java 执行查询时ManyToMany关系不起作用(Spring Data JPA)

o7jaxewo 于 2023-11-15 发布在 Java

关注(0)|答案(5)|浏览(156)

我有一个UserEntity和一个RoleEntity。UserEntity包含一个字段“roles”，该字段的类型为HashSet，并使用@ManyToMany注解进行注解。当调用我的自定义查询“findByEmail”时，它成功地获取了UserEntity，但roles集保持为空。
下面是部分代码：
UserEntity.java

package xyz.michaeltprojects.collchecklist.security.persistence;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import javax.persistence.*;
import javax.validation.constraints.Email;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Size;
import java.util.HashSet;
import java.util.Set;
import java.util.UUID;

@Entity
@Table(name = "users")
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
public class UserEntity {

    @Id
    @GeneratedValue
    private UUID id;

    @NotBlank
    @Size(min = 3, max = 30)
    private String username;

    @NotBlank
    @Size(min = 6, max = 50)
    @Email
    private String email;

    @NotBlank
    @Size(max = 120)
    private String password;

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "user_roles", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "role_id"))
    private Set<RoleEntity> roles = new HashSet<>();

}

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RoleEntity.java

package xyz.michaeltprojects.collchecklist.security.persistence;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import javax.persistence.*;
import java.util.UUID;

@Entity
@Table(name = "roles")
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
public class RoleEntity {

    @Id
    @GeneratedValue
    private UUID id;

    @Enumerated(EnumType.STRING)
    @Column(length = 20)
    private ERole name;

}

型
UserRepository.java

package xyz.michaeltprojects.collchecklist.security.persistence;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import java.util.Optional;
import java.util.UUID;

@Repository
public interface UserRepository extends JpaRepository<UserEntity, UUID> {

    Optional<UserEntity> findByEmail(String email);
    Boolean existsByUsername(String username);
    Boolean existsByEmail(String email);

}

型

调用findByEmail方法时的输出

x1c 0d1x的数据

数据库表user_roles和roles

的

Java

来源：https://stackoverflow.com/questions/71511165/manytomany-relationship-not-working-when-executing-query-spring-data-jpa

5条答案

按热度按时间

tkqqtvp11#

我已经解决了这个问题.

赞(0）回复(0）举报 2023-11-15

70gysomp2#

你的ManyToMany不正确，你需要用referencedColumnName引用每个表的id
看看这个：

@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinTable(name = "user_roles",
     joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"),
     inverseJoinColumns = @JoinColumn(name = "role_id", referencedColumnName = "id"))
private Set<RoleEntity> roles;

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赞(0）回复(0）举报 2023-11-15

0g0grzrc3#

你能尝试一下吗？在UserEntity类下面添加一个覆盖函数setRoles（..）

package xyz.michaeltprojects.collchecklist.security.persistence;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;

import javax.persistence.*;
import javax.validation.constraints.Email;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.Size;
import java.util.HashSet;
import java.util.Set;
import java.util.UUID;

@Entity
@Table(name = "users")
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
public class UserEntity {

    @Id
    @GeneratedValue
    private UUID id;

    @NotBlank
    @Size(min = 3, max = 30)
    private String username;

    @NotBlank
    @Size(min = 6, max = 50)
    @Email
    private String email;

    @NotBlank
    @Size(max = 120)
    private String password;

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "user_roles", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "role_id"))
    private Set<RoleEntity> roles = new HashSet<>();

   public UserEntity setRoles(final Set<RoleEntity> roles) {
     this.roles.clear();
     if (roles != null) {
         this.roles.addAll(roles);
     }
     return this;
   }

}

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lokaqttq4#

您必须从用户实体中删除new HashSet<>();。

赞(0）回复(0）举报 2023-11-15

2w2cym1i5#

尝试使用List roles = new ArrayList<>()
在我的代码中，我使用了Set with ManyToMany关系，在我将Set改为List之后，我没有得到任何关联的值。我不明白为什么Set with hashSet不起作用。

赞(0）回复(0）举报 2023-11-15