Question

let’s say i have this classes which are being mapped to SQLServer:

class Statistic {
    Servicos servico
    int totalTime
    Date date

    static constraints = {
    }
}

class Servicos {

    String name
    String description

    static constraints = {
    }
}

Using SQL Queries like this:

select name, description, media,frequencia from TvMagazinePlus.dbo.servicos as t1 join (

    SELECT TOP 1000 
          [servico_id]
          ,avg([total_time]) as 'media'
          ,COUNT([servico_id]) as 'frequencia'
      FROM [TvMagazinePlus].[dbo].[statistic] where date between now and yesterday  group by [servico_id]) as t2 on t1.id = t2.servico_id

I get this table:

I now need to render the result in JSON. My problem is, i find executeQuery too difficult to accomplish this. Is there any way i can do this using HQL like createCriteria?

Answer 1

You could easily set that result in a list of beans and then serialize them in JSON with any framework like Jackson or anything…

I don’t know grails but with Hibernate you can use criteria to execute subqueries, according to the hibernate documentation:

http://docs.jboss.org/hibernate/core/3.3/reference/en/html/querycriteria.html

DetachedCriteria avgWeight = DetachedCriteria.forClass(Cat.class)
    .setProjection( Property.forName("weight").avg() );
session.createCriteria(Cat.class)
    .add( Property.forName("weight").gt(avgWeight) )
    .list();

This obviously return the cats that have a weight greater than the average cat’ weight, using a subquery to get that average cat’s weight.

To map the result into an XML/JSON serializable bean you can simply use a AliasToBeanResultTransformer on that criteria and then serialize your objects 😉