如何创建标准，其中参数是表上集合字段的成员？

Question

I have a class that has the following structure:

public class Machine {
    private Set<Line> lines;
}

Now what I want to to is create a query with Criteria where I can get all the machines that contain a specific line.

I noticed Criteria has a Restrictions.in() but that checks whether a field of the table is in a Collection and I want to do it the other way around.

Thanks for helping me out, Cheers, Stef

Answer 1

Following Hibernate documentation should help: http://docs.jboss.org/hibernate/orm/4.0/manual/en-US/html/querycriteria.html#querycriteria-associations

Basically you'll need to create a 2nd criteria that refers to the elements of lines of the Machine class. ie

Criteria machineCriteria = session.createCriteria(Machine.class);
Criteria lineCriteria = machineCriteria.createCriteria("lines");
lineCriteria.add(Restrictions.eq("fieldNameOfLineClass", valueOfFieldNameOfLineClass);
machineCriteria.list();

Answer 2

I find this syntax more meaningful as well as more compact. Presuming that you have the id of a Line instance in your hand this would get you what you want.

    // we have a Long lineId
    Criteria crit = session.createCriteria(Machine.class)
        .createAlias("lines", "line")
        .add(Restrictions.eq("line.id", lineId);