Hibernate many-to-many: Criteria for looking up all class A which contains class B

Question

I have 2 classes which have many to many relationship. I take the \'Question\' and \'Tag\' as an example to make the case more understandable.

For each question,

Answer 1

Essentially, you need to create an alias and use the alias to query the child collection like so:

List questions = sess.createCriteria(Question.class)
    .createAlias("Tags", "t")
    .add( Restrictions.eq("t.name", "hibernate") )
    .list();

I'm assuming you don't actually have a class that represents the "bridge" table to the tags table in this scenario, otherwise you'd need to create 2 aliases eg:

List questions = sess.createCriteria(Question.class)
        .createAlias("QuestionTag", "qt")            
        .createAlias("qt.Tags", "t")
        .add( Restrictions.eq("t.name", "hibernate") )
        .list();

You can find out more from the docs:

http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html/querycriteria.html#querycriteria-associations