One to Many Relationship liferay

• In Real life Student can assign to multiple course. Here we see example of One to Many where student can assign to many courses.

Create service in portlet.

• Add below content in your portlet service.  

<entity name="Student" local-service="true" remote-service="true" cache-enabled="false">
    <column name="studentId" type="long" primary="true" />
    <column name="courses" type="Collection" entity="Course"/>
</entity>

<entity name="Course" local-service="true" remote-service="true" cache-enabled="false">
 
<column name="courseId" type="long" primary="true" />
   <column name="studentId" type="long"/>

    <finder name="courseId" return-type="Collection">
        <finder-column name="courseId" />
    </finder>

    <finder name="studentId" return-type="Collection">
        <finder-column name="studentId" />
    </finder>

</entity>

• Run service.

• Now add below method in CourseLocalServiceImpl to make to finder mehod in publicly available with help of CourseLocalServiceUtil.

  public List<Course> getCourseForStudent(Long studentId) throws SystemException{
               return this.coursePersistence.findBystudentId(studentId);
}

• Now Again run Service.

• The method will available in CourseLocalServiceUtil which can use anywhere in your portlet.