Question

我与国家和人有1到M的关联。意思是一个国家可以有多个人。 country.hbm.xml文件如下所示：

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.test.hibernate">
  <class name="Country">
  <id name="countryId" column="CountryID" > </id>
  <property name="countryName" column="CountryName" length="50"></property>
  <set name="persons" table="Person" fetch="select" inverse="true">
  <key>
    <column name="CountryId" not-null="true"></column>
  </key> 
   <one-to-many class="com.test.hibernate.Person"/>     
  </set>
  </class>
</hibernate-mapping>

Person.hbm.xml如下所示

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.test.hibernate">
  <class name="Person">
    <id name="personID" column="PersonID" > </id>
    <property name="name" column="Name" length="50"></property>
    <property name="age" column="Age"></property>
    <property name="gender" column="Gender" length="1"></property>
    <property name="email" column="Email" length="50"></property>
    <property name="countryID" column="CountryID" insert="false" update="false"></property>

    <many-to-one name="Country" class="com.test.hibernate.Country" fetch="select">
        <column name="CountryID" not-null="true"></column>
    </many-to-one> 
  </class>
</hibernate-mapping>

现在，我正在尝试查询所有属于印度国家的男性

Criteria countryCriteria = session.createCriteria(Country.class);
Criterion country = Restrictions.eq("countryName", "India");
Criterion male = Restrictions.eq("persons.gender", "M");
countryCriteria.add(country);
countryCriteria.add(male);
List<Country> countryList = countryCriteria.list();

我得到了线程＆＃34; main＆＃34;中的例外情况org.hibernate.QueryException：无法解析属性：persons.gender：com.test.hibernate.Country 在org.hibernate.persister.entity.AbstractPropertyMapping.propertyException（AbstractPropertyMapping.java:83）在org.hibernate.persister.entity.AbstractPropertyMapping.toColumns（AbstractPropertyMapping.java:98）在org.hibernate.persister.entity.BasicEntityPropertyMapping.toColumns（BasicEntityPropertyMapping.java:61）在org.hibernate.persister.entity.AbstractEntityPersister.toColumns（AbstractEntityPersister.java:1960）在org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumns（CriteriaQueryTranslator.java:523）在org.hibernate.loader.criteria.CriteriaQueryTranslator.findColumns（CriteriaQueryTranslator.java:538）在org.hibernate.criterion.SimpleExpression.toSqlString（SimpleExpression.java:66）在org.hibernate.loader.criteria.CriteriaQueryTranslator.getWhereCondition（CriteriaQueryTranslator.java:419）在org.hibernate.loader.criteria.CriteriaJoinWalker。（CriteriaJoinWalker.java:123）在org.hibernate.loader.criteria.CriteriaJoinWalker。（CriteriaJoinWalker.java:92）在org.hibernate.loader.criteria.CriteriaLoader。（CriteriaLoader.java:95）在org.hibernate.internal.SessionImpl.list（SessionImpl.java:1643）在org.hibernate.internal.CriteriaImpl.list（CriteriaImpl.java:374）在com.test.hibernate.Main.main（Main.java:54）

请帮忙。我是Hibernate的新手。

提前致谢。

Answer 1

Country.persons的类型为Collection<Person>。 Collection没有任何名为“gender”的属性。

如果您使用HQL而不是Criteria（对于这样一个简单的静态查询，您应该使用HQL），则必须进行连接：

select c from Country c 
join country.persons person
where c.countryName = 'India' 
and person.gender = 'M'

因此，您必须对Criteria查询执行相同的操作：

Criteria countryCriteria = session.createCriteria(Country.class, "c");
countryCriteria.createALias("c.persons", "person");
countryCriteria.add(Restrictions.eq("c.countryName", "India"));
countryCriteria.add(Restrictions.eq("person.gender", "M"));
List<Country> countryList = countryCriteria.list();

Answer 2

我使用M来1并使用Criteria on Person对象而不是Country Object。

Criteria personCriteria = session.createCriteria(Person.class,"p");
personCriteria.createAlias("p.Country", "c");    
Criterion gender = Restrictions.eq("gender", "M");
Criterion country = Restrictions.eq("c.countryName", "India");
personCriteria.add(gender);
personCriteria.add(country);
List<Person> personList = personCriteria.list();

这样，personList拥有所有男性并属于印度的人。

对孩子进行Hibernate 1到M限制

2 个答案: