Newbie: How to use Criteria to Query this?

chrischi · **Joined:** Sun Aug 05, 2007 8:01 pm **Posts:** 4

1. How can I use "Criteria.class" to do such things?

Code:

String hql = "FROM Cat cat WHERE cat IN (?) AND ...";

2. There are a many-to-many relation between Cats.
Cat.java

Code:

private Set<Cat> friends = new HashSet<Cat>(0);

How to use "Criteria.class" to find cats which having relation of a List<Cat>.

Thank You.

sethrohit1977 · **Joined:** Mon Jan 22, 2007 10:32 am **Posts:** 101

For this kind of query you need to access cat table twice and as far as I know that not possible through criteria queries, i.e you can join twice to a table through criteria query.

chrischi · **Joined:** Sun Aug 05, 2007 8:01 pm **Posts:** 4

sethrohit1977 wrote:

For this kind of query you need to access cat table twice and as far as I know that not possible through criteria queries, i.e you can join twice to a table through criteria query.

How about

Cat.java

Code:

private Set<Dog> friends = new HashSet<Dog>(0);

Between Cat and Dog table, there have a relation table. Thank You.

sethrohit1977 · **Joined:** Mon Jan 22, 2007 10:32 am **Posts:** 101

List data = sess.createCriteria(Cat.class).createCriteria("friends").add(Restrictions.isNotNull("id")).list();

assuming "id" is a valid property in Dog.

chrischi · **Joined:** Sun Aug 05, 2007 8:01 pm **Posts:** 4

sethrohit1977 wrote:

List data = sess.createCriteria(Cat.class).createCriteria("friends").add(Restrictions.isNotNull("id")).list();

assuming "id" is a valid property in Dog.

If I have a List<Dog> dogs, is there any way to query:

sess.createCriteria(Cat.class).createCriteria("friends").add(Restrictions.in(........., dogs)).list();?

Thank You

sethrohit1977 · **Joined:** Mon Jan 22, 2007 10:32 am **Posts:** 101

May be I am not able to get your question. If you can explain what you need to do along with relationship between entities, I might be able to help.

chrischi · **Joined:** Sun Aug 05, 2007 8:01 pm **Posts:** 4

sethrohit1977 wrote:

May be I am not able to get your question. If you can explain what you need to do along with relationship between entities, I might be able to help.

I already have a list of dogs, and I would like to find related cats.

DB:
[cat] --+-- [cat_and_dog_relation] --+-- [dog]

in Cat.java

Code:

int catid;
[attributes....]
private Set<Dog>    dogs    = new HashSet<Dog>(0);

in Dog.java

Code:

int dogid;
[attributes....]
private Set<Cat>    cats    = new HashSet<Cat>(0);

At first, I query:

Code:

List<Dog> dogs = getDogsGroup(1);
Criteria crit = session.createCriteria(Cat.class);
Criteria dogCrit = crit.createCriteria("dogs");
??????

And how to continue? Thank You Very Much.