Question

I want to set the listview datacontext equal to an observable collection so that changes to the collection may reflect on my listview. I create the observable collection as:

public static ObservableCollection<T> ToObservableCollection<T>(IEnumerable<T> enumeration)
{
     return new ObservableCollection<T>(enumeration);
}

private void UserControl_Loaded(object sender, RoutedEventArgs e)
{

           Entities.DatabaseModel m = new Entities.DatabaseModel();
           var q = from t in m.TimeSheet                            
                    join emp in m.Employees on t.idEmployee equals emp.id
                    where emp.id == CurrentEmploye.id
                    select new
                    {
                        firstName = emp.firstName,
                        lastName = emp.lastName,
                        position = emp.position,
                        clockInDate = t.clockInDate,
                        clockOutDate = t.clockOutDate,
                    };
           // here I create the observablecollection!!!!!!!!!!!!!!
           listView1.DataContext = ToObservableCollection(q); 
}

now my problem is that if I want to add items to the ObservableCollection how can I do that? If I do listView1.DataContext.Add( that will result on an error.

In other words I have the method

    private void btnClockIn_Click(object sender, RoutedEventArgs e)
    {
         // I will like to add items to the observable collection in here

---

This is what I have tried and it does not work:

    dynamic collection; 


private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
       // CurrentEmploye some employee
       Entities.DatabaseModel m = new Entities.DatabaseModel();
       var q = from t in m.TimeSheet                            
                join emp in m.Employees on t.idEmployee equals emp.id
                where emp.id == CurrentEmploye.id
                select new
                {
                    firstName = emp.firstName,
                    lastName = emp.lastName,
                    position = emp.position,
                    clockInDate = t.clockInDate,
                    clockOutDate = t.clockOutDate,
                };

       collection = ToObservableCollection(q); 
 }


    private void btnClockIn_Click(object sender, RoutedEventArgs e)
    {

         collection.Add(new
                {
                    firstName = "Antonio",
                    lastName = "Nam",
                    position = "Amin",
                    clockInDate = DateTime.Now,
                    clockOutDate = DateTime.Now
                });

Answer 1

You can ‘trick’ it by using a similar ‘template’ anonymous variable…
e.g. code method would be something like…

static ObservableCollection<T> CastToEnumerable<T>(this T template, object value)
{
    return (ObservableCollection<T>)value;
}

…and use it something like this…

var list = new
{
    firstName = "",
    lastName = "",
    position = "",
    clockInDate = DateTime.MinValue,
    clockOutDate = DateTime.MinValue
}.CastToEnumerable(context);
foreach (var value in list)
{ 
}

…it’s still recommendable to have a normal named class for your purpose.
You can find more info about similar problem here…
Cast to Anonymous Type
(Basically you cannot return anonymous type – short of tricks like this – ‘inferring’ of the type is what’s behind this).