Spring启动写入谓词以从给定的角色列表中检索用户

Question

我正在尝试创建一个谓词来检索具有特定角色列表的用户(角色是一个单独的表(我为User实体中的其他字段创建了谓词，但无法为上述场景创建正确的条件。以下是的两个实体类别

用户：

@Entity
@Table(name = "user")
@Data
public class User implements Serializable {
public User() {
}
public User(User user) {
this.username = user.getUsername();
this.password = user.getPassword();
this.email = user.getEmail();
this.fullName = user.getFullName();
this.address = user.getAddress();
this.contactNo = user.getContactNo();
this.enabled = user.isEnabled();
this.accountNonExpired = user.isAccountNonExpired();
this.credentialsNonExpired = user.isCredentialsNonExpired();
this.accountNonLocked = user.isAccountNonLocked();
this.roles = user.getRoles();
}
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "username")
private String username;
@Column(name = "fullName")
private String fullName;
@Column(name = "contactNo")
private String contactNo;
@Column(name = "address")
private String address;
@Column(name = "password")
private String password;
@Column(name = "email")
private String email;
@Column(name = "enabled")
private boolean enabled;
@Column(name = "accountNonExpired")
private boolean accountNonExpired;
@Column(name = "credentialsNonExpired")
private boolean credentialsNonExpired;
@Column(name = "accountNonLocked")
private boolean accountNonLocked;

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "role_user", joinColumns = {@JoinColumn(name = "user_id", referencedColumnName = "id")},
inverseJoinColumns = {
@JoinColumn(name = "role_id", referencedColumnName = "id")})
private List<Role> roles;
}

角色

@Entity
@Table(name = "role")
@Data
public class Role implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
@Column(name = "name")
private String name;
@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "permission_role", joinColumns = {
@JoinColumn(name = "role_id", referencedColumnName = "id")}, inverseJoinColumns = {
@JoinColumn(name = "permission_id", referencedColumnName = "id")})
private List<Permission> permissions;

}

我必须使用谓词别无选择。指导我如何编写一个谓词来获取给定角色列表的用户。

Answer 1

如果您引用Java 8谓词类：

Predicate<User> userPredicate = user -> user.getRoles().equals(roleListArg);

如果你想要一个更复杂的谓词：

Predicate<User> userPredicate = user -> { 
... your code here
};

在比较类似的List对象时要小心。应该更好地检查用户是否具有某些角色(user.getRoles((.contents(role((

如果您参考JPA规范：

public Specification<User> getUserByRoles(List<Role> roles) {
return (root, query, criteriaBuilder) => {
Join<Role, User> join = root.join("role");
//Return the condition you want to build, this is an example to get by role id
return criteriaBuilder.in(join.get(id), roles.get(0).getId());
}
}