关于java：JPA Criteria builder IN子句查询


JPA Criteria builder IN clause query

如何为以下给定的JPQL查询编写条件构建器api查询？
我正在使用JPA 2.2。

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SELECT *
FROM Employee e
WHERE e.Parent IN ('John','Raj')
ORDER BY e.Parent

此标准设置应该可以解决问题：

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CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Employee> q = cb.createQuery(Employee.class);


Root<Employee> root = q.from(Employee.class);
q.select(root);

List<String> parentList = Arrays.asList(new String[]{"John","Raj"});

Expression<String> parentExpression = root.get(Employee_.Parent);
Predicate parentPredicate = parentExpression.in(parentList);
q.where(parentPredicate);
q.orderBy(cb.asc(root.get(Employee_.Parent));

q.getResultList();

我在这里使用了重载的CriteriaQuery.where方法，该方法接受Predicate ..在这种情况下是in谓词。

相关讨论

您还可以使用Criteria API In子句来执行此操作，如下所示：

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CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Employee> cq = cb.createQuery(Employee.class);
Root<Employee> root = cq.from(Employee.class);
List<String> parentList = Arrays.asList("John","Raj");
In<String> in = cb.in(root.get(Employee_parent));
parentList.forEach(p -> in.value(p));

return entityManager
        .createQuery(cq.select(root)
        .where(in).orderBy(cb.asc(root.get(Employee_.Parent)))
        .getResultList();

为此和几乎所有可能的标准示例签出我的Github。

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List<String> parentList = Arrays.asList("John","Raj");            
final CriteriaBuilder cb = entityManager.getCriteriaBuilder();
final CriteriaQuery<Employee> query = cb.createQuery(Employee.class);
final Root<Employee> employee = query.from(Employee.class);

query.select(employee).where(employee.get("Parent").in(parentList));

这应该工作正常。有关更多信息，请参阅baeldung的这篇文章。这是非常足智多谋的https://www.baeldung.com/jpa-criteria-api-in-expressions

我希望它会有用。在Entry只有一个@Id列的情况下测试了代码：

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public static <Entry, Id> List<Entry> getByIds(List<Id> ids, Class<Entry> clazz, EntityManager entityManager) throws CustomDatabaseException
{
    List<Entry> entries;
    try
    {
        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
        CriteriaQuery<Entry> q = cb.createQuery(clazz);
        Root<Entry> root = q.from(clazz);
        EntityType<Entry> e = root.getModel();
        CriteriaQuery<Entry> all = q.where(root.get(e.getId(e.getIdType().getJavaType()).getName()).in(ids));

        TypedQuery<Entry> allQuery = entityManager.createQuery(all);
        entries = allQuery.getResultList();
    }
    catch (NoResultException nre)
    {
        entries = Collections.emptyList()
    }
    catch (Exception e)
    {
        throw new CustomDatabaseException(e);
    }
    return entries;
}

当您需要使用Criteria API再次执行此操作时，请不要打断您-您可以为Dao创建一个父包装类，并在其中放置一个hepler方法：

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/**
  * An SQL"WHERE IN" expression alternative.
  *
  * @param inList List to search in.
  * @param pathToEntityField Path to a field in your entity object.
  * @return A ready predicate-condition to paste into CriteriaQuery.where().
  */
 @SuppressWarnings("unchecked")
 private Predicate in(List< ? > inList, Expression pathToEntityField) {

   return pathToEntityField.in(inList);
}

使用WHERE IN然后像这样：

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query.where(**in**(myList, root.get(MyTypedEntity_.id)));