EJB3 QL problem

jactor · **Joined:** Sun Aug 13, 2006 8:40 am **Posts:** 28

Hi I am using EJB QL and have the embedden version of Hibernate which is released with jboss-4.0.4.GA and am experiencing a query problrm which I cannot find a solution for. This is probably not an error, but my lack of knowledge in EJB QL.

I am trying to do this:
I have an entity (UserDescription) which have an instance of another entity (Role) with the data field 'name'. I am trying to get all instances of a UserDescription having a role named 'administrator', but I get an exception telling me that it can not resolve the property 'name'...

I am sorry for using the forum for this, but I do not where to turn... Can anyone help me?

Exception that occurs:

Code:

javax.ejb.EJBException: javax.persistence.PersistenceException: org.hibernate.QueryException: could not resolve property: name of: a.package.UserDescription [from a.package.UserDescription as ud fetch all properties where ( (ud.licenseHolderID = 0) ) and (ud.role.name = 'administrator')]

Debug level Hibernate log excerpt:

Code:

2006-08-13 14:31:33,703 DEBUG [org.hibernate.hql.ast.AST -  84] --- HQL AST ---
 \-[QUERY] 'query'
    +-[SELECT_FROM] 'SELECT_FROM'
    |  \-[FROM] 'from'
    |     \-[RANGE] 'RANGE'
    |        +-[DOT] '.'
    |        |  +-[DOT] '.'
    |        |  |  +-[DOT] '.'
    |        |  |  +-[IDENT] 'a'
    |        |  |  \-[IDENT] 'package'
    |        |  \-[IDENT] 'UserDescription'
    |        +-[ALIAS] 'ud'
    |        \-[FETCH] 'fetch'
    \-[WHERE] 'where'
       \-[AND] 'and'
          +-[EQ] '='
          |  +-[DOT] '.'
          |  |  +-[IDENT] 'udd'
          |  |  \-[IDENT] 'myLicenseHolderID'
          |  \-[NUM_INT] '0'
          \-[EQ] '='
             +-[DOT] '.'
             |  +-[DOT] '.'
             |  |  +-[IDENT] 'ud'
             |  |  \-[IDENT] 'role'
             |  \-[IDENT] 'name'
             \-[QUOTED_STRING] ''administrator''

Hibernate version:
The default released version in JBoss Application Server 4.0.4.GA

Name and version of the database you are using:
Hypersonic SQL which is embedden in the JBoss release.

hlfsousa · **Posted:** Mon Aug 14, 2006 9:44 am

Can you post the mapping (annotations and/or xml) for the UserDescription-Role association?

jactor · **Joined:** Sun Aug 13, 2006 8:40 am **Posts:** 28

there are no annotations for the association.

hlfsousa · **Posted:** Tue Aug 15, 2006 8:32 am

Then at least a code snippet that stablishes the relation between UserDescription and Role

jactor · **Joined:** Sun Aug 13, 2006 8:40 am **Posts:** 28

I thought a simple variable in an entity was a one to one relation by default. In the UserDescription it is:

Code:

Role role = null;

... and with getters and setters accordingly. The access of the data in the bean is by variable and not by getters and setters

hlfsousa · **Posted:** Wed Aug 16, 2006 9:05 am

A property like that could be either one-to-one or many-to-one, so you should sign which one you desire:

Code:

Role role;

@javax.persistence.ManyToOne
public Role getRole() {
    return role;
}
public void setRole(Role role) {
    this.role = role;
}

And if you want the other side to reversely map the relation too...

Code:

@OneToMany(mappedBy = "role")
public Set<UserDescription> getUserDescriptions() {
    /* the usual accessor, field and modifier */
}

jactor · **Joined:** Sun Aug 13, 2006 8:40 am **Posts:** 28

hlfsousa wrote:

A property like that could be either one-to-one or many-to-one, so you should sign which one you desire:

Code:

Role role;

@javax.persistence.ManyToOne
public Role getRole() {
    return role;
}
public void setRole(Role role) {
    this.role = role;
}

And if you want the other side to reversely map the relation too...

Code:

@OneToMany(mappedBy = "role")
public Set<UserDescription> getUserDescriptions() {
    /* the usual accessor, field and modifier */
}

... but do you need to have the annotation? ...and what purpose has the mappedBy parameter to the annotation?

... and I am probably wrong when I say one to one as default. I ment one to many, which is to say that a user description can have a role and another description may have the same role...

jactor · **Joined:** Sun Aug 13, 2006 8:40 am **Posts:** 28

I had 3 weeks of vacation and hoped that this issue was solved when I returned, but it is not so simple...

Please help!

To summarize; I am trying to do this:
I have an entity (UserDescription) which have an instance of another entity (Role) with the data field 'name'. I am trying to get all instances of a UserDescription having a role named 'administrator', but I get an exception telling me that it can not resolve the property 'name'...

The instance of Role (Role is an entity bean) is a variable in the entity UserDescription and does not have any special annotation.

jactor · **Joined:** Sun Aug 13, 2006 8:40 am **Posts:** 28

...and here is my original query which is producing the exception:

Code:

from a.package.UserDescription as ud where  ( (ud.licenseHolderID = 0) ) and (ud.role.id in (select r.id from another.package.Role as r where r.name = 'administrator'))

assaf27 · **Joined:** Sun Jan 22, 2006 6:56 am **Posts:** 29

Why do you think that the property should be annotated? Hibernate needs to know the mapping between classes, either by *.hbm.xml mapping files or by annotations. Using annotations there simple properties are mapped by default (assuming you've annotated the class with @Entity), but associations require extra information.

jactor · **Joined:** Sun Aug 13, 2006 8:40 am **Posts:** 28

I thought that properties of entity beans defaulted to the ManyToOne relation, but this is probably wrong as it is not working. However; Just stating @ManyToOne produce the same exception.

I also redesigned the query as it is not the role.id (every entity has a primary key (Long) which is generated) which is stated in the database but 'B@184b649' which seems to be a memory referance or something. Maybe this is because the relation is not stated...

The query (but it still produce the same type of exception stating that role is not mapped):

Code:

from a.package.UserDescription as ud where  ( (ud.licenseHolderID = 0) ) and (ud.role in (select r from another.package.Role as r where r.name = 'administrator')) 

Please help me find a solution for this.