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

c#, listview, multiple-columns, wpf, xml

Solution

You're binding the `ItemsSource` to a property in the `DataContext` called `Items`, so to update the collection, you need to go to the `Items` property in the `DataContext` and clear it.

In addition, the `Items` property needs to be of type `ObservableCollection`, not `List` if you want it to update the UI whenever the underlying collection changes.

Your bit of code that sets the `ItemsSource` in the code behind is not needed and should be removed. You only need to set the `ItemsSource` in one place, not both.

Here's a simple example of how it can work:

// Using Students instead of Items for the PropertyName to clarify
public ObservableCollection<Student> Students { get; set; }

public MyConstructor()
{
    ...

    Students = search.students();
    listBoxSS.DataContext = this;
}

Now when you have:

<ListView ItemsSource="{Binding Students}" ... />

you're binding the `ItemsSource` to the `ObservableCollection<Student>`, and when you want to clear the list you can call:

Students.Clear()

Problem

I am new in Binding and WPF recently I've learned how to create a `listBox` with multiple columns using Binding tech ``` <ListView ItemsSource="{Binding Items}" Margin="306,70,22,17" MouseDoubleClick="listBoxSS_MouseDoubleClick" Name="listBoxSS" > <ListView.View> <GridView> <GridView.Columns> <GridViewColumn Header="first_name " Width="100" DisplayMemberBinding="{Binding Path=First_name}" /> <GridViewColumn Header="last_name" Width="100" DisplayMemberBinding="{Binding Path=Last_name}" /> <GridViewColumn Header="phone_number" Width="100" DisplayMemberBinding="{Binding Path=Phones[0]}" /> <GridViewColumn Header="notes" Width="100" DisplayMemberBinding="{Binding Path=Notes}" /> </GridView.Columns> </GridView> </ListView.View> </ListView> ``` and this is the code: ``` List<Student> arr = search.students(); listBoxSS.ItemsSource = arr; ``` but the problem was when I tried to use add or remove item or clear ``` listBoxSS.Items.Clear(); ``` Please I need an example for using the items source or the way that I can ADD or Remove Item or Clear the list. EDIT: ``` <ListView ItemsSource="{Binding Items}" Margin="306,70,22,17" MouseDoubleClick="listBoxSS_MouseDoubleClick" Name="listBoxSS" > <ListView.View> <GridView> <GridView.Columns> <GridViewColumn Header="first_name " Width="100" DisplayMemberBinding="{Binding Path=First_name}" /> <GridViewColumn Header="last_name" Width="100" DisplayMemberBinding="{Binding Path=Last_name}" /> <GridViewColumn Header="phone_number" Width="100" DisplayMemberBinding="{Binding Path=Phones[0]}" /> <GridViewColumn Header="notes" Width="100" DisplayMemberBinding="{Binding Path=Notes}" /> </GridView.Columns> </GridView> </ListView.View> </ListView> ``` and here is the code: ``` ObservableCollection<Employee> Gemployees; var employees = new ObservableCollection<Employee>(search.employees()); ``` `search.employees()` get the list of all employees in my DB ``` listBoxPE.ItemsSource = employees; Gemployees = employees; ``` now I can perform all the methods on Gemployees ``` Gemployees.Remove((Student)listBoxSS.SelectedItem); Gemployees.Add((Student)listBoxSS.SelectedItem); ``` The `ListView` perform a refresh whenever I add or remove an Item from Gemployees!! Cool but still a little hard work on binding. Now I am doing an interface class to every ListView so I can put my stuff into it. It wont perform any flexibility in Adding Items.

Original source