QueryDsl - 集合表达式中的子查询

2022-01-18 00:00:00 spring java spring-data querydsl

我正在使用 spring-data-jpa 和 querydsl (3.2.3)
我有一个场景，我正在根据用户文件管理器/输入创建一组谓词.所有这些都来自 BooleanExpression.

I'm using spring-data-jpa and querydsl (3.2.3)
I have a scenario where I'm creating set of predicates based on user filer/input. All of these comes to BooleanExpression.

我的简化模型如下所示:

My simplified model looks as following: 

@Entity
public class Invoice {
    @ManyToOne
    private Supplier supplier;
}

@Entity
public class Supplier {
    private String number;
}

@Entity
public class Company {
    private String number;
    private boolean active
}

现在，我正在努力解决这个问题:

Now, what I'm struggling with is this query: 

SELECT * FROM Invoice WHERE invoice.supplier.number in (SELECT number from Company where active=true)

所以基本上我需要以 CollectionExpression 之类的格式进行子查询，该格式将获取所有公司编号并将其设置为 in() 表达式.

So basically I need to subquery in CollectionExpression like format that will fetch all companies numbers and sets this into in() expression.

我的 spring-data 存储库实现了 CustomQueryDslJpaRepository，后者又扩展了 JpaRepository 和 QueryDslPredicateExecutor.
我希望这个问题的答案是直截了当的，但我对 querydsl 很陌生，到目前为止还没有找到解决方案.

My spring-data repositories implements CustomQueryDslJpaRepository which in turn extends JpaRepository and QueryDslPredicateExecutor.
I hope the answer to this is straightforward, but I'm quite new to querydsl and didn't find the solutions so far.

推荐答案

这里是 jaiwo99 答案的变体，更 JPAesque 形式

Here is a variant of jaiwo99's answer in a more JPAesque form

BooleanExpression exp = invoice.supplier.number.in(new JPASubQuery()
    .from(company)
    .where(company.active.isTrue())
    .list(company.nu‌​mber));

请随意将其合并到原始答案中.

Feel free to merge this into the original answer.

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