public List <string> CoursesForInvoice()
{
return(MethodBase.GetCurrentMethod().Cache(() => {
var sectionIds = SectionService.GetTreeWithSubsections()
.Where(x => Sections.ForInvoice.Contains(x.Section_ID))
.SelectMany(x => x.SubSections).Select(x => x.Section_ID).ToList();
return CourseService.GetCourseTCListForSections(sectionIds);
}));
}
