创建新实体加关联不起作用 [英] Creating new entity plus association not working

问题描述

我有两个实体 AppUser 和 UserGroup.他们有一个 @ManyToMany 关系.

I am having two entities AppUser and UserGroup. They have a @ManyToMany relationship.

我目前正在尝试为现有用户创建和关联一个新组，如下所示:

I am currently trying to create and associate a new group for an existing user like this:

POST http://localhost:8080/groups

{
  "name": "Group 1", 
  "users": ["http://localhost:8080/users/1"]
}

问题是只创建了组 - 但与列出的用户没有关联 - 服务器仍然响应 201 Created?!

The problem is that only the group gets created - but no association with the listed users - and still the server responds with 201 Created?!

这是两个存储库:

@RepositoryRestResource(collectionResourceRel = "users", path = "users")
public interface AppUserRepository extends JpaRepository<AppUser, Long> {
    AppUser findByUsername(@Param("username") String username);
}

@RepositoryRestResource(collectionResourceRel = "groups", path = "groups")
public interface UserGroupRepository extends JpaRepository<UserGroup, Long> {
    List<UserGroup> findByName(@Param("name") String name);
}

下面你可以看到关系是如何定义的:

Below you can see how the relation is defined:

AppUser.java

AppUser.java

@Column(name="user_group_id")
@ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
@JoinTable(name = "app_user__user_group",
        joinColumns = {
                @JoinColumn(name = "app_user_id", nullable = false, updatable = false) },
        inverseJoinColumns = {
                @JoinColumn(name = "user_group_id", nullable = false, updatable = false)})
private Set<UserGroup> groups;

用户组.java

@Column(name = "app_user_id")
@ManyToMany(fetch = FetchType.LAZY, mappedBy = "groups")
private Set<AppUser> users;

<小时>

注意:

如果我只传递一个字符串，而不是 users 的列表:

If I pass just a string, not a list for users:

POST http://localhost:8080/groups

{
  "name": "Group 1", 
  "users": "http://localhost:8080/users/1"
}

我得到的是:

{
  "cause": {
    "cause": null,
    "message": "Cannot deserialize instance of java.util.Set out of VALUE_STRING token at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 7, column: 12] (through reference chain: mahlzeit.api.hibernate.model.UserGroup["users"])"
  },
  "message": "JSON parse error: Cannot deserialize instance of java.util.Set out of VALUE_STRING token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of java.util.Set out of VALUE_STRING token at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 7, column: 12] (through reference chain: mahlzeit.api.hibernate.model.UserGroup["users"])"
}

推荐答案

try

@Column(name = "app_user_id")
@ManyToMany(fetch = FetchType.LAZY, mappedBy = "groups",cascade = CascadeType.ALL)
private Set<AppUser> users;

最终通过用户列表

{
  "name": "Group 1", 
  "users": ["http://localhost:8080/users/1"]
}

for Cannot deserialize instance of java.util.Set 错误它需要一个用户列表，而不是单个用户的实例

for Cannot deserialize instance of java.util.Set error it expect a list of users not instans of single user

这篇关于创建新实体加关联不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！