[jboss-jira] [JBoss JIRA] (DROOLS-664) Implement xpath notation in drools constraints

[Mario Fusco (JIRA)]

     [ https://issues.jboss.org/browse/DROOLS-664?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mario Fusco closed DROOLS-664.
------------------------------
    Fix Version/s: 6.4.0.Final
       Resolution: Done


> Implement xpath notation in drools constraints
> ----------------------------------------------
>
>                 Key: DROOLS-664
>                 URL: https://issues.jboss.org/browse/DROOLS-664
>             Project: Drools
>          Issue Type: Feature Request
>            Reporter: Mario Fusco
>            Assignee: Mario Fusco
>             Fix For: 6.4.0.Final
>
>
> It is required to allow an xpath notation in drools constraints like the following:
> {code}
> Person( $pet : /pets ) 
> {code}
> that is formally equivalent to the more verbose:
> {code}
> Person( $pets : pets )
> $pet : Pet() from $pets
> {code}
> It should be also possible to have conditions filtering the collection like in:
> {code}
> Person( $pet : /pets[ age == 5 ] )
> {code}
> corresponding to:
> {code}
> Person( $pets : pets )
> $pet : Pet(age == 5) from $pets
> {code}
> Of course also multiple indirections has to be allowed, so the following:
> {code}
> Man( $toy : /wife/children/toys )
> {code}
> will be equivalent to:
> {code}
> $man: Man( $wife: wife )
> $child: Child() from $wife.children
> $toy: Toy() from $child.toys
> {code}
> In this case the xpath notation will also allow to flatten the 2 from nodes in a single one that will internally flatten the collection of collections. Since it is necessary to distinguish the case when we want to iterate a collection from the case when we want to bind the collection as a whole it is possible to mix the collection iteration operator '/' and the simple dereferencing operator '.' as in:
> {code}
> Man( $toys : /wife/children.toys )
> {code}
> In this last case this pattern binds each List<Toy> for each child as a whole, so this is equivalent to:
> {code}
> $man: Man( $wife: wife )
> Child( $toys: toys ) from $wife.children
> {code}



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