Comments in-line.
On 2/13/08 1:48 PM, "Eric Polino" <aluin..mail.com> wrote:
> I've started using Cayenne a few weeks ago for our project,
> www.campgroundautomation.com. In the process of working with it, I've
> come across a few things I don't understand. After reading the API
> and the UserGuide, can't find much to help me.
>
> 1. How do I count the rows of a query, without actually doing a full
> blown SelectQuery and counting the elements? ie: select count(*) from
> table;
Various aggregate queries come up rather frequently on the list. I think
someone posted a utility class at one time you could use. Otherwise,
SQLTemplate will get you there.
http://cayenne.apache.org/doc/sqltemplate-basics.html
> 2. I've read in many places how Cayenne deals with joins for you, but
> nowhere do I see an example of how its done. Here's an example
> problem I'm dealing with.
>
> Schema:
>
> Reservation (n to 1) Site
> Site (n to 1)
> Site contains a type field
>
> I want to get all the Reservations of a given for a given type of
> site. In sql I would execute something like, "select * from
> Reservation, Site, SiteType where SiteType.Name='Something' and
> Site.typeID = SiteType.id and Reservation.siteID = Site.id"
>
> Short of writing an parameterized sql string and executing that in my
> code, how do I do that with Cayenne? I hope I explained all that well
> enough...make sense?
Just map the relationships in the modeler. Cayenne takes care of the SQL
for you. The following guide should help you get started with the modeler:
http://cayenne.apache.org/doc20/tutorial-starting-mapping-project.html
-- Kevin
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