如何在 JPA Criteria API 上正确使用 JOIN

Posted 2023-02-24

【中文标题】如何在 JPA Criteria API 上正确使用 JOIN

【英文标题】：How to proper use JOIN on JPA Criteria API

【发布时间】：2021-12-22 19:50:08

【问题描述】：

我正在尝试使用 Criteria API 进行动态过滤和 SQL 调节。我的过滤正在工作，但不能执行 join 子句。 这是我的 filter&join 方法。

public Page<ReceivedFax> findAllWithFilters(PageRequest pageRequest,
                                            Map<String, String> receivedFaxSearchCriteriaMap, String uuid) 

    CriteriaQuery<ReceivedFax> criteriaQuery = criteriaBuilder.createQuery(ReceivedFax.class);

    Root<ReceivedFax> receivedFaxRoot = criteriaQuery.from(ReceivedFax.class);
    
    Join<ReceivedFax, Account> join = receivedFaxRoot.join("account");
    join.on(criteriaBuilder.equal(join.get("uuid"), uuid));
    criteriaQuery.multiselect(join);

    Predicate predicate = getPredicate(receivedFaxSearchCriteriaMap, receivedFaxRoot);
    criteriaQuery.where(predicate);
    TypedQuery<ReceivedFax> typedQuery = entityManager.createQuery(criteriaQuery);
    typedQuery.setFirstResult(pageRequest.getPageNumber() * pageRequest.getPageSize());
    typedQuery.setMaxResults(pageRequest.getPageSize());

    long receivedFaxCount = getReceivedFaxCount(predicate);

    return new PageImpl<>(typedQuery.getResultList(), pageRequest, receivedFaxCount);

我需要使用这个 SQL：

select *
from ReceivedFaxes
         join Accounts A on A.ID = ReceivedFaxes.AccountID
where A.UUID = '522f6084-893f-4063-92d1-b9130fc88400'(uuid);

我收到此错误：

"org.hibernate.hql.internal.ast.QuerySyntaxException: 
 Unable to locate appropriate constructor on class [model.receivedfax.ReceivedFax]. 
Expected arguments are: model.account.Account [
  select new model.receivedfax.ReceivedFax(generatedAlias0) 
  from model.receivedfax.ReceivedFax as generatedAlias1 
  inner join generatedAlias1.account as generatedAlias0 
  with generatedAlias0.uuid=:param0 where 1=1]; 
nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: 
 Unable to locate appropriate constructor on class [model.receivedfax.ReceivedFax].
 Expected arguments are: model.account.Account [
  select new model.receivedfax.ReceivedFax(generatedAlias0) 
  from model.receivedfax.ReceivedFax as generatedAlias1 
  inner join generatedAlias1.account as generatedAlias0 
  with generatedAlias0.uuid=:param0 where 1=1]"

【问题讨论】：

你想用这条线做什么？ criteriaQuery.multiselect(join);多选是投影

我正在尝试将 Account Entity 加入 ReceivedFax 实体，然后给出 WHERE 子句进行调节。

然后简单地删除 criteriaQuery.multiselect(join);

【参考方案1】：

正如西蒙所说，这是我的错。删除后 criteriaQuery.multiselect(join) Criteria API 正在正常工作。