loading all the objects from a particular class

tireetoo · **Joined:** Thu Jan 15, 2004 11:16 am **Posts:** 37

How do I load all the objects of a particular type.
I have a single system object of which there should only be one. I dont know its ID.

If there is more than one then I want to throw an error.

Ta,
Stuart.

Myk · **Joined:** Sun Jan 04, 2004 2:46 pm **Posts:** 147

Code:

List list = sess.find( "from SystemType" );
if ( list.size() != 1 ) throw new Exception( "..." );

Cheers.

Myk.

emmanuel · **Posted:** Thu Feb 12, 2004 1:55 pm

session.iterate will be better actually.

msheftel · **Joined:** Thu Oct 09, 2003 3:42 pm **Posts:** 22

emmanuel wrote:

session.iterate will be better actually.

Wouldn't session.iterate execute a sql statement for each object while session.find would execute one statement to load all of the objects.

E.g. if there were 10 SystemType objects in the database.
Session.find would execute one query to load all of the objects
Session.iterate would execute 11 queries (one to get a list of identifiers and then one for each object)

emmanuel · **Posted:** Thu Feb 12, 2004 5:12 pm

That's the whole point.
Read the initial post

Quote:

If there is more than one then I want to throw an error.

It will only do 1 request.

michael · **Posted:** Thu Feb 12, 2004 5:21 pm

Just do session.iterate().hasNext() ... wil do only one request for the id.

tireetoo · **Joined:** Thu Jan 15, 2004 11:16 am **Posts:** 37

You guys are just great. I now have a nice working method. And If I am able to call hasNext() twice then I throw an exception.

Thanks for all the help.

tireetoo · **Joined:** Thu Jan 15, 2004 11:16 am **Posts:** 37

Well actually when I try this with HSQLDB I get the following error...

[junit] ------------- Standard Output ---------------
[junit] Hibernate: select from
[junit] ------------- ---------------- ---------------

[junit] Caused by: java.sql.SQLException: Unexpected token: FROM in statement [select
om]
[junit] at org.hsqldb.jdbcResultSet.<init>(Unknown Source)
[junit] at org.hsqldb.jdbcConnection.executeStandalone(Unknown Source)
[junit] at org.hsqldb.jdbcConnection.execute(Unknown Source)
[junit] at org.hsqldb.jdbcStatement.fetchResult(Unknown Source)
[junit] at org.hsqldb.jdbcStatement.executeQuery(Unknown Source)
[junit] at org.hsqldb.jdbcPreparedStatement.executeQuery(Unknown Source)
[junit] at net.sf.hibernate.impl.BatcherImpl.getResultSet(BatcherImpl.java:83)
[junit] at net.sf.hibernate.loader.Loader.getResultSet(Loader.java:794)
[junit] at net.sf.hibernate.hql.QueryTranslator.iterate(QueryTranslator.java:846)
[junit] at net.sf.hibernate.impl.SessionImpl.iterate(SessionImpl.java:1540)

Looks like the SQL statement is not complete.
Ta,
Stuart.

michael · **Posted:** Fri Feb 13, 2004 9:13 am

What are your mappings and the query you execute?

tireetoo · **Joined:** Thu Jan 15, 2004 11:16 am **Posts:** 37

apologies for lack of information and late reply. Tonsillitis:-(

I am using xdoclet to generate my mappings but was failing to add all my mappings to the hibernate.cfg.xml file.

I now get the result...
Hibernate: select tireesyste0_.id as x0_0_ from TireeSystem tireesyste0_

Which is great!
Thanks for all the help.
Stuart.