Question

我对hibernate相当新，目前正在使用标准触发查询。

我想要实现的是，在first或lastname列中选择包含特定字符串的所有记录。

这就是我所拥有的。它应该提供一个更好的主意。

Session session = HibernateUtil.openSession();
    Criteria criteria = session.createCriteria(Contact.class);

    if(keywords != null) {
        for(String keyword : keywords) {
            if(keyword != null && keyword.length() > 0) {
                criteria.add(Restrictions.like("firstName", keyword, MatchMode.ANYWHERE));
                criteria.add(Restrictions.or(Restrictions.like("lastName", keyword, MatchMode.ANYWHERE), null));
            }
        }
    }

    searchMatches = criteria.list();

所以最后查询应该是：

SELECT * FROM contacts WHERE（firstname LIKE'％oe％OR lastname LIKE'％oe％'），如果给出了多个关键字，则类似：

SELECT * FROM contacts WHERE（firstname LIKE'％oe％OR lastname LIKE'％oe％'）OR（firstname LIKE'％roo％OR lastname LIKE'％roo％'）

这将在first或lastname列中选择包含“oe”的记录。当criteria.list（）时，我怎么会遇到代码崩溃？运行。

这是堆栈跟踪。我无法弄清楚我做错了什么。

Caused by: java.lang.NullPointerException
at org.hibernate.criterion.LogicalExpression.toSqlString(LogicalExpression.java:60)
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getWhereCondition(CriteriaQueryTranslator.java:419)
at org.hibernate.loader.criteria.CriteriaJoinWalker.<init>(CriteriaJoinWalker.java:123)
at org.hibernate.loader.criteria.CriteriaJoinWalker.<init>(CriteriaJoinWalker.java:92)
at org.hibernate.loader.criteria.CriteriaLoader.<init>(CriteriaLoader.java:93)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1464)
at org.hibernate.internal.CriteriaImpl.list(CriteriaImpl.java:374)
at com.joey.wishlist.dao.impl.ContactDAOImpl.searchContacts(ContactDAOImpl.java:34)
at com.joey.wishlist.services.impl.ContactServiceImpl.searchContacts(ContactServiceImpl.java:22)
at com.joey.wishlist.presenters.ContactSearchPresenter.search(ContactSearchPresenter.java:75)

编辑：我离我更近了一步。

我修正了错误。错误是由故障引起的。

现在代码如下：

        if(keywords != null) {
        for(String keyword : keywords) {
            if(keyword != null && keyword.length() > 0) {
                criteria.add(
                        Restrictions.or(
                            Restrictions.like("lastName", keyword, MatchMode.ANYWHERE), 
                            Restrictions.like("firstName", keyword, MatchMode.ANYWHERE)
                        ));
            }
        }
    }

哪个产生这个查询，这几乎是我想要的。我只想让“AND”成为“OR”。所以：

Hibernate: 
/* criteria query */ select
    this_.id as id0_0_,
    this_.firstname as firstname0_0_,
    this_.lastname as lastname0_0_ 
from
    contactmanager this_ 
where
    (
        this_.lastname like ? 
        or this_.firstname like ?
    ) 
    and (
        this_.lastname like ? 
        or this_.firstname like ?
    )

我想成为：

Hibernate: 
/* criteria query */ select
    this_.id as id0_0_,
    this_.firstname as firstname0_0_,
    this_.lastname as lastname0_0_ 
from
    contactmanager this_ 
where
    (
        this_.lastname like ? 
        or this_.firstname like ?
    ) 
    or ( //Notice difference here
        this_.lastname like ? 
        or this_.firstname like ?
    )

Answer 1

每次拨打criteria.add时，都会在您的对帐单中添加and。你想要创造一个分离：

Disjunction matchDisjunction = Restrictions.disjunction()
for(String keyword : keywords) {
            if(keyword != null && keyword.length() > 0) {
                matchDisjunction.add(
                        Restrictions.or(
                            Restrictions.like("lastName", keyword, MatchMode.ANYWHERE), 
                            Restrictions.like("firstName", keyword, MatchMode.ANYWHERE)
                        ));
            }
        }
criteria.add(matchDisjunction);

或者简单地说：

Disjunction matchDisjunction = Restrictions.disjunction()
for(String keyword : keywords) {
            if(keyword != null && keyword.length() > 0) {
                matchDisjunction.add( Restrictions.like("lastName", keyword, MatchMode.ANYWHERE) );
                matchDisjunction.add( Restrictions.like("firstName", keyword, MatchMode.ANYWHERE) );
            }
        }
criteria.add(matchDisjunction);

具有可变数量的OR LIKE子句的Hibernate标准

1 个答案: