Re: Id column = null?

Thu, 06 Sep 2007 07:29:53 -0700 

Hi Łukasz,
Can you please file a JIRA on this? The @Id annotation on the getId was illegal since it didn't have a corresponding setId method. This should have been flagged as an error. 

Thanks,

Craig

On Sep 6, 2007, at 6:56 AM, Xh wrote:


Hi Christian!

Yes, You are absolutely right, I didn't have setter for that field.

thanks!
best regards
Łukasz

----- Original Message ----
From: Christian Defoy <[EMAIL PROTECTED]>
To: [email protected]
Sent: Thursday, 6 September, 2007 3:46:58 PM
Subject: Re: Id column = null?

Hi,

It is probably because you do not have a setId() method in your
WebPage class.  Since you are using Property access, you must define
setters for every field (or at least that's how I understand it).  If
you were using Field access, you wouldn't have that issue.

Hope this helps!

Christian

On 9/6/07, ben short <[EMAIL PROTECTED]> wrote:

Are you doing all your work within a transacion? I wonder if the ids
are not being set as ou havent tried to access them within a
transaction.

On 9/6/07, ben short <[EMAIL PROTECTED]> wrote:

Maybe you could try and load one of the WebPage objects directly
rather than via the WebModule and see if the id gets set?

On 9/6/07, Xh <[EMAIL PROTECTED]> wrote:

Hi Ben!

Both WebModule and WebPage have id column name 'id'.

best regards
Łukasz


----- Original Message ----
From: ben short <[EMAIL PROTECTED]>
To: [email protected]
Sent: Thursday, 6 September, 2007 3:13:59 PM
Subject: Re: Id column = null?

Whats the id column name on the WebPage table?

On 9/6/07, Xh <[EMAIL PROTECTED]> wrote:

Hi Ben!

Data already exists in database (so it is commited ;) ).
All I try to do is to fetch those data.


Besides, it is very weird that ID for WebModule works and for  
WebPage does not.


Changing GenerationType to AUTO does not solve the problem.

best regards
Łukasz

----- Original Message ----
From: ben short <[EMAIL PROTECTED]>
To: [email protected]
Sent: Thursday, 6 September, 2007 1:20:59 PM
Subject: Re: Id column = null?

Try changing to GenerationType to AUTO eg

 @GeneratedValue(strategy = GenerationType.AUTO)


I think that the GenerationType.IDENTITY dosent assign the ids  
to the
rows until its commited to the db, so any relations are written  
to the

db as nulls.

Ben

On 9/6/07, Xh <[EMAIL PROTECTED]> wrote:

Hi All!

I have build two entities atop existing database.
 I have successfully created OneToMany   bidirectional mapping.
The mapping is WebModules (one) - WebPage (many)


I can fetch WebModules, display their IDs and iterate through  
associated WebPages.

 BUT WebPages IDs are set to null.

 For example, the below code:


// wef is my SessionBean, it calls WebModule's NamedQuery and  
returns found module

WebModule module = wef.findWebModuleByName("Add");

// module id is displayed properly, e.g. 2

response.getWriter().write(

        module.getId() + ":" + module.getDescription() + "<br/ 
>");


// iterate through associated WebPages

for (WebPage page : module.getPages()) {

// id is displayed as null
// title is displayed properly

    response.getWriter().write("<br/>" + page.getId());
    response.getWriter().write("<br/>" + page.getTitle());
}


Of course the pages' ids are not null, they are primary keys  
with automatically generated identities.


I don't get it, maybe it's something wrong with my classes?
 Here they are:

@Entity
 @Table(name="dw_modules",schema="dw")
 @NamedQuery (
     name = "findWebModuleByName",
     query = "SELECT wm FROM WebModule wm WHERE wm.name = :name"
 )
 public class WebModule implements Serializable {
     private Integer id;
     private Set<WebPage> pages = new HashSet<WebPage>();
 ...
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     public Integer getId() {
         return id;
     }
 ...
 }

 @Table(name = "dw_pages", schema = "dw")
 public class WebPage implements Serializable {
     private Integer id;
     private WebModule parentModule;
 ...
...
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     public Integer getId() {
         return id;
     }
 ...
 }

thanks for any hints
 best regards
 Łukasz




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Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!




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