayed in the listbox.开发者_Go百科 Now however I have to change the item.sortorder==cvs.currentindex and i am having trouble figuring out the proper way to do this.

EDIT

evidently I was not clear enough. Sortorder is a field in my DB that is part of my object that allows the user to control position of the items as displayed in list controls. I am trying to give my user the ability to change how these items are sorted in the future by changing the value of the sortorder field to equal the current index of the displayed item.

items current sortorder value is 3.

user moves displayed listitem to position 0(ie first position)

items new sortorder=0 item with original sortorder will become 1 etc

this would be achieved by looping through the sorted CVS and making Item.SortOrder= CVS.Item.index

Databases return rows from table based typically on the order they were added to the table unless you specify an order by clause in your query. changing the order in the database is not a good idea. instead, try something such as using a parameterized query and passing in the column and direction you wish to be sorted which is retrieved from a user preference.

I figured it out.

I went back and looked at the code that I was using to change the position of the elements and I am actually using the collection itself:

private void OnDecreaseSortOrderCommandExecute()
        {
            int index = QuestionsCVS.View.CurrentPosition;
            QuestionsViewModel item = SelectedQuestionVM;

            if (item != null && index > 0)
            {
                SortableQuestionsVMCollection.RemoveAt(index);
                SortableQuestionsVMCollection.Insert(index - 1, item);
                QuestionsCVS.View.Refresh();
                QuestionsCVS.View.MoveCurrentTo(item);
            }
        }

So I simply did this:

private void ResortSortableQuestionsVMCollection()
        {
            for (int i = 0; i < SortableQuestionsVMCollection.Count; i++)
            {
                SortableQuestionsVMCollection[i].SortOrder = i;
            }
        }

I dont know if this will work in every circumstance but it certainly did what I wanted for this one.