Feature request criteria

Dencel · **Joined:** Tue Jan 27, 2004 12:22 pm **Posts:** 103

Hibernate version:3.0

It would be functional to have a function like criteria.getCriteria("foo"),
which:
1. returns a existing criteria object associated with the foo
2. creates the criteria if it doesn't exist.

Usage scenario:

class myAction

Criteria foo = ..FooBarClass.class..
// Set some default selection criteria

// add user selection criteria
// Error: FooBarClass.associatedClass already exists in criteria

marco-p · **Posted:** Tue Jul 19, 2005 5:46 am

That's what the named query are there for.
Why a criteria would be more useful for you ? And a kinda complex cache must be used to handle Criteria, IMO is much more the pain than the gain. Can you provide a better use case for what you think ?

Dencel · **Joined:** Tue Jan 27, 2004 12:22 pm **Posts:** 103

Hi marco,

That's what I'm doing now.. keeping a simple Hashtable cache for the different criteria objects (that's not complex).

The use case is following:
I want to seperate the Ordering and Selection criteria in my source code. Thus I require to re-use the different Criteria objects (I have simple logic to retrieve the criteria object based on property provided).
I don't know the implementation of Criteria, but isn't there a reference to the previous Criteria objects? This would make the get method simple to implement.

If naming aliases is the only solution I will implement it that way, but I would prefer this way.

marco-p · **Posted:** Tue Jul 19, 2005 6:29 am

For what I know, every method in Criteria modifies the objects and return a reference to the object itself (return this).
To implement what you're saying, you should clone the Criteria object and then apply the order, but I don't know if it's possible.
In a similar situation, I didn't bother to cache the Criteria object (is it really a big deal ?) and simply re-applied the method (in my case was the projection, but it's the same with order ).

Dencel · **Joined:** Tue Jan 27, 2004 12:22 pm **Posts:** 103

I don't really understand what you mean with reapply. Can you give an example? Currently I am doing something like this:

Code:

Criteria c = session.createCriteria(FooClass.class)
.add(Restri...);
localCriteriaCache.put("root",c);
c=c.createCriteria("bar").add(Restr...);
localCriteriaCache.put("bar",c);

and later in the code...

Code:

localCriteriaCache.get("bar").addOrder(Order.desc("foobar");

Note: this code gives an error

Code:

Criteria c = session.createCriteria(FooClass.class)
.add(Restri...)
.createCriteria("bar").add(Restr...);
....
c.createCriteria("bar").addOrder(Order.desc("foobar"));

marco-p · **Posted:** Tue Jul 19, 2005 9:31 am

Dencel wrote:

Note: this code gives an error

Code:

Criteria c = session.createCriteria(FooClass.class)
.add(Restri...)
.createCriteria("bar").add(Restr...);
....
c.createCriteria("bar").addOrder(Order.desc("foobar"));

I may be wrong, but the error is cause by the createCriteria("bar"), 'cause it declares a self join without specifying an alias. Try to just add the order:

Code:

Criteria c = session.createCriteria(FooClass.class)
.add(Restri...)
.createCriteria("bar").add(Restr...);
....
c.addOrder(Order.desc("foobar"));

The problem is that the method addOrder just adds the order, so if you apply a different order later on the same criteria, the orders will be applied together... uhm, so the only solution seems to be to clone the criteria object... [/b]

Dencel · **Joined:** Tue Jan 27, 2004 12:22 pm **Posts:** 103

Marco,

Your solution doesn't solve my problem. Anyway I'll check the sourcecode and see how it's implemented. Rewarding you the credits for the help. Thank you.