Question

I have a Tag class like this:

public class Tag {

    private Long id;

    private String title;
    private Set<Document> documents = new HashSet<Document>();

    public Tag(){}

//getter and setter...

}

And a class Document clasified by some tags object

public class Document {

    private Long id;

    private String title;
    private Int numberPages;
    private Set<Tag> tags = new HashSet<Tag>();

    public Document(){}

//getter and setter...

}

And now I would like get documents with a 10 pages maximun and they have tags “short” OR “essay”

I guess something like:

int nPages = 10;
Query query = session.createQuery("from Document where nPages <= :numberPages and (<<short>> OR <<essay>>);  
query.setInteger("numberPages", nPages);  

The list of tags could be variable. And I would like differentiate when have to be all tags (“AND” between tags) or with any tag is enough (“OR” between tags)

How can I build the sql statement?

Answer 1

I think your HQL should look like below:

  Query query = session.createQuery(
           "from Document d join d.tags t "+
           " where d.nPages <= :numberPages and "+
              " t.title in (:titles) "; 
  List<String> titles = new ArrayList<String>();
  titles.add("short");
  titles.add("essay");
  query.setParameter("numberPages", nPages);  
  query.setParameterList("titles", titles);