问题描述
美好的一天。我遇到了一个问题：我试图发送带有一些属性的POST请求，但是我收到了错误的请求响应。这里是我的控制器：
@Controller
@RequestMapping（/ group）
public class GroupController {
private static org.apache.log4j.Logger logger = org.apache.log4j.Logger
.getLogger（GroupController 。类）;
@Autowired
私人GroupService groupService;
@RequestMapping（value =/ add，method = RequestMethod.POST）
public String addGroup（@ModelAttribute（group）final Group group）{
GroupController.logger.info（我在POST方法）;
this.groupService.addGroup（group）;
返回重定向：/学生/添加;
$ / code $ / pre
这是我的实体：
@Entity
@Table（name =university_groups）
public class Group implements Serializable {
private static final long serialVersionUID = 1L;
@OneToMany（fetch = FetchType.EAGER，cascade = CascadeType.ALL，mappedBy =group）
Set< Student>学生们;
@ManyToOne（fetch = FetchType.EAGER，cascade = CascadeType.ALL）
@NotNull
@JoinColumn（name =department_id）
私人部门部门;
@Id
@Column（name =group_name，unique = true，nullable = false）
private String group;
公共集团（）{
}
公共集团（最终字符串组，最终部门部门）{
this.group = group;
this.department = deparment;
}
public Department getDepartment（）{
return this.department;
}
public String getGroup（）{
return this.group;
}
public Set< Student> getStudents（）{
返回this.students;
}
public void setDepartment（final Department department）{
this.department = department;
}
public void setGroup（final String group）{
this.group = group;
}
public void setStudents（final Set& Student> students）{
this.students = students;
}
@Override
public String toString（）{
return this.group;
}
}
以下是JSP页面的一部分：
< form：form method =POSTaction =addcommandName =group>
< table>
< tr>
< td>< form：label path =group>
< spring：message code =label.student.group/>
< / form：label>< / td>
< td>< form：input path =group/>< / td>
< / tr>
< tr>
< td>< form：label path =department>
< spring：message code =label.student.department/>
< / form：label>< / td>
< td>< form：select path =department>
< form：options items =$ {departments}/>
< / form：select>< / td>
< td>< a href =< c：url value =/ department / add/>>< spring：message
code =label.student.addDepartment />< / a>< / td>
< / tr>
< tr>
< td colspan =2>< input type =submit
value =< spring：message code =label.student.addGroup/> />< / TD>
< / tr>
< / table>
< / form：form>
以下是部门实体：
<$ p $
@Table（name =departments）
public class Department实现可序列化{
private static final long serialVersionUID = 1L;
@Id
@Column（name =department，unique = true，nullable = false）
private String department;
@ManyToOne（fetch = FetchType.EAGER，cascade = CascadeType.ALL）
@NotNull
@JoinColumn（name =faculty_id）
私立教职员;
@OneToMany（fetch = FetchType.EAGER，cascade = CascadeType.ALL，mappedBy =department）
private Set< Group>组;
@ManyToMany（fetch = FetchType.LAZY）
@JoinTable（name =users_departments，joinColumns = {@JoinColumn（name =department_id，nullable = false，insertable = true， updatable = true）}，inverseJoinColumns = {@JoinColumn（name =user_name，nullable = false，insertable = true，updatable = true）}）
private Set< User>用户;
公共部门（）{
}
公共部门（最终字符串部门，最终教职员工）{
这个部门=部门;
this.faculty = faculty;
}
public String getDepartment（）{
return this.department;
}
公立学院getFaculty（）{
return this.faculty;
}
public Set< Group> getGroups（）{
return this.groups;
}
public Set< User> getUsers（）{
返回this.users;
}
public void setDepartment（final String department）{
this.department = department;
}
public void setFaculty（最终教职员工）{
this.faculty = faculty;
}
public void setGroups（final Set< Group> groups）{
this.groups = groups;
}
public void setUsers（final Set< User> users）{
this.users = users;
}
@Override
public String toString（）{
return this.department;
}
}
如果我删除@ModelAttribute（组）来自控制器方法的最终组群，一切正常。
请帮助我，我不明白为什么它不起作用。
除了Juergen Hoeller完全理解 @ModelAttribute 。这就好像他们创造了它来吓跑新人。他们真的需要改名为 @ReadModelAttribute 。
您不需要 @ModelAttribute 参数注释就可以使用POJO作为参数。
由于以下原因之一，您只需要它：
- 阅读
flashAttribute - 阅读
@SessionAttribute阅读 - Read a
flashAttribute - Read a
@SessionAttribute - Read a
@ModelAttribute method(which should be renamed to@WriteModelAttribute)
@ModelAttribute方法（应将其重命名为 @WriteModelAttribute ） 由于您没有执行其中的任何操作，因此请勿在此处使用 @ModelAttribute 参数注释。
Good day. I faced a problem: I'm trying to send POST request with some attributes, but I get "Bad request" response.
