[英]Distinct results from Spring Data JPA Specification that uses join
I have the following Specification
that I use to query for any Contact
entities that are tied to certain ManagedApplication
entities.我有以下
Specification
,用于查询与某些ManagedApplication
实体相关联的任何Contact
实体。 I pass in a Collection<Long>
that contains the ids of the ManagedApplication
entities that I am searching for.我传入一个
Collection<Long>
,其中包含我正在搜索的ManagedApplication
实体的 ID。
public static Specification<Contact> findByApp(final Collection<Long> appIds) {
return new Specification<Contact>() {
@Override
public Predicate toPredicate(Root<Contact> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
final Predicate appPredicate = root.join(Contact_.managedApplications)
.get(ManagedApplication_.managedApplicationId).in(appIds);
}
}
}
I pass this specification to the .findAll()
method of my PagingAndSoringRepository
to retrieve a Page<Contact>
that will contain all Contact
entities that meet the search criteria.我将此规范传递给我的
PagingAndSoringRepository
的.findAll()
方法以检索Page<Contact>
,其中将包含满足搜索条件的所有Contact
实体。
Here is the Repository
.这是
Repository
。
@Repository
public interface PagingAndSortingContactRepository extends PagingAndSortingRepository<Contact, Long>, JpaSpecificationExecutor<Contact> {
}
And here is how I'm calling the .findAll()
method.这是我调用
.findAll()
方法的方式。
final Page<Contact> contacts = pagingAndSortingContactRepository.findAll(ContactSpecification.findByApp(appIds), pageable);
This works and returns all Contact
entities that are tied to any of the ManagedApplication
entities that correspond to the ids passed in. However, since I am calling .join()
to join the Contact
entity with the ManagedApplication
entity, if one Contact
has multiple ManagedApplication
entities in the list of app ids, then the query will return duplicate Contact
entities.这有效并返回绑定到与传入的 id 相对应的任何
ManagedApplication
实体的所有Contact
实体。但是,由于我调用.join()
将Contact
实体与ManagedApplication
实体连接起来,如果一个Contact
有多个ManagedApplication
实体,则查询将返回重复的Contact
实体。
So what I need to know is, how can I get only distinct Contact
entities returned from my query using this Specification
?所以我需要知道的是,如何使用此
Specification
从我的查询中只获取不同的Contact
实体?
I know that CriteriaQuery
has a .distinct()
method that you can pass a boolean value to, but I am not using the CriteriaQuery
instance in the toPredicate()
method of my Specification
.我知道
CriteriaQuery
有一个.distinct()
方法,您可以将一个布尔值传递给它,但我没有在我的Specification
的toPredicate()
方法中使用CriteriaQuery
实例。
Here are the relevant sections of my metamodels.这是我的元模型的相关部分。
Contact_.java:联系人_.java:
@StaticMetamodel(Contact.class)
public class Contact_ {
public static volatile SingularAttribute<Contact, String> firstNm;
public static volatile SingularAttribute<Contact, String> lastNm;
public static volatile SingularAttribute<Contact, String> emailAddress;
public static volatile SetAttribute<Contact, ManagedApplication> managedApplications;
public static volatile SetAttribute<Contact, ContactToStructure> contactToStructures;
}
ManagedApplication_.java托管应用程序_.java
@StaticMetamodel(ManagedApplication.class)
public class ManagedApplication_ {
public static volatile SingularAttribute<ManagedApplication, Integer> managedApplicationId;
}
Use the query
parameter in your toPredicate
method to invoke the distinct method.在
toPredicate
方法中使用query
参数来调用不同的方法。
Sample below:示例如下:
public Predicate toPredicate(Root<Contact> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
final Predicate appPredicate = root.join(Contact_.managedApplications)
.get(ManagedApplication_.managedApplicationId).in(appIds);
query.distinct(true);
...
a new static method could be added可以添加一个新的静态方法
public static Specification<Object> distinct() {
return (root, query, cb) -> {
query.distinct(true);
return null;
};
}
where later you could add when creating your Specification稍后您可以在创建规范时添加
Specification.where(
YourStaticClassWhereYouCreatedTheUpperMethod.distinct().and(..))
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