弹簧:无法提交表单编辑实体具有外键

Question

我有一个实体类 像这样的员工。它有一个对象部门(另一个实体(

@Entity
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;
    @NotNull
    @NotEmpty
    @Valid
    private String name;
    @DateTimeFormat(pattern="dd/MM/yyyy")
    @Valid
    private Date date;
    private String cmt;
    private String address;
    private String position;
    private Boolean matrimony = true;
    @ManyToOne
    @Valid
    private Department department;
}

控制器，

创建控制器显示编辑页面，并添加控制器解决添加请求：

@RequestMapping(value = "/employee/add", method = RequestMethod.POST) 
public String add(@Validated @ModelAttribute(value = "employee") Employee employee) {
    employeeRepository.save(employee);
    return "redirect:./list";
}
@RequestMapping(value = "/employee/create") 
public ModelAndView create(ModelMap mm) {   
    mm.addAttribute("action", "add");
    mm.addAttribute("employee", new Employee());
    mm.addAttribute("dao", new DepartmentDAO(departmentRepository));
    return new ModelAndView("../jsp/employee/edit.jsp");  
}

查看，它是输入员工数据并提交添加方法的形式。

<form:form method="POST" action="${website_url}" commandName="employee">
            <form:hidden path="id"></form:hidden>
            <div class="form-group">
                Name:
                <form:input path="name" class="form-control"></form:input>
            </div>
            <div class="form-group">
                Date of birth:
                <form:input path="date" class="form-control"></form:input>
            </div>                   
            <div class="form-group">
                ID card number:
                <form:input path="cmt" class="form-control"></form:input>
            </div>                   
            <div class="form-group">
                Address:
                <form:input path="address" class="form-control"></form:input>
            </div>                   
            <div class="form-group">
                Department:                     
                    <form:select path="department.id" class="form-control">
                        <% for(Department department : departmentDAO.departmentRepository.findAll()){%>
                            <form:option value="<%= department.getId() %>">
                                <%= department.getName() %>
                            </form:option>
                        <% } %>
                    </form:select>                      
            </div>                  
            <div class="form-group">
                Position:                      
                    <form:select path="position" class="form-control">
                        <form:option value="Director">Director</form:option>
                        <form:option value="Department Leader">Department Leader</form:option>
                        <form:option value="Employee">Employee</form:option>
                    </form:select>                      
            </div>                 
            <div class="form-group form-inline">
                Matrimony:
                <form:checkbox path="matrimony" class="form-control"></form:checkbox>
            </div>
            <input type="submit" value="save" class="btn btn-primary form-control" />
        </form:form>

我运行弹簧，它正确加载编辑页面。但是我提交了表格，由于外键部门，我收到了400 Bad请求。

Answer 1

JPA 很可能抱怨您将分离的 Department 实体传递给persist。

您应该使用一种服务方法，该方法将按照employee.setDepartment(departmentDAO.findById(employee.getDepartment().getId()))行调用某些内容，然后才调用employeeRepository.save(employee)。

或者，您可以将cascade = MERGE添加到您的@ManyToOne并在您的控制器中放置类似的代码行，尽管它在事务方面并不安全。