[rules-users] Guvnor, database and rule language

[Anu@work]

Thx. I now understand the part about the rule being fired for all customers
in memory. However, how do I achieve this on customer signup?

Given a TN in real time, I need to look up in the database if it is already
existing and if balance is greater than 0. If so, then do not allow signup. 

btw, "hibernateSession.createQuery" expression validated in guvnor without
any problems. I had to declare hibernateSession as a global and set it in
the execution server. It actually fires also and I do nto see any errors but
I can't see the results anywhere. 


Greg Barton wrote:
> 
> 
> First off, the query should be:
> 
> from Customers where TN = :tn and balance > 0
> 
> And that would be only if you mapped the tn property to the name "TN". HQL
> queries are case sensitive when it comes to property names:
> http://www.hibernate.org/hib_docs/v3/reference/en-US/html_single/#queryhql-casesensitivity
> 
> Second, I don't know if that whole "hibernateSession.createQuery"
> expression would compile in a DRL file.  Have you tried it?  Anyone?
> 
> Finally, this rule will fire for every Customer in working memory and look
> up a matching Customer in the database.  Seems a bit inneficient,
> especially if you have many rules of this type. Would it be possible to
> load the Customer from the database and just insert it into working memory 
> with it's "balance" property already set?  That would be far simpler. 
> Then the rule would be:
> 
> global org.hibernate.Session hibernateSession;
> 
> when 
>     cust1:Customer(balance > 0)
> then
>     cust1.setIsAllowed(false);
>     hibernateSession.save(cust1);
> end
> 
> (Ignoring the transaction management, here.)
> 
> You could even skip the save() on the hibernate session in the rule
> action.  You could keep the hibernate session open and save the Customers
> when you've completed all changes.
> 

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