java - 更新表会删除jsp页面中未绑定(bind)的列中的数据

Question

我有一个有很多列的表。当我使用@ModelAttribute更新某些列时，jsp页面中未指定的列中的数据将被删除。

示例

@RequestMapping(value= "/studenteducation", method= RequestMethod.GET)
public String setupUpdateEducationForm(Model model, @ModelAttribute("education") Student student){

    student = studentService.getStudent(getStudentName());
    model.addAttribute("education", student);  //adding saved student data into model
    return "studenteducation";
}

@RequestMapping(value= "/studenteducation", method= RequestMethod.POST)
public String studentEducationForm(Model model, @ModelAttribute("education") Student student, BindingResult result){

    if(result.hasErrors()){
        return "studenteducation";          
    }

    student.setStudentId(getStudentName()); // inserting primary key
    studentService.updateStudent(student);  // updating student table

    return "redirect:/";        
}

问题是我没有绑定(bind)此更新中的所有列，因此只留下绑定(bind)的列数据，而其他列数据则从数据库中删除。我有大约 15 列，我在此 jsp 页面中绑定(bind) 5 列。

我的完整 Controller 代码:

@Controller
@RequestMapping("/user")
@SessionAttributes("education")
public class StudentController {

@Autowired
StudentService studentService;
Student student = new Student();

// Setup new Student form------------------------------------------------------------------ 

@RequestMapping(value= "/newuser", method= RequestMethod.GET)
public String setupAddStudentForm(Model model, @ModelAttribute("student") Student student){

    return "registerstudent";
}

// Add new Student------------------------------------------------------------------    

@RequestMapping(value= "/newuser", method= RequestMethod.POST)
public String sddStudent(Model model, @ModelAttribute("student") Student student, BindingResult result, SessionStatus sessionStatus){

    if(result.hasErrors()){
        return "registerstudent";
    }
    studentService.addStudent(student); 
    sessionStatus.setComplete();
    return "redirect:/";
}

// Setup Edit Profile Form------------------------------------------------------------------    

@RequestMapping(value= "/updateprofile", method= RequestMethod.GET)
public String setupStudentProfileForm(Model model, @ModelAttribute("profile") Student student ){

    Student stu = studentService.getStudent(getStudentName());
    model.addAttribute("name", student.getStudentId());
    model.addAttribute("studentprofile", stu);
    return "studentprofile";        
}

// Update student profile------------------------------------------------------------------ 

@RequestMapping(value= "/updateprofile", method= RequestMethod.POST)
public String studentProfileForm(Model model, @ModelAttribute("profile") Student student, BindingResult result, SessionStatus sessionStatus ){

    if(result.hasErrors()){
        return "studentprofile";            
    }

    student.setStudentId(getStudentName());
    studentService.updateStudent(student);      
    sessionStatus.setComplete();
    return "redirect:/";        
}

// Setup Update Education Form------------------------------------------------------------------    

@RequestMapping(value= "/studenteducation", method= RequestMethod.GET)
public String setupUpdateEducationForm(Model model, @ModelAttribute("education") Student student){

    student = studentService.getStudent(getStudentName());
    model.addAttribute("education", student);
    return "studenteducation";
}

// Update Student Education------------------------------------------------------------------   

@RequestMapping(value= "/studenteducation", method= RequestMethod.POST)
public String studentEducationForm(Model model, @ModelAttribute("education") Student student, BindingResult result, SessionStatus sessionStatus){

    if(result.hasErrors()){
        return "studenteducation";          
    }

    student.setStudentId(getStudentName());
    studentService.updateStudent(student);
    sessionStatus.setComplete();
    return "redirect:/";        
}

我的学生模型 ID 很大，我正在通过 2 个 Controller 更新它。不同jsp页面中的学生资料和具有不同 Controller 的不同jsp页面中的教育。当我更新一部分时，另一部分会删除。

Answer 1

这是 Spring MVC 和 Hibernate 协同工作的方式。当您在 Controller 方法中编写 @ModelAttribute("education") Student Student 时，Spring MVC 会创建一个新对象并用表单数据填充它。所有其他字段保留其初始化值(通常为空)。 你可能会觉得这很愚蠢，但我从未在 Spring MVC 中找到一种好的、干净的方法来处理这个问题。常见的解决方法:

• 按照 Neil McGuigan 的建议使用 SessionAttributes。问题在于，当您不再需要该属性时，它可以保留在 session 中，并且它显然不能用于无 session API 使用。
• 在 URL 中传递 ID，并使用 Converter 将其转换为正确的 Student 对象。但你必须在服务层之外调用持久层。