[rules-users] How to count number of facts of a type in memory?

[puja nandamuri]

Wolfgang

I tried both using collect and accumulate and they both worked as you suggested.

     ArrayList( $total : size>0 ) from collect ( Asset())
   
   Number ($total:intValue ) from accumulate ($asset:Asset() ,count($asset))  

Thanks,

Ram






--- On Sat, 9/3/11, Wolfgang Laun <wolfgang.laun at gmail.com> wrote:

From: Wolfgang Laun <wolfgang.laun at gmail.com>
Subject: Re: [rules-users] How to count number of facts of a type in memory?
To: "Rules Users List" <rules-users at lists.jboss.org>
Date: Saturday, September 3, 2011, 9:47 PM

2011/9/4 puja nandamuri <med_9501 at yahoo.com>
>
> I tried to create the following rule using a simple drl to just count the number of Asset facts in memory.
> An Asset can be a very simple class. I am not sure if the fields or methods are really relevant in this rule.
>
> rule " Count number of Assets Rule"
> dialect "mvel"
> when
> asset:Asset()
> ArrayList($total:size >0)  from collect ( asset)

The first operand of collect is a pattern, not a bound variable. Therefore, use

    ArrayList($total:size >0)  from collect ( Asset() )

Just for counting, accumulate would also be possible:

   Number( $total: intValue ) from accumulate( Assert(), count(1) )

-W


> then
> System.out.println(" Number of Assets in memory"+total);
> end
> This fails. my understanding of how collect works seems to be wrong :(
> can you please correct the mistake I might be doing here ?
>
>

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