JPA Criteria API：如何选择嵌套集合中的属性

发布于 2024-11-01 04:27:33 字数 335 浏览 4 评论 0原文

我有一个类 Customer 和 CustomerDependant 实体。 客户与其依赖者具有多对多的双向关系。我需要找到按姓名和附属姓名过滤的客户。

它在 JPQL 中做了类似的事情：

select c join fetch c.dependants d from Customer c where c.name like
'foo' and d.name like 'foo'

How I can do the same thing with JPA Criteria Queries?

原文

I have a class Customer and CustomerDependant entities. Customer has many to many bi-directional relationship with its dependents. I need to find customers filtering by name and dependent name.

It's done something like this in JPQL:

select c join fetch c.dependants d from Customer c where c.name like
'foo' and d.name like 'foo'

How I can do the same thing with JPA Criteria Queries?

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陈甜 2024-11-08 04:27:33

摘自 JPA 规范第 6.5.4 节

CriteriaQuery<Department> q = cb.createQuery(Department.class);
Root<Department> d = q.from(Department.class);
d.fetch(Department_.employees, JoinType.LEFT);
q.where(cb.equal(d.get(Department_.deptno), 1)).select(d);

此查询等效于以下 Java 持久性查询语言查询：

SELECT d
FROM Department d LEFT JOIN FETCH d.employees
WHERE d.deptno = 1

这是我在没有 fetch 的情况下执行的操作

CriteriaQuery<Department> q = cb.createQuery(Department.class);
Root<Department> dept = q.from(Department.class);
Join<Department,Employee> emp = d.join(Department_.employees);
q.where(cb.equal(emp.get(Employee_.name),"edalorzo"));

Fetch 是一种连接类型，所以我想您也可以尝试一下。

Taken from JPA Specification section 6.5.4

CriteriaQuery<Department> q = cb.createQuery(Department.class);
Root<Department> d = q.from(Department.class);
d.fetch(Department_.employees, JoinType.LEFT);
q.where(cb.equal(d.get(Department_.deptno), 1)).select(d);

This query is equivalent to the following Java Persistence query language query:

SELECT d
FROM Department d LEFT JOIN FETCH d.employees
WHERE d.deptno = 1

This is what I do it without fetch

CriteriaQuery<Department> q = cb.createQuery(Department.class);
Root<Department> dept = q.from(Department.class);
Join<Department,Employee> emp = d.join(Department_.employees);
q.where(cb.equal(emp.get(Employee_.name),"edalorzo"));

Fetch is a type of join, so I guess you could experiment with that too.

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