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@ManytoMany with JoinTable:Hibernate creating its own table

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sarmahdi

Post subject: @ManytoMany with JoinTable:Hibernate creating its own table

Posted: Thu Jan 20, 2011 6:26 am

Newbie

Joined: Sat Jan 01, 2011 4:31 am
Posts: 6

Hi All,
I am using Seam and hibernate and JPA. I am using Seam's EntityHome and EntityQuery classes to do the CRUD operations.
I have a question:
I have two entities with @Entity of JPA API.

I have created two lists of these two entities in each other and annotated like this:

Code:

@Table(name="CLASSA")
Class A{
@Id @GeneratedValue
   @Column(name="CLASSA_ID")
 private Long id;

@ManyToMany(cascade=CascadeType.PERSIST)
   @JoinTable(name="CLSA_CLSB",
    joinColumns = {
       @JoinColumn(name = "CLASSA_ID")},
    inverseJoinColumns = {
       @JoinColumn(name = "QID")})
 private List<ClassB> classesB= new ArrayList<ClassB>();
}

AND

Code:

@Table(name="CLASSB")
ClassB{
@Id @GeneratedValue
   @Column(name="QID")
    private Long id;
 @ManyToMany
    private List<ClassA> classesA;
}
 

I created the tables myself so instead of naming the jointable as : CLASSA_CLASSB i just named it CLSA_CLSB to keep it short

now the DB is already created, and when I deploy the application on JBOSS hibernate throws an exception that it is missing table: CLASSA_CLASSB,

why is it looking for CLASSA_CLASSB when I have already defined a JOINTABLE. now when i run this on an empty DB with

Code:

it does create the CLSA_CLSB with two fields as in the @MANYTOMANY annotation as well but it also throws an error that CLASSA_CLASSB cannot be created as Identifier (originally the CLASSA and CLASSB are appended with application name so it concatenates both table names which becoems tooo long).

i created the tables with create and then changed the value of the hibernate property to "Update" and I could work and the deployment was successful, BUT when i tried to REMOVE ClassB instances (I was able to create ClassB instances and store them in DB and update them ) it threw me the same error that it cannot find the CLASS_CLASSB table

why is it stuck on this table. why is it even trying to create it in the first place when i have already defined a JOINTABLE. If i keep the property of the hibernate as "validate" then it tries to find the CLASS_CLASSB table which I didnt make nor did i refer it anywhere.

I will really appreciate your help.

Thanks
Syed...

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Konsumierer

Post subject: Re: @ManytoMany with JoinTable:Hibernate creating its own table

Posted: Thu Jan 20, 2011 6:58 am

Newbie

Joined: Fri May 25, 2007 4:37 am
Posts: 13
Location: Germany

Try

Code:

@Table(name="CLASSA")
ClassA{
@Id @GeneratedValue
@Column(name="CLASSA_ID")
 private Long id;

@ManyToMany( cascade={CascadeType.PERSIST, CascadeType.MERGE},
            targetEntity=ClassB.class,)
@JoinTable(name="CLSA_CLSB",
    joinColumns = {
       @JoinColumn(name = "CLASSA_ID")},
    inverseJoinColumns = {
       @JoinColumn(name = "QID")})
 private List<ClassB> classesB= new ArrayList<ClassB>();
}

and

Code:

@Table(name="CLASSB")
ClassB{
@Id @GeneratedValue
@Column(name="QID")
private Long id;

@ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE},
        mappedBy = "classesB",
        targetEntity = ClassA.class)
private List<ClassA> classesA;
}
 

See: 2.2.5.3.2. Many-to-many in http://docs.jboss.org/hibernate/stable/ ... ml_single/

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sarmahdi

Post subject: Re: @ManytoMany with JoinTable:Hibernate creating its own table

Posted: Sat Jan 22, 2011 1:23 am

Newbie

Joined: Sat Jan 01, 2011 4:31 am
Posts: 6

Hi all,

Well for now i have removed the bidirectional and made it only uni directional so i have the manytomany on the classA only.

and now its not looking for that table. its working now. but i havent tested it on concrete data to check th relationship perfectly but I am sure it will work.

Thanks for your help..

Syed

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sarmahdi

Post subject: Re: @ManytoMany with JoinTable:Hibernate creating its own table

Posted: Tue Jan 25, 2011 1:44 am

Newbie

Joined: Sat Jan 01, 2011 4:31 am
Posts: 6

Ok the @ManyToMany on

Code:

@ManyToMany(cascade=CascadeType.PERSIST)
   @JoinTable(name="CLSA_CLSB",
    joinColumns = {
       @JoinColumn(name = "CLASSA_ID")},
    inverseJoinColumns = {
       @JoinColumn(name = "QID")})
private List<ClassB> classesB= new ArrayList<ClassB>();

and that was it...
actually it was the bidirectional which was causing problems.. It was detecting one table for one directional relationship but for the other directional (on Class_B ) there was no table mapped so it made a new one for that as well.

so that what I did . removed the @manyToMany from the classB and that was it.

Thank for the reply "Konsumierer" really appreciate your help.

Sar

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