I am using the fancy new projection to get a count of rows, and then I want to re-run the same criteria as a list. This is just a simple pager.

It generally goes like this :


This leaves the critiera in a permanant 'projection' state, which I need to get out of.
The base Critieria interface has no methods for getProjection/getResultTransformer, only to set them, but the CritieraImpl itself does.

So this is what I do to get around this, which is basically just cast, save old values, and then re-set:


Is this an oversight that will be changed, or is there a reason for this? There is no way for me to poke at projectionCritieria ( which is just set to 'this') so I'm not sure I'm not leaving something in a bad state.

Thanks,
Andrew Backer

I can't think of a good reason to get a Criteria's current projection. I'm pretty sure that you don't need to use a projection for what you're doing: just use the criteria in the normal way, and use the size() method on the returned list. That way you only have to go to the DB once, to get the actual result set.

Note that you can use setProjection(null) if you want to undo the rowCount thing.

Not sure if that is a good idea. This is a list (potentially) of hundreds of thousands of records, so I don't see how it could be a good idea to return every record in the table just to count the size of this query. Were I coding this by hand I would not (nor would anyone else) think of pulling down a record set of huge size to call rs.last(); rs.getRowNumber().

I thought this was the case this was introduced for. I am new, but I recall talk of people writing custom hql solutions just to get the rowcounts, and that some other custom solutions should be bypassed because HB3 was going to move towards this idea of projections.

Myself, I can't think of a good reason to get the projection either. Well, there is no good reason if you are able to reset it. Since you *can't* reset the properties that setProjection() modified (the point of the post) you need to do it this way so you can preserve/reset them after.

I use the same critiera for count & listing. If I do not do this I make two copies (identically constructed) of a critiera and then call count on one and list on the other.

To be more explicit, here is the use case :
1. Construct complex criteria
2. call countResults()
3. set max results, first record # (for offset/limit)
4. call list()
... viola, a simple recordset pager that only retrieves one page of data at a time.

So, what I am doing actually does _work_, but I am not sure this is the way it was intended to be. Is the fact that you can't un-set a projection an oversight, or is there some super easy way to clone criteria so that I don't have to do the creation process twice.

- Andrew

You can reset/unset the project: criteria.setProjection(null) works just fine. Note that you have to set the result transformer afterwards, because just calling setProjection, even setProjection(null), changes the result transformer to PROJECTION. You probably want to set it to ROOT_ENTITY or DISTINCT_ROOT_ENTITY.