             student = @get_student(student)
             student_id = student.get('student_id')
             info =
-                last_assignment    : assignment.get('last_assignment')?.get(student_id)?.toJS() ? {}
-                last_collect       : assignment.get('last_collect')?.get(student_id)?.toJS() ? {}
-                last_return_graded : assignment.get('last_return_graded')?.get(student_id)?.toJS() ? {}
+                last_assignment    : assignment.get('last_assignment')?.get(student_id)?.toJS()   # important to be undefined if no info -- assumed in code
+                last_collect       : assignment.get('last_collect')?.get(student_id)?.toJS()
+                last_return_graded : assignment.get('last_return_graded')?.get(student_id)?.toJS()
                 grade              : assignment.get('grades')?.get(student_id)
                 student_id         : student_id
                 assignment_id      : assignment.get('assignment_id')

    copy: (type, assignment_id, student_id) ->
        @props.flux.getActions(@props.name).copy_assignment(type, assignment_id, student_id)

    render_last: (name, obj, type, info) ->
        open = => @open(type, info.assignment_id, info.student_id)
        copy = => @copy(type, info.assignment_id, info.student_id)
        v = [<span key='name'>{name+': '}</span>]

        @props.flux.getActions(@props.name).copy_assignment_from_all_students(@props.assignment)

    render_collect_button: ->
        # disable the button if nothing ever assigned
        <Button onClick={@collect_assignment} disabled={(@props.assignment.get('last_assignment')?.size ? 0) == 0}>
            <Icon name="share-square-o" rotate="180" /> Collect from all...
        </Button>

    return_assignment: ->
        # Assign assignment to all (non-deleted) students.
        @props.flux.getActions(@props.name).return_assignment_to_all_students(@props.assignment)

    render_return_button: ->
        # Disable the button if nothing ever collected.
        <Button onClick={@return_assignment} disabled={(@props.assignment.get('last_collect')?.size ? 0) == 0}>
            <Icon name="share-square-o" /> Return to all...
        </Button>

