Java 在 WHERE 子句中带有集合的 HQL
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HQL with a collection in the WHERE clause
提问by black sensei
I've been trying for the this whole a query who is officially giving me nightmares. The system is a user and contact management. So I have UserAccount, Contactand Phone.
我一直在尝试查询谁正式给我做噩梦。该系统是一个用户和联系人管理。所以我有UserAccount，Contact和Phone。
UserAccounthas a bidirectional one-to-many relationship with Contactand an unidirectional one on phone all mapped by a Set:
UserAccount与电话上的双向一对多关系Contact和单向关系都由 a 映射Set：
//UserAccount mapping
@OneToMany(targetEntity=PhoneImpl.class, cascade= {CascadeType.ALL})
@org.hibernate.annotations.Cascade(value=org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
private Set<Phone> phones = new HashSet<Phone>();
@OneToMany(targetEntity=ContactImpl.class, cascade={CascadeType.ALL}, mappedBy="userAccount")
@org.hibernate.annotations.Cascade(value=org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
private Set<Contact> contacts = new HashSet<Contact>();
Contact now has a one-to-many unidirectional with phones
Contact 现在有一对多单向与手机
@OneToMany(targetEntity=PhoneImpl.class, cascade={CascadeType.ALL})
private Set<Phone> phones = new HashSet<Phone>();
I'm writing a method to check the existence of the same number for the same contact of a particular user by the email unique field.
我正在编写一种方法，通过电子邮件唯一字段检查特定用户的同一联系人的相同号码是否存在。
I know I could have overridden the equalsand hashcodefor that but since phone in a entity mapped by set I don't know at this moment how to do that. So I wanted to provide a method to rather check for that uniqueness for me before each entry on the contact page
我知道我可以为此覆盖equals和hashcode，但是由于电话在由 set 映射的实体中，我现在不知道该怎么做。所以我想提供一种方法，而不是在联系页面上的每个条目之前检查我的唯一性
public boolean checkForExistingPhone(String userEmail, String formatedNumber) {
List<Contact> result = null;
Session sess = getDBSession().getSession();
String query = "select Contact ,cphones.formatedNumber from Contact c inner join Contact.phones cphones where c.UserAccount.email = :email and cphones.formatedNumber= :number";
// try {
result = (List<Contact>) sess.createQuery(query)
.setParameter("email", userEmail)
.setParameter("number", formatedNumber).list();
// } catch (HibernateException hibernateException) {
// logger.error("Error while fetching contacts of email " + userEmail + " Details:" + hibernateException.getMessage());
// }
if(result == null)
return false;
else
return true;
}
I keep on having this error:
我一直有这个错误：
org.hibernate.hql.ast.QuerySyntaxException: Contact is not mapped [select
cphones.formatedNumber from Contact c inner join Contact.phones cphones where
c.UserAccount.email = :email and cphones.formatedNumber= :number].
I can't really figure out what happens and first i don't know how to treat collections in HSQ.thanks for reading
我真的不知道会发生什么，首先我不知道如何处理 HSQ 中的集合。感谢阅读
采纳答案by Juha Syrj?l?
HQL query would be probably something along these lines:
HQL 查询可能是这样的：
select c from Contact c join c.phones cphones where c.userAccount.email = :email and cphones.formatedNumber = :number
Also you may want to handle results of query like this. The list()method returns always a list, never a null.
您也可能希望像这样处理查询结果。该列表（）方法返回总是一个列表，从来没有空。
return !result.isEmpty();