Here is my controller:
@Controller
@RequestMapping("/group")
public class GroupController {
private static org.apache.log4j.Logger logger = org.apache.log4j.Logger
.getLogger(GroupController.class);
@Autowired
private GroupService groupService;
@RequestMapping(value = "/add", method = RequestMethod.POST)
public String addGroup(@ModelAttribute("group") final Group group) {
GroupController.logger.info("I'm in POST method");
this.groupService.addGroup(group);
return "redirect:/student/add";
}
}
Here is my entity:
@Entity
@Table(name = "university_groups")
public class Group implements Serializable {
private static final long serialVersionUID = 1L;
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "group")
Set<Student> students;
@ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@NotNull
@JoinColumn(name = "department_id")
private Department department;
@Id
@Column(name = "group_name", unique = true, nullable = false)
private String group;
public Group() {
}
public Group(final String group, final Department deparment) {
this.group = group;
this.department = deparment;
}
public Department getDepartment() {
return this.department;
}
public String getGroup() {
return this.group;
}
public Set<Student> getStudents() {
return this.students;
}
public void setDepartment(final Department department) {
this.department = department;
}
public void setGroup(final String group) {
this.group = group;
}
public void setStudents(final Set<Student> students) {
this.students = students;
}
@Override
public String toString() {
return this.group;
}
}
Here is part of JSP page:
<form:form method="POST" action="add" commandName="group">
<table>
<tr>
<td><form:label path="group">
<spring:message code="label.student.group" />
</form:label></td>
<td><form:input path="group" /></td>
</tr>
<tr>
<td><form:label path="department">
<spring:message code="label.student.department" />
</form:label></td>
<td><form:select path="department">
<form:options items="${departments}" />
</form:select></td>
<td><a href="<c:url value="/department/add"/>"><spring:message
code="label.student.addDepartment" /></a></td>
</tr>
<tr>
<td colspan="2"><input type="submit"
value="<spring:message code="label.student.addGroup"/>" /></td>
</tr>
</table>
</form:form>
Here is Department entity:
@Entity
@Table(name = "departments")
public class Department implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@Column(name = "department", unique = true, nullable = false)
private String department;
@ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@NotNull
@JoinColumn(name = "faculty_id")
private Faculty faculty;
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "department")
private Set<Group> groups;
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "users_departments", joinColumns = {@JoinColumn(name = "department_id", nullable = false, insertable = true, updatable = true) }, inverseJoinColumns = {@JoinColumn(name = "user_name", nullable = false, insertable = true, updatable = true) })
private Set<User> users;
public Department() {
}
public Department(final String department, final Faculty faculty) {
this.department = department;
this.faculty = faculty;
}
public String getDepartment() {
return this.department;
}
public Faculty getFaculty() {
return this.faculty;
}
public Set<Group> getGroups() {
return this.groups;
}
public Set<User> getUsers() {
return this.users;
}
public void setDepartment(final String department) {
this.department = department;
}
public void setFaculty(final Faculty faculty) {
this.faculty = faculty;
}
public void setGroups(final Set<Group> groups) {
this.groups = groups;
}
public void setUsers(final Set<User> users) {
this.users = users;
}
@Override
public String toString() {
return this.department;
}
}
If I remove @ModelAttribute("group") final Group group from controller method, all is OK.Please, help me, I can't understand why it doesn't works.
No one except Juergen Hoeller understands @ModelAttribute fully. It's as though they created it to scare away new guys.
They really need to change the name to @ReadModelAttribute.
You don't need @ModelAttribute parameter annotation just to use a POJO as a parameter.
You only need it for one of the following reasons:
Since you aren't doing any of those, don't use @ModelAttribute parameter annotation here.
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