List 从CriteriaQuery获取列表时出现异常
由于某些原因，我无法判断，当我尝试使用子查询从CriteriaQuery获取列表时出现异常。有人请帮忙！！！ 代码如下：List 从CriteriaQuery获取列表时出现异常,list,exception,subquery,criteria-api,criteriaquery,List,Exception,Subquery,Criteria Api,Criteriaquery,由于某些原因，我无法判断，当我尝试使用子查询从CriteriaQuery获取列表时出现异常。有人请帮忙！！！ 代码如下： public String[] getProductsDistinctBySubQueriesName(String category) { CriteriaBuilder builder = em.getCriteriaBuilder(); CriteriaQuery<Tuple> criteria = builder.createTupleQu
public String[] getProductsDistinctBySubQueriesName(String category) {
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<Tuple> criteria = builder.createTupleQuery();
//subquery
Subquery<Integer> subqueries = criteria.subquery(Integer.class);
Root<Productscategory> productCategory = subqueries.from(Productscategory.class);
subqueries.select(productCategory.<Integer>get("productscategoryid"))
.where(builder.equal((productCategory.<String>get("productcatgoryname")), category));
//outerquery
Root<Products> root = criteria.from(Products.class);
criteria.multiselect(root.get(Products_.productname)).distinct(true)
.where(builder.in(root.get("productscategoryid")).value(subqueries));
List<Tuple> tupleResult = em.createQuery(criteria).getResultList(); // the exception is thrown here
String[] arrayProducts = new String[tupleResult.size()];
for (int i = 0; i < tupleResult.size(); i++) {
arrayProducts[i] = (String) tupleResult.get(i).get(0);
}
return arrayProducts;
}
... 24更多尝试使用此查询而不是您的查询，这与EclipseLink提供程序完美配合，不确定您的查询在EclipseLink中不起作用，但在hibernate中起作用，我测试了下面的查询，您将能够基于ProductCategoryName选择产品
EntityManagerFactory emf = Persistence.createEntityManagerFactory("jpaQuery");
EntityManager em = emf.createEntityManager();
String category = "cat2";
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<Products> query = builder.createQuery(Products.class);
Root<Products> products = query.from(Products.class);
Subquery<Productscategory> squery = query.subquery(Productscategory.class);
Root<Productscategory> productCategoryRoot = squery.from(Productscategory.class);
Join<Productscategory, Products> join = productCategoryRoot.join("productsCollection");
squery.select(productCategoryRoot)
.where(builder.equal(join, products), builder.equal(productCategoryRoot.get("productcatgoryname"), category));
query.where( builder.exists(squery));
List<Products> productList = em.createQuery(query).getResultList();
for (Products product : productList) {
System.out.println(product);
}
这就解决了问题。。如果这有效，不要忘记接受答案XD。它有效！！！你挽救了这一天！非常感谢。这是多么令人难忘的经历啊。再次感谢您！当我设置distincttrue时，我似乎无法得到不同的值。奇怪的