多列上的JPA Join

Question

我有实体User、Organization和GrantedRole。它们的关系是GrantedRole定义了用户在组织中的角色。这三个实体都从它们的超类继承了一个字段"id"（用@id注释）。组织没有引用GrantedRole或User，这些关系是单向的。

@Entity
@Table(name = "role_assignments", uniqueConstraints = @UniqueConstraint(columnNames = {
    "user_id", "organization_id" }))
public class GrantedRole extends DomainEntity implements GrantedAuthority {
    public static enum Role {
        ROLE_MODM_USER, ROLE_MODM_ORGADMIN, ROLE_MODM_ADMIN
    }
    private User user;
    private Role role;
    private Organization organization;
    public static enum Role {
        ROLE_MODM_USER, ROLE_MODM_ORGADMIN, ROLE_MODM_ADMIN
    }
    @ManyToOne
    @NotNull
    public User getUser() {
        return user;
    }
    @NotNull
    @Enumerated(EnumType.STRING)
    public Role getRole() {
        return role;
    }
    @ManyToOne
    public Organization getOrganization() {
        return organization;
    }
    // Some setters
}
@Entity
@Table(name = "modmUsers")
public class User extends DomainEntity implements UserDetails {
    // Some other fields
    private Set<GrantedRole> roles = new HashSet<GrantedRole>();
    private Set<Organization> organizations = new HashSet<Organization>();
    @OneToMany(fetch = FetchType.EAGER, mappedBy = "user")
    public Set<GrantedRole> getRoles() {
        return roles;
    }
    @ManyToMany(fetch = FetchType.EAGER)
    public Set<Organization> getOrganizations() {
        return organizations;
    }
    // Some setters
}

现在，我想使用JPACcriteria来查找用户具有角色role_MODM_ORGADMIN的组织。但是生成的查询联接在一列上，这会导致GrantedRole中的行重复，因为User.id在GrantedRole中不是唯一的，Organization.id也不是唯一的。两者的组合是唯一的。

我查找组织的代码：

public List<Organization> findOrganizationsByOrgAdminUser(String 
    CriteriaBuilder cb = entityManager.
    CriteriaQuery<Organization> query = cb.createQuery(Organization.
    Root<User> root = query.from(User.class);
    SetJoin<User, Organization> joinOrg = root.joinSet("organizations");
    SetJoin<User, GrantedRole> joinRoles = root.joinSet("roles");
    Predicate p1 = cb.equal(root.get("id"), userId);
    Predicate p2 = cb.equal(joinRoles.get("role"), Role.ROLE_MODM_ORGADMIN);
    query.select(joinOrg);
    query.where(cb.and(p1, p2));
    return entityManager.createQuery(query).getResultList();
}

生成的查询是：

SELECT
    orgs.* 
FROM
    modmUsers users
INNER JOIN
    modmUsers_organizations u_o 
        ON users.id=u_o.modmUsers_id 
INNER JOIN
    organizations orgs
        ON u_o.organization_id=orgs.id 
INNER JOIN
    role_assignments roles 
        ON users.id=roles.user_id 
WHERE
    users.id=? 
    and roles.role=?

我想要的查询是：

SELECT
    orgs.* 
FROM
    modmUsers users
INNER JOIN
    modmUsers_organizations u_o 
        ON users.id=u_o.modmUsers_id 
INNER JOIN
    organizations orgs
        ON u_o.organization_id=orgs.id 
INNER JOIN
    role_assignments roles 
        ON users.id=roles.user_id 
        AND orgs.id=roles.organization_id //how to do this???
WHERE
    users.id=? 
    and roles.role=?

Answer 1

好的，所以我的同事帮我解决了问题，并引导我进行以下查询：

SELECT
    orgs.* 
FROM
    modmUsers users
INNER JOIN
    modmUsers_organizations u_o 
        ON users.id=u_o.modmUsers_id 
INNER JOIN
    organizations orgs
        ON u_o.organization_id=orgs.id 
INNER JOIN
    role_assignments roles 
        ON users.id=roles.user_id 
WHERE
    users.id=? 
    AND roles.role=?
    AND orgs.id=roles.organization_id

这是我代码的一个简单扩展：

public List<Organization> findOrganizationsByOrgAdminUser(String 
    CriteriaBuilder cb = entityManager.
    CriteriaQuery<Organization> query = cb.createQuery(Organization.
    Root<User> root = query.from(User.class);
    SetJoin<User, Organization> joinOrg = root.joinSet("organizations");
    SetJoin<User, GrantedRole> joinRoles = root.joinSet("roles");
    Predicate p1 = cb.equal(root.get("id"), userId);
    Predicate p2 = cb.equal(joinRoles.get("role"), Role.ROLE_MODM_ORGADMIN);
    Predicate p3 = cb.equal(joinOrg.get("id"), joinRoles.get("organization"));
    query.select(joinOrg);
    query.where(cb.and(p1, p2, p3));
    return entityManager.createQuery(query).getResultList();
}