[jboss-user] [JBoss Seam] - Illegal use of mappedBy on both sides of the relationship: m

[irVega]

I have used seam-gen's generate-entities on a simple schema I knocked up (using HSQLDB), whilst I learn the basics of SEAM, with a view to prototype a system that will run against a legacy database.
There is a many-to-many relationship between 2 tables A (the auto-generated PK is ID_) and B (the auto-generated PK is ID_) which is resolved by C which just holds the ids of A and B (as A_ID and B_ID, both columns constrained by foreign key constraints on tables A and B repectively). The schema is included below. 
The generated entity A has a Set of Bs and the generated entity for B has a Set of As. All good.

When I deploy the app, using the generated ant script, I get 
Illegal use of mappedBy on both sides of the relationship: m2m.B.as
(where the "as" in "B.as" is the plural of a).

There's probably something going on under the covers as I can't see anything obvious in the generated source code (see below), possibly to do with cascading deletes (?). Is this a known condition of the reverse-engineering process for many to many relationships (possibly in Hibernate rather than seam-gen)? Is there some setting that needs to be set to avoid this?


The schema looks like this

  | CREATE MEMORY TABLE A(ID_ BIGINT GENERATED BY DEFAULT AS IDENTITY(START WITH 1) NOT NULL PRIMARY KEY)
  | CREATE MEMORY TABLE B(ID_ BIGINT GENERATED BY DEFAULT AS IDENTITY(START WITH 1) NOT NULL PRIMARY KEY)
  | CREATE MEMORY TABLE C(A_ID BIGINT NOT NULL,B_ID BIGINT NOT NULL,CONSTRAINT C_PK PRIMARY KEY(A_ID,B_ID),CONSTRAINT C_TO_A FOREIGN KEY(A_ID) REFERENCES A(ID_),CONSTRAINT C_TO_B FOREIGN KEY(B_ID) REFERENCES B(ID_))
  | 



The generated java source code:

A.java


  | package m2m;
  | // Generated 25-Mar-2007 18:15:55 by Hibernate Tools 3.2.0.b9
  | 
  | import java.util.HashSet;
  | import java.util.Set;
  | import javax.persistence.CascadeType;
  | import javax.persistence.Column;
  | import javax.persistence.Entity;
  | import javax.persistence.FetchType;
  | import javax.persistence.Id;
  | import javax.persistence.ManyToMany;
  | import javax.persistence.Table;
  | import org.hibernate.validator.NotNull;
  | 
  | /**
  |  * A generated by hbm2java
  |  */
  | @Entity
  | @Table(name = "A", schema = "PUBLIC")
  | public class A implements java.io.Serializable {
  | 
  | 	private long id;
  | 	private Set<B> bs = new HashSet<B>(0);
  | 
  | 	public A() {
  | 	}
  | 
  | 	public A(long id) {
  | 		this.id = id;
  | 	}
  | 	public A(long id, Set<B> bs) {
  | 		this.id = id;
  | 		this.bs = bs;
  | 	}
  | 
  | 	@Id
  | 	@Column(name = "ID_", unique = true, nullable = false)
  | 	@NotNull
  | 	public long getId() {
  | 		return this.id;
  | 	}
  | 
  | 	public void setId(long id) {
  | 		this.id = id;
  | 	}
  | 	@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "as")
  | 	public Set<B> getBs() {
  | 		return this.bs;
  | 	}
  | 
  | 	public void setBs(Set<B> bs) {
  | 		this.bs = bs;
  | 	}
  | 
  | }
  | 


B.java


  | 
  | package m2m;
  | // Generated 25-Mar-2007 18:15:55 by Hibernate Tools 3.2.0.b9
  | 
  | import java.util.HashSet;
  | import java.util.Set;
  | import javax.persistence.CascadeType;
  | import javax.persistence.Column;
  | import javax.persistence.Entity;
  | import javax.persistence.FetchType;
  | import javax.persistence.Id;
  | import javax.persistence.ManyToMany;
  | import javax.persistence.Table;
  | import org.hibernate.validator.NotNull;
  | 
  | /**
  |  * B generated by hbm2java
  |  */
  | @Entity
  | @Table(name = "B", schema = "PUBLIC")
  | public class B implements java.io.Serializable {
  | 
  | 	private long id;
  | 	private Set<A> as = new HashSet<A>(0);
  | 
  | 	public B() {
  | 	}
  | 
  | 	public B(long id) {
  | 		this.id = id;
  | 	}
  | 	public B(long id, Set<A> as) {
  | 		this.id = id;
  | 		this.as = as;
  | 	}
  | 
  | 	@Id
  | 	@Column(name = "ID_", unique = true, nullable = false)
  | 	@NotNull
  | 	public long getId() {
  | 		return this.id;
  | 	}
  | 
  | 	public void setId(long id) {
  | 		this.id = id;
  | 	}
  | 	@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "bs")
  | 	public Set<A> getAs() {
  | 		return this.as;
  | 	}
  | 
  | 	public void setAs(Set<A> as) {
  | 		this.as = as;
  | 	}
  | 
  | }
  | 

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