[rules-users] Collecting properties in a rule

[Michael Anstis]

Something like this?

when
    $t : Town( )
    $s : SuperMarket( town == $t, $lid : locationId )
    $ls : HashSet( size == 3) from ( Location( locationId = $lid ) )

I suspect Location would have to override equals and hashCode correctly.

Once you have some DRL that works I'd suggest moving to Guvnor.

On 12 November 2011 23:15, LCode <j_whittlesea at hotmail.com> wrote:

> I am trying to write a rule via the guided rule editor and I am really
> struggling.
>
> The following is a simplified explanation of my scenario:
>
> I have a model where there are lots of 'Town' objects, each town has any
> number of 'Supermarket' objects and each supermarket has a list of integers
> 'locationID'.
>
> Something like this....
>
>        <Town>
>                <Supermarket name = 'asda'>
>                        <LocationID>15</LocationID>
>                        <LocationID>18</LocationID>
>                </Supermarket>
>                <Supermarket name = 'tesco'>
>                        <LocationID>13</LocationID>
>                </Supermarket>
>                <Supermarket name = 'lidl'>
>                        <LocationID>13</LocationID>
>                        <LocationID>15</LocationID>
>                        <LocationID>18</LocationID>
>                </Supermarket>
>        </Town>
>
> (apologies to the Sainsburys shoppers!!)
>
> I need to write a rule that fires when there are precisely 3 unique
> location
> ID's in the whole town.
>
> So in the example above the complete list of locationIDs would be 13, 13,
> 15, 15, 18, 18
> With the following unique numbers 13, 15, 18
> therefore the rule would fire as there are 3 unique numbers.
>
> I hope that makes some sense.
>
> I understand that I should collect the locationIDs into a java.util.Set in
> order to count unique entries and I can collect together all supermarkets
> into an arraylist. However I cannot for the life of me seem to collect
> LocationID across all supermarkets.
>
> Thank you so much in anticipation, I realise this was rather long-winded!
>
> --
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