与QueryDSL的多个联接

Question

我试图将QueryDSL与Spring Data JPA一起使用。

@Entity
Account{
//...Other fields ommited
// **
@OneToMany
@JoinColumn(name = "ACCNT_NUMBER")
List<PersonRole> personRoles;**
}

@Entity
PersonRole{
String role;
// ...Other fields ommited
// **
@OneToOne
@JoinColumn(name = "PERSON_ID")
Person person;**
}


@Entity
Person{...}

    QAccount account = QAccount.account;
    QPersonRole personRoles = QPersonRole.personRole;
    QPerson person = QPerson.person;

    JPAQuery<Account> query = new JPAQuery<>(entityManager);

    List<Account> accountList = query
            .from(account)
            .innerJoin(acccount.personRoles, personRoles)
            .innerJoin(person)
            .where(person.lastName.eq("John")
                    .and(person.lastName.eq("Doe")))
            .fetch();

Answer 1

只有当你想从一个到多个过滤时才需要联接...jpql仍然可以被利用...我更喜欢在personRole上使用单数，所以：

QAccount account = QAccount.account;
QPersonRole personRole = QPersonRole.personRole;

JPAQuery<Account> query = new JPAQuery<>(entityManager);

List<Account> accountList = query
            .from(account)
            .innerJoin(acccount.personRoles, personRole)
            .where(personRole.person.lastName.eq("John")
                    .and(personRole.person.lastName.eq("Doe")))
            .fetch();

请注意如何不需要连接到Person。