JPA concatenating table names for parent/child @OneToMany
jpa, openjpa
Solution
You may want to add a mappedBy attribute to the owning side of the relationship. This tells JPA that it is only one relatiuonship and not two different relationships. Maybe on the many side.
Problem
We are trying to use a basic @OneToMany relationship: ``` @Entity @Table(name = "PARENT_MESSAGE") public class ParentMessage { @Id @Column(name = "PARENT_ID") @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer parentId; @OneToMany(mappedBy="parentMsg",fetch=FetchType.LAZY) private List childMessages; public List getChildMessages() { return this.childMessages; } ... } @Entity @Table(name = "CHILD_MSG_USER_MAP") public class ChildMessage { @Id @Column(name = "CHILD_ID") @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer childId; @ManyToOne(optional=false,targetEntity=ParentMessage.class,cascade={CascadeType.REFRESH}, fetch=FetchType.LAZY) @JoinColumn(name="PARENT_ID") private ParentMessage parentMsg; public ParentMessage getParentMsg() { return parentMsg; } ... } ``` ``` ChildMessage child = new ChildMessage(); em.getTransaction().begin(); ParentMessage parentMessage = (ParentMessage) em.find(ParentMessage.class, parentId); child.setParentMsg(parentMessage); List list = parentMessage.getChildMessages(); if(list == null) list = new ArrayList<ChildMessage>(); list.add(child); em.getTransaction().commit(); ``` We receive the following error. Why is OpenJPA concatenating the table names to `APP.PARENT_MESSAGE_CHILD_MSG_USER_MAP`? Of course that table doesn't exist.. the tables defined are `APP.PARENT_MESSAGE` and `APP.CHILD_MSG_USER_MAP` Caused by: org.apache.openjpa.lib.jdbc.ReportingSQLException: Table/View 'APP.PARENT_MESSAGE_CHILD_MSG_USER_MAP' does not exist. {SELECT t1.CHILD_ID, t1.PARENT_ID, t1.CREATED_TIME, t1.USER_ID FROM APP.PARENT_MESSAGE_CHILD_MSG_USER_MAP t0 INNER JOIN APP.CHILD_MSG_USER_MAP t1 ON t0.CHILDMESSAGES_CHILD_ID = t1.CHILD_ID WHERE t0.PARENTMESSAGE_PARENT_ID = ?} [code=30000, state=42X05]