public async Task <CursosResponse> AddStudent(string id, string studentId) { var existingCourse = await _cursosRepository.FindByIdAsync(id); if (existingCourse == null) { return(new CursosResponse("The student must have an existing course id")); } existingCourse.id_estudiante.Add(studentId); try { _cursosRepository.Update(existingCourse); return(new CursosResponse(existingCourse)); } catch (Exception ex) { return(new CursosResponse($"An error occurred adding the student to the course: {ex.Message}")); } }