def syncCoursesWith( courseList ) {
    removeCoursesNotIn(courseList)
    addCourseIn(courseList)
  }

  def removeCoursesNotIn( courseList ) {
    def coursesToRemove = courseOfferings.findAll {!(it.course in courseList)}
    coursesToRemove.each {
println("==================================> " + it)
      removeFromCourseOfferings(it)
      it.delete(flush:true)
    }
  }

  def addCourseIn( courseList ) {
    def existingCourses = courseOfferings*.course
    def toAdd = courseList.findAll { !(it in existingCourses) }
    toAdd.each { addToCourseOfferings(new CourseOffering(course: it)) }
    save()
  }