def student_library_details
@current_user = current_user
@available_modules = Configuration.available_modules
@config = Configuration.find_by_config_key('NetworkState').config_value
@student = Student.find(params[:id])
#@reserved = @student.book_reservations
#@borrowed = @student.book_movements
end

I put comments in:
#@reserved = @student.book_reservations
#@borrowed = @student.book_movements
because it shows error in student profile...