条件-联接表上的where子句

Question

I have two tables in a MySQL database: COURSE and COURSE_SESSION.

COURSE has two fields : code(primary key) and title.

CourseSession has a field called course_code which is a foreign key linked to an element of Course.

I want to do somthing like this but using the Criteria API in Java :

SELECT * FROM COURSE_SESSION join COURSE 
WHERE course_code = code AND title like "%substring%";

Both tables are mapped correctly with hibernate.

I tried this :

Criteria criter = s.createCriteria(CourseSession.class);
        criter.add(Restrictions.like("courseCode.title", "%substring%"));

But I end up with an error :

HTTP 500 - could not resolve property: courseCode.title of: org.xxx.core.entity.CourseSession

message could not resolve property: courseCode.title of: org.xxx.core.entity.CourseSession

exception

org.hibernate.QueryException: could not resolve property: courseCode.title of: fr.utbm.lo54.core.entity.CourseSession
    org.hibernate.persister.entity.AbstractPropertyMapping.propertyException(AbstractPropertyMapping.java:81)
    org.hibernate.persister.entity.AbstractPropertyMapping.toColumns(AbstractPropertyMapping.java:96)
    org.hibernate.persister.entity.BasicEntityPropertyMapping.toColumns(BasicEntityPropertyMapping.java:62)
    org.hibernate.persister.entity.AbstractEntityPersister.toColumns(AbstractEntityPersister.java:1443)
    org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumns(CriteriaQueryTranslator.java:483)
    org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumnsUsingProjection(CriteriaQueryTranslator.java:443)
    org.hibernate.criterion.SimpleExpression.toSqlString(SimpleExpression.java:68)
    org.hibernate.loader.criteria.CriteriaQueryTranslator.getWhereCondition(CriteriaQueryTranslator.java:380)
    org.hibernate.loader.criteria.CriteriaJoinWalker.(CriteriaJoinWalker.java:114)
    org.hibernate.loader.criteria.CriteriaJoinWalker.(CriteriaJoinWalker.java:83)
    org.hibernate.loader.criteria.CriteriaLoader.(CriteriaLoader.java:92)
    org.hibernate.impl.SessionImpl.list(SessionImpl.java:1687)
    org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:347)
    fr.utbm.lo54.core.servlet.SearchData.doGet(SearchData.java:52)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

The strange thing is that if I do a Restriction on courseCode.code with Restrictions.like("courseCode.code", "%substring%") , it works fine.

EDIT

Course.hbm.xml :

<!DOCTYPE hibernate-mapping PUBLIC
      "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="org.xxx.core.entity">
    <class name="Course" table="COURSE">
        <id name="code" column="CODE">
            <generator class ="identity"/>
        </id>
    <property name="title" column="TITLE" not-null="true"/>
    </class>
</hibernate-mapping>

CourseSession.hbm.xml :

<!DOCTYPE hibernate-mapping PUBLIC
      "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="org.xxx.core.entity">
    <class name="CourseSession" table="COURSE_SESSION">
        <id name="id" column="ID">
            <generator class="identity" />
        </id>

        <property name="startDate" column="START_DATE" not-null="true" />
        <property name="endDate" column="END_DATE" not-null="true" />
        <many-to-one name="courseCode" column="COURSE_CODE" />
        <many-to-one name="locationId" column="LOCATION_ID" />
    </class>
</hibernate-mapping>

Answer 1

create an alias for the field first to achieve this.

try the below code, it should help

criter.createAlias("courseCode","courseCode");//course code is the association variable in your pojo class.