Solr vs Hibernate Search

May 7, 2011


We are looking to implement indexing in our site and evaluated SolrJ (The java client library to access Lucene) and Hibernate Search (that also uses Lucene). Hibernate was very a tempting option given we already use Hibernate as the ORM. It just seems so elegant and simple. Also Hibenate takes care of updation to the […]

Posted in: Hibernate, Solr

Projection and aggregate functions in Hibernate

April 18, 2011


I needed to aggregate columns (Sum, Count etc.) and display results in a JSP (thru Struts) … with the same convenience as regular attributes for a persistent class. String queryString = “select product.productName as productName, count(billQuantity) as countBillQuantity, sum(billAmount) as totalBillAmount from bill group by product.productName”; Query queryObject = getSession().createQuery(queryString); queryObject.setResultTransformer(Transformers.aliasToBean(QueryResultSummary.class)); QueryResultSummary is a class […]

Posted in: Hibernate

XStream … ArrayIndexOutOfBoundsException

March 29, 2011


Spent a frustrating unproductive day trying to narrow down an XStream XML writer error that just says ” java.lang.ArrayIndexOutOfBoundsException: -1″ with no clues. It’s just a dumb mistake of missing writer.endNode  not matching writer.startNode Wouldn’t this be common error that deserved better messaging ??

Posted in: XStream

Hibernate TransactionException: Transaction not successfully started

November 13, 2010


If you got this cryptic error … among other issues … this could because you had one transaction embedded inside another. MethodA(){ …. objectDAO.getSession().beginTransaction();; MethodB(); objectDAO.getSession().getTransaction().commit() …. } MethodB(){ …. anotherObjectDAO.getSession().beginTransaction();//<===Begining a transaction inside another transaction … REMOVE THIS; anotherObjectDAO.getSession().getTransaction().commit()//<===Begining a transaction inside another transaction … REMOVE THIS …. } You may have […]

Posted in: Hibernate

Struts Datetimepicker control not working

October 21, 2010


Struts Datetimepicker doesn’t work. PERIOD. It is bulky, slow, buggy and doesn’t work in Firefox. Just switch to jQueryUI Datepicker … it works like a breeze. Step 1 – Download and add the links to the jQuery templates and scripts <link type=”text/css” href=”./css/ui-lightness/jquery-ui-1.8.5.custom.css” rel=”stylesheet” /> <script type=”text/javascript” src=”./js/jquery-1.4.2.min.js”></script> <script type=”text/javascript” src=”./js/jquery-ui-1.8.5.custom.min.js”></script> Step 2 – Add […]

Posted in: jQuery, Struts2

Unknown Faceted Project Problem (Java Version Mismatch)

September 25, 2010


If you upgraded or downgraded the Java Compiler version in Eclipse … you may see Unknown Faceted Project Problem (Java Version Mismatch) You need to take a look at Project Properties > Project Facets … and this must match the Java compiler compliance level. Refer to this link for more details ….

Posted in: Eclipse IDE

Hibernate mySQL connection lost overnight

September 19, 2010


Using tomcat + mySQL + Hibernate … Your application works fine … then you wake up in the morning and try to use it … it crashes. You restart Tomcat … it works fine again. There are a lot of posts on the internet about this 8 hour problem To fix it … 1. Change […]

Posted in: Hibernate