Re: Trying to build simple recommender, but getting SQLException

[Grant Ingersoll]

I'm pretty sure that user id's now need to be longs.

On Oct 12, 2009, at 4:28 PM, Larry Homes wrote:
Hello,

I am trying to just build a simple Recommender system using a
SlopeOneRecommender. I used the sample table schema and data found  
in the
javadoc here:
http://lucene.apache.org/mahout/javadoc/core/org/apache/mahout/cf/taste/impl/model/jdbc/MySQLJDBCDataModel.html 
.
Here is a select * from the table:

mysql> select * from taste_preferences;
+---------+---------+------------+
| user_id | item_id | preference |
+---------+---------+------------+
| abc     | 123     |        0.9 |
| abc     | 456     |        0.1 |
| def     | 123     |        0.2 |
| def     | 789     |        0.3 |
+---------+---------+------------+
4 rows in set (0.00 sec)


When I try to run the recommender I get this error:

java.util.NoSuchElementException: Can't retrieve more due to
exception: java.sql.SQLException: Invalid value for getLong() - 'abc'
	org.apache.mahout.cf.taste.impl.model.jdbc.AbstractJDBCDataModel 
$ResultSetIDIterator.nextLong(AbstractJDBCDataModel.java:684)
	 
org.apache.mahout.cf.taste.impl.recommender.slopeone.MemoryDiffStorage.buildAverageDiffs 
(MemoryDiffStorage.java:220)
	 
org.apache.mahout.cf.taste.impl.recommender.slopeone.MemoryDiffStorage 
.<init>(MemoryDiffStorage.java:115)
	 
org.apache.mahout.cf.taste.impl.recommender.slopeone.SlopeOneRecommender 
.<init>(SlopeOneRecommender.java:63)
        Recommend.doGet(Recommend.java:67)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:802)



Here is the code:

//Bunch of imports here

public class Recommend extends HttpServlet
{
   private static final long serialVersionUID = 1L;
   DataSource ds = null;

   public void init()
   {
       String DATASOURCE =
getServletContext().getInitParameter("DataSource");

       try
       {
           super.init();

           if ((ds = (DataSource) (new
InitialContext().lookup(DATASOURCE))) == null)
               throw new ServletException("Error configuring  
DataSource.");
       }
       catch (NamingException e)
       {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
       catch (ServletException e)
       {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
   }

   protected void doGet(HttpServletRequest request,  
HttpServletResponse
response) throws ServletException, IOException
   {
       PrintWriter pw = response.getWriter();
       DataModel model = new MySQLJDBCDataModel(ds,  
"taste_preferences",
"user_id", "item_id", "preference");
       // Make a weighted slope one recommender
       Recommender recommender;
       Recommender cachingRecommender;
       try
       {
           recommender = new SlopeOneRecommender(model);
           cachingRecommender = new CachingRecommender(recommender);
           List<RecommendedItem> l = cachingRecommender.recommend 
(123, 2);
           Iterator<RecommendedItem> i = l.iterator();

           while(i.hasNext())
           {
               pw.println(i.next().getItemID());
           }

       } catch (TasteException e)
       {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }
   }

   protected void doPost(HttpServletRequest request,  
HttpServletResponse
response) throws ServletException, IOException
   {

   }

}


If you need any other data, feel free to ask.

Thanks

--------------------------
Grant Ingersoll
http://www.lucidimagination.com/

Search the Lucene ecosystem (Lucene/Solr/Nutch/Mahout/Tika/Droids)  
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