CODEWITHSUNDEEP
c#wpfdata-binding
Toadums
Toadums

Reputation: 2812

how to make an ItemsSource not in use?

I have a DataGrid in WPF (a class that extends DataGrid), and I would like to edit the items in it. But of course I am getting the following error:

Operation is not valid while ItemsSource is in use. 
Access and modify elements with ItemsControl.ItemsSource instead.

I have tried changing the itemsSource of the DataGrid, and then adding the items, but I still get the same error. Something like:

public class MyDG:DataGrid{

    public void add(){
        List<TimesheetRecord> records = new List<TimesheetRecord>();

        foreach(TimesheetRecord rec in this.Items){
            records.Add(rec);
        }

        //DO SOME STUFF, ADD MORE ITEMS TO records

        ItemCollection col = this.Items;
        this.ItemsSource = records;
        col.Clear();

       foreach(TimesheetRecord rec in records){
            col.add(red);//exception thrown here
        }

        this.ItemsSource = col;
    }

}

I don't understand why I am getting that error, when I have already changed the itemsSource to a different list...?

I can't (easily) add the items to the list which is originally bound as the itemsSource, because that list exists in a different class. Would it be best for me to just have a global variable in the MyDG class that is List<TimesheetRecord> myItems = new List<TimesheetRecord>(); and then in the constructor for MyDG go this.ItemsSource = myItems

Or do you have any other suggestions how I should go about doing this? I am open to anything, as this is the first time I have used databinding, so I am probably doing something wrong...

Upvotes: 1

Views: 5063

Answers (3)

McGarnagle
McGarnagle

Reputation: 102783

You have to choose whether to use Items or ItemsSource, you can't use both interchangably. Attempting to modify Items while using ItemsSource assumes an implicit conversion that isn't supported, hence the error.

In this case, it seems like the best approach might be to just set Items and add to that collection directly. To use ItemsSource, you'd need to, exactly as you wrote, pass a reference to the ItemsSource collection (List<TimesheetRecord>) in to your DataGrid class.

Upvotes: 2

Volma
Volma

Reputation: 1345

Decalre records collection as:

ObservableCollection<TimesheetRecord> records = new ObservableCollection<TimesheetRecord>();

and keep it data-bound to the DataGrid. Manipulate records collection as needed, data binding will take care of keeping UI in sync with the collection.

Upvotes: 4

Breealzibub
Breealzibub

Reputation: 8095

Once you assign "records" to the ItemsSource, you've already updated your collection. There's no need to manually add items to the dataGrid.Items collection.

Upvotes: 1

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