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 Post subject: Hibernate native SQL returns a String instead of an Object[]
PostPosted: Sun Aug 20, 2017 6:45 pm 
Newbie

Joined: Sun Nov 29, 2015 4:27 pm
Posts: 8
I have the code:
Code:
@Override
   public SQLQueriesResult execute(SQLQueries action, ExecutionContext context) throws ActionException {

      Session session = null;
      index_grid = 0;
      Integer count = 0;

      Integer offset = action.getLoadConfig().getOffset();
      Integer limit = offset + action.getLoadConfig().getLimit();
      List<SQLRecord> records = new ArrayList<SQLRecord>();

      try {
         session = sessionFactory.openSession();
         String sql = null;
         if (action.isLiveGrid()) {
            sql = liveGridSQL(action.getSql(), limit, offset);
         } else {
            sql = action.getSql();
         }
         SQLQuery query = session.createSQLQuery(sql);

         List<MetaDataFieldConfigSQL> columns = SQLToolsImpl.getColumnFromSQL(session, sql);
         for (int i = 0; i < columns.size(); i++) {
            query.addScalar(columns.get(i).getFieldName());
         }
         Iterator<Object[]> result = query.list().iterator();
            while (result.hasNext()) {
            [b]Object[] type = (Object[]) result.next(); -- this error[/b]            
                                System.out.println(type);
         }
         
         /*
         for (int i = 0; i < result.size(); i++) {
            SQLRecord sqlRecord = new SQLRecord();
            sqlRecord.addField("INDEX_GRID", ++index_grid);
            for (int j = 0; j < columns.size(); j++) {
               sqlRecord.addField(columns.get(j).getFieldName().toUpperCase(),
                     getFieldValue(columns.get(j).getFieldType(), result.get(j)));
               System.out.println(result.size());
            }
            records.add(sqlRecord);
         }
         */
         if (!action.isLiveGrid()) {
            count = records.size();
         }
      } catch (JSQLParserException e) {
         e.printStackTrace();
      } finally {
         session.close();
      }
      return new SQLQueriesResult(
            new PagingLoadResultBean<SQLRecord>(records, records.size(), action.getLoadConfig().getOffset()),
            count);
   }


Why does hibernate return 'String' instead of Object []?

Error:
Code:
[ERROR] Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to [Ljava.lang.Object;
[ERROR]    at pl.cba.lukaszbaczek.webmuseum.gui.gxt.widgets.sqlGrid.server.data.SQLQueriesHandler.execute(SQLQueriesHandler.java:74)
[ERROR]    at pl.cba.lukaszbaczek.webmuseum.gui.gxt.widgets.sqlGrid.server.data.SQLQueriesHandler.execute(SQLQueriesHandler.java:26)
[ERROR]    at com.gwtplatform.dispatch.rpc.server.AbstractDispatchImpl.doExecute(AbstractDispatchImpl.java:154)
[ERROR]    ... 43 more
[ERROR]


Hibernate Version is 5.1.0.Final


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 Post subject: Re: Native SQL not return Object[]
PostPosted: Wed Aug 23, 2017 3:32 am 
Hibernate Team
Hibernate Team

Joined: Thu Sep 11, 2014 2:50 am
Posts: 1630
Location: Romania
If you call addScalar(alias) only once, you get a List<T> where T is the inferred type of the single column being selected.

If you call addScalar(alias) multiple times, you get a List<Object[]> instead.

You got the ClassCastException because you are in the first situation.

There are many other issues with your approach:

- It looks like you are using a custom-made pagination query building instead of the Hibernate-based one
- It looks like you want a Tuple result which is simpler than your approach or a ResultTransformer
- Don't use e.printStackTrace() because you are going to write to the System.out stream. Use a Logging framework to pass the exception.
- You don't use explicit transactions, and that's almost always a bad idea.


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