[rules-users] some pointers for solution

[Greg Barton]

In this case the accumulate clause is maintaining a counter (total) that's incremented whenever a Criteria is detected that is contained in both the Data and Query object matched in the rule.  So:

# Find Criteria that are contained in both the Data and Query
from accumulate( Criteria( this memberOf d, this memberOf q ),
# Initialize the counter to 0
  init( int total = 0; ), 
# Increment when the above condition is  matched
  action( total ++; ),
# Decrement if a matched Criteria now fails to match
  reverse( total --; ),
# return the total when all known Criteria are matched
  result( total ) )

--- On Sun, 11/8/09, Wishing Carebear <wishing.carebear at gmail.com> wrote:

> From: Wishing Carebear <wishing.carebear at gmail.com>
> Subject: Re: [rules-users] some pointers for solution
> To: "Rules Users List" <rules-users at lists.jboss.org>
> Date: Sunday, November 8, 2009, 11:39 AM
> Hi Greg:
> I'm trying to understand your first
> solution.
>  
> Ran the project and it works fine. If possible could
> you explain me little bit on : 
> 
> from accumulate( Criteria( this memberOf d,
> this memberOf q ),
> init( int total = 0; ),
> action( total ++; ),
> reverse( total --; ),
> result( total ) )
>  
>  
> Thanks,
> cabear
> 
> 
> 2009/11/8 Greg Barton <greg_barton at yahoo.com>
> 
> There are a couple of
> ways to do this.  I'm sure there's a bit more clean
> way than the example I'm providing, but this should get
> you in the right direction.  It's not 100% rules,
> because it involves a bit of java collections trickery. (See
> attached project, collection_DroolsCriteriaMatch.tar.gz)
> 
> 
> The heart of it is a single rule:
> 
> rule "Match"
>  when
>    d : Data()
>    q : Query( size <= d.size )
>    Number( intValue == q.size )
>    from accumulate(
>      Criteria( this memberOf d, this memberOf q ),
> 
>      init( int total = 0; ),
>      action( total ++; ),
>      reverse( total --; ),
>      result( total )
>    )
>  then
>    System.out.println("Match: " + d + "
> and " + q) ;
> end
> 
> The Data object holds data to be queried, Query objects are
> asserted to match the Data, and Criteria objects can be
> contained in either. (With the aforementioned collections
> trickery that if a Criteria is contained in a Query it can
> be found in a Data object, but the reverse isn't true.
>  See the Query.contains(Object) method for how that's
> implemented.)
> 
> 
> So the rule above basically says "There's a Data
> object, and all of the Query objects Criteria are contained
> in the Data object."
> 
> There's an alternate way of doing this using eval and a
> bit more java fu.  See the eval_DroolsCriteriaMatch.tar.gz
> project attached.  This one's probably not optimal,
> though, as it's basically a brute force check of all
> Data objects against the asserted Query.
> 
> 
> I tried for a while to get a solution working with
> different criteria types from both Data and Query objects
> being asserted into working memory, but I couldn't get
> the accumulate syntax right.  Anyone know of a way to do
> that? (I figure that would get a "pure rules"
> solution.)
> 
> 
> --- On Sat, 11/7/09, Wishing Carebear <wishing.carebear at gmail.com>
> wrote:
> 
> > From: Wishing Carebear <wishing.carebear at gmail.com>
> 
> > Subject: [rules-users] some pointers for solution
> > To: rules-users at lists.jboss.org
> > Date: Saturday, November 7, 2009, 10:19 PM
> 
> 
> 
> > Hello:
> > There are n selection criteria from s1 .. sn for each
> > item i1.. in. Each item can have a subset of criteria
> which
> > applies to them.
> >  
> > The end user, can choose a subset of criteria like c1
> 
> > and c5 and only the item that has c1 and c5 valid
> should be
> > returned. For example: if item i1 and i2 have
> criterias
> > valid for c1, c2, c5, c6, c8 since the request is only
> for
> > criteria c1 and c5, i1 and i2 must be returned.
> 
> >
> >  
> > Is it possible to write a rule using drools for this
> > requirement.
> >  
> > Thanks for your help and time,
> > cabear
> >
> > -----Inline Attachment Follows-----
> 
> >
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> > rules-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> 
> >
> 
> 
>      
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