[rules-users] Collecting properties in a rule

[Michael Anstis]

Thanks Wolfgang, quite how I missed the "collect" in my DRL I don't know :(

2011/11/14 Wolfgang Laun <wolfgang.laun at gmail.com>

> The rule below assumes that markets is List<Market> in Town and ids is
> List<Integer> in a Market.
>
> It does not rely on Market or even Location objects being facts, and
> there's no problem if a location id is re-used in another town.
>
> rule findThree
> when
>     $t: Town( $name: name, $markets: markets )
>     $s: HashSet( $size: size ==3 )
>             from accumulate( $m: Market() from $markets,
>                              init( HashSet set = new HashSet(); )
>                              action( set.addAll( $m.getIds() ); )
>                              result( set ) )
> then
>     System.out.println( $name + " is a three-location town " + $s );
> end
>
>
>
> 2011/11/14 Michael Anstis <michael.anstis at gmail.com>
>
>> 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!
>>>
>>> --
>>> View this message in context:
>>> http://drools.46999.n3.nabble.com/Collecting-properties-in-a-rule-tp3503523p3503523.html
>>> Sent from the Drools: User forum mailing list archive at Nabble.com.
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>>
>>
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