传递选定的属性以发布来自表单的请求

Question

我有一个带有下拉菜单的表格：

<div class="form-group">
    <form:label path="departments">Dept. Code</form:label>
    <form:select path="departments" items="${departmentMap}" multiple="true" />

departmentMap来自控制器方法：

@RequestMapping(value = "/officeForm", method=RequestMethod.GET) 
public ModelAndView showOfficeForm() {
    ModelAndView result = new ModelAndView("officeForm", "command", new Office());
    List<Department> departmentsToDisplay = departmentServiceImpl.findAll();
    Map<Department, String> departmentMap = new HashMap<Department, String>();
    for (Department d : departmentsToDisplay) {
        departmentMap.put(d, d.getDepartmentName());
    }

    result.addObject("departmentMap", departmentMap);
            return result;
}

POST方法：

    @RequestMapping(value = "/addOffice", method = RequestMethod.POST)
    public ModelAndView updateOffice(@ModelAttribute("office") Office office, BindingResult result) {

        System.out.println("Office Name: " + office.getOfficeName());
        System.out.println("Departments: " + office.getDepartments());


         return new ModelAndView("result", "command", office);
    }

摘自Office.java：

@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "offices")
    private List<Department> departments;

来自Department.java的节选：

@ManyToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY)
    @JoinTable(name="OFF_DEPT_T",
    joinColumns={@JoinColumn(name="DEPT_ID", referencedColumnName="ID")},
    inverseJoinColumns={@JoinColumn(name="OFF_ID", referencedColumnName="ID")}
        )
    private List<Office> offices = new ArrayList<Office>();

如果我打印response.getAllErrors（），我得到：

Field error in object 'office' on field 'departments': rejected value [package.domain.Department@5597e5cf,package.domain.Department@2d14d0a7]; codes [typeMismatch.office.departments,typeMismatch.departments,typeMismatch.java.util.List,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [office.departments,departments]; arguments []; default message [departments]]; default message [Failed to convert property value of type 'java.lang.String[]' to required type 'java.util.List' for property 'departments'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [package.domain.Department] for property 'departments[0]': no matching editors or conversion strategy found]

有人可以告诉我如何传递对象但显示字符串吗？ 谢谢。

Answer 1

问题一：

由于您缺少列表departments初始化。 在将其放入模型之前，应先进行初始化，方法是替换：

  ModelAndView result = new ModelAndView("officeForm", "command", new Office());

有：

  Office office = new Office():
  office.setDepartments(new ArrayList<Department>()):
  ModelAndView result = new ModelAndView("officeForm", "command", office);

或者，如果您不想在控制器中初始化，则可以在创建Office对象时对其进行初始化，如下所示：

  private List<Department> departments = new ArrayList<Department>();

问题2：

要在select路径中绑定自定义对象（部门）列表时，需要向数据绑定器提供自定义属性编辑器，如下所示：

首先创建一个Property Editor类，如下所示：

public class DepartmentEditor extends PropertyEditorSupport {

    @Override
    public void setAsText(String text) throws IllegalArgumentException {
       Department department = new department();
       department.setName(text);
       setValue(department);
    }
}

然后通过注册来注册属性编辑器。 您可以通过将initBinder方法简单地放入控制器类中来进行注册，如下所示：

 @InitBinder
 public void initBinder(WebDataBinder binder) {
     binder.registerCustomEditor(Department.class, new DepartmentEditor());
 }

现在，您的代码应该可以正常工作。

Answer 2

我将命令绑定到新的office属性。

   @RequestMapping(value = "/officeSearch", method=RequestMethod.GET) 
public String showOfficesSearch(Model model) {
    model.addAttribute("command", new Office());
    return "officeSearch";
}