[postgis-users] Can save but not retrieve using Hibernate+PostGIS+JTS

[Maria Arias de Reyna]

El Thursday 26 August 2010, Paulo Angelo escribió:
> Hi Ppl,
>
>   I'm getting a weird problem. I can save a Geometry type through Hibernate
> but I can't retrieve it.
>
>  WKTReader fromText = new WKTReader();
>  Geometry geom = fromText.read("POLYGON((0 0,0 3,3 3,3 0,0 0))");
> Session session = dao.newSession();
> Transaction tx =  dao.beginTransaction(session);
> Query q = session.createQuery("select f from Geometries f");
> List list = q.list();
> Poligono to = (Poligono) lista.get(0);
> dao.commitTransaction(session, tx);
> to.setPoli(geom);
> System.out.println(to.getPoli().toString());  // Apears "POLYGON ((0 0, 0
> 3, 3 3, 3 0, 0 0))"
> dao.alterar(to, null, null);
>  // I can see via SQL that it saves correctly

And have you checked that it appears in the database after the commit? Maybe 
the commit is not really commited (can't see why, though).

> // Now, retrieve
> session = dao.newSession();
> tx =  dao.beginTransaction(session);
> q = session.createQuery("select f from Geometries f");
> list = q.list();
> to = (Poligono) lista.get(0);
> dao.commitTransaction(session, tx);
> System.out.println(to.getPoli().toString());
>  // Get a *NullPointerException*, because to.getPoli() is null
>

Have you tried debugging step by step checking that all variables are ok? Are 
you sure that "to" is not null instead of to.getPoli()?

Have you tried using Criteria instead of hql? Maybe it is a conversion problem 
between geometry types. 

Could it be that closing/commiting the transaction is the problem? If 
hibernate didn't get all the data on one shot, closing the transaction makes 
hibernate unable to get more info from the database.

Anyway, if you rollback a read-only transaction instead committing, hibernate 
goes faster.


-- 
María Arias de Reyna Domínguez
Área de Operaciones

Emergya Consultoría 
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