Why does the IEnumerable.Select() works in 1 of 2 cases ? Can not be inferred from usage

Question

I get this error message:

The type arguments for method \'System.Linq.Enumerable.Select(System.Collections.Generic.IE         


        

Answer 1

Select is not a replacement for a foreach. Use this instead:

ObservableCollection documentsOC = new ObservableCollection();
IEnumerable documents = _docRepo.GetDocumentsByPupilId(_selectedPupil.Id);
foreach(var doc in documents)
{
    documentsOC.Add(doc);
}
SelectedPupil.Documents.DocumentList = documentsOC;