执行查询时多对多关系不起作用（Spring Data JPA）

Question

我有一个 UserEntity 和一个 RoleEntity。 UserEntity 包含一个字段“roles”，它是 HashSet 类型并使用 @ManyToMany 注释进行注释。 当调用我的自定义查询“findByEmail”时，它成功获取了 UserEntity，但角色集保持为空。

这里的代码的一些部分：

用户实体.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<>();

}

角色实体.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;

}

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);

}

调用 findByEmail 方法时调试 Output

数据库表“user_roles”和“roles”

Answer 1

我已经以某种方式解决了这个问题......似乎填充关系不适用于 UUID 作为标识符。 当我用多头替换它们时，它工作得很好。 看起来很奇怪，但它就像是

Answer 2

你ManyToMany不正确，你需要使用referencedColumnName来引用每个表的 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;

Answer 3

你能试试这个吗？ 通过在 UserEntity 类下面添加覆盖 function 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;
   }

}

Answer 4

你必须删除new HashSet<>(); 来自用户实体。