Id column = null?

[Xh <xh...@yahoo.co.uk>]

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




      ___________________________________________________________ 
Want ideas for reducing your carbon footprint? Visit Yahoo! For Good  http://uk.promotions.yahoo.com/forgood/environment.html

Re: Id column = null?

[ben short <ja...@gmail.com>]

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 <xh...@yahoo.co.uk> 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
>
>
>
>
>       ___________________________________________________________
> Want ideas for reducing your carbon footprint? Visit Yahoo! For Good  http://uk.promotions.yahoo.com/forgood/environment.html
>