[英]Getting nested entity data resulting in stackoverflow error
我在2表用戶和笑話之間有很多關系。 它們由連接表fav_joke連接,該表保存這些表中的id值。 根據我的設置,當II從這些表中插入和刪除時,它似乎可以正常工作。
問題是當我嘗試查詢User表以獲取所有關聯的笑話時。 再次工作正常,但以某種初始形式重復執行此操作,最終導致StackOverflow錯誤。 請參閱圖像以查看響應。 如您所見,我在玩笑中找到了一個用戶,該笑話又有自己的笑話,又有自己的用戶,而且還在不斷發展……
我期望在進行此查詢時在用戶下僅具有關聯的笑話,在這種情況下應為2,僅此而已。 我認為這與我在Joke實體中具有@ManyToMany關系注釋有關,但是我相信我需要這樣做。 請指教。 謝謝。
實體
@Getter
@Setter
@NoArgsConstructor
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
long memberId;
@ManyToMany
@JoinTable(
name = "fav_joke",
joinColumns = @JoinColumn(name = "memberId"),
inverseJoinColumns = @JoinColumn(name = "id")
)
private Set<Joke> jokes;
}
@Getter
@Setter
@NoArgsConstructor
@Entity
@Table(name = "joke")
public class Joke {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
private String question;
private String answer;
private boolean isFav;
@ManyToMany(mappedBy = "jokes")
private Set<User> users;
}
儲存庫
@Repository
public interface UserRepository extends JpaRepository<User, Long> {
User getUserByMemberId(long memberId);
}
@Repository
public interface JokeRepository extends JpaRepository<Joke, Long> {
@Query("select j from Joke j where j.id =:id")
Joke getJokeById(long id);
}
控制器-此調用是將堆棧溢出的調用。
@GetMapping("/get/fav/member_id/{memberId}")
public Set<Joke> getAllFavJokes(@PathVariable long memberId){
User user = userRepository.getUserByMemberId(memberId);
return user.getJokes();
}
我認為這無關緊要。 只是添加它以防萬一。 這樣做將填充由於多對多映射而在運行中創建的fav_joke表。
@GetMapping("/fav/joke_id/{id}/member_id/{memberId}/isFav/{isFav}")
public String toggleFavJoke(@PathVariable long id, @PathVariable long memberId, @PathVariable boolean isFav){
Joke joke = jokeRepository.getJokeById(id);
User user = userRepository.findById(memberId).orElse(null);
if(user != null && joke != null){
if(user.getJokes() != null){
if(isFav){
user.getJokes().remove(joke);
}else {
user.getJokes().add(joke);
}
}else {
if(!isFav){
user.setJokes(Stream.of(joke).collect(Collectors.toSet()));
}
}
userRepository.save(user);
return "Fav toggled successfully";
}
return "Unable to add fav. Invalid user or joke";
}
當前表內的信息如下:(笑話表有1k +行)
更新
根據評論中的建議添加了@@ JsonIdentityInfoannotation。 現在已經解決了堆棧溢出問題,但是信息的添加方式不正確。
這是我得到的JSON格式。
[{
"id": 5,
"question": "What is a gas station's favorite type of shoe?",
"answer": "Pumps.",
"users": [{
"memberId": 1,
"jokes": [5, {
"id": 7,
"question": "What kind of place should you never take a dog?",
"answer": "To the Flea Market.",
"users": [1],
"fav": false
}, {
"id": 8,
"question": "What do you call a cow in an earthquake?",
"answer": "A milkshake!",
"users": [1],
"fav": false
}, {
"id": 6,
"question": "Why was 6 afraid of 7?",
"answer": "Because 7 8 9!",
"users": [1],
"fav": false
}, {
"id": 4,
"question": "Why was Dracula put in jail?",
"answer": "He tried to rob a blood bank.",
"users": [1],
"fav": false
}]
}],
"fav": false
}, 7, 8, 6, 4]
奇怪的是,只有第一個笑話停留在最前面,其余的笑話一直被附加到上面的用戶列表中。
我期待以下內容(並計划排除內部用戶數據)。
[
{
"id": 6,
"question": "J1 What is a gas station's favorite type of shoe?",
"answer": "Pumps.",
"users": [{
"memberId": 1,
"jokes": [5]
}],
"fav": false
},
{
"id": 6,
"question": "J2 What is a gas station's favorite type of shoe?",
"answer": "Pumps.",
"users": [{
"memberId": 1,
"jokes": [6]
}],
"fav": false
},
{
"id": 7,
"question": "J3 What is a gas station's favorite type of shoe?",
"answer": "Pumps.",
"users": [{
"memberId": 1,
"jokes": [7]
}],
"fav": false
}
]
您可以使用@JsonIgnoreProperties
中斷周期:
public class Joke {
@JsonIgnoreProperties("jokes")
public Set<User> getUsers(){
return this.users;
}
}
如果獲得User,則可能會發生相同的問題,因此您可能還需要中斷User的周期:
public class User {
@JsonIgnoreProperties("users")
public Set<Joke> getJokes(){
return this.jokes;
}
}
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