[rules-dev] Locating objects by query/BC

[Wolfgang Laun]

I saw a commit and tried again, but the problem is still around.
I added a test to BackwardChainingTest - see the pull request.

-W

On 25 June 2011 14:10, Mark Proctor <mproctor at codehaus.org> wrote:

> **
> I have isolated the issue and know what it is, and why it works one way and
> not the other. In short on unification if the variable is unbound we need to
> turn off indexing for that specific join attempt. We do this when it's left
> triggered, we don't do this when it's right triggered. Updated the code to
> also do this on right triggering. Should have it fixed tonight.
>
> Thanks
>
> Mark
>
> On 25/06/2011 12:38, Mark Proctor wrote:
>
> ok thanks, I reproduced the problem with the following below. If you change
> the String insertion order it works. I'll get this fixed over the weekend:
>     @Test
>     public void testQueryWithObject() throws Exception {
>         String str = "" +
>             "package org.drools.test  \n" +
>
>             "import java.util.List\n" +
>             "import java.util.ArrayList\n" +
>
>             "global List list\n" +
>
>             "dialect \"mvel\"\n" +
>             "\n" +
>
>             "import org.drools.integrationtests.BackwardChainingTest.Q\n" +
>             "import org.drools.integrationtests.BackwardChainingTest.R\n" +
>             "import org.drools.integrationtests.BackwardChainingTest.S\n"
> +
>
>             "query object(Object o)\n" +
>             "    o := Object() \n" +
>             "end\n" +
>
>             "rule collectObjects when\n" +
>             "   String( this == 'go1' )\n" +
>             "   object( o; )\n" +
>             "then\n" +
>             "   list.add( o );\n" +
>             "end\n" +
>
>
>             "rule init when\n" +
>             "   String( this == 'init' )\n" +
>             "then\n" +
>             " insert( new Q(1) );\n " +
>             " insert( new Q(5) );\n " +
>             " insert( new Q(6) );\n " +
>             " insert( new R(1) );\n " +
>             " insert( new R(4) );\n " +
>             " insert( new R(6) );\n " +
>             " insert( new R(2) );\n " +
>             " insert( new S(2) );\n " +
>             " insert( new S(3) );\n " +
>             " insert( new S(6) );\n " +
>             "end\n" +
>             "";
>
>         KnowledgeBuilder kbuilder =
> KnowledgeBuilderFactory.newKnowledgeBuilder();
>         kbuilder.add( ResourceFactory.newByteArrayResource( str.getBytes()
> ),
>                           ResourceType.DRL );
>
>         if ( kbuilder.hasErrors() ) {
>             fail( kbuilder.getErrors().toString() );
>         }
>
>         KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
>         kbase.addKnowledgePackages( kbuilder.getKnowledgePackages() );
>
>         kbase = SerializationHelper.serializeObject( kbase );
>
>         StatefulKnowledgeSession ksession =
> kbase.newStatefulKnowledgeSession();
>         List<Integer> list = new ArrayList<Integer>();
>         ksession.setGlobal( "list", list );
>
>         ksession.insert( "go1" );
>         ksession.fireAllRules();
>
>         ksession.insert( "init" );
>         ksession.fireAllRules();
>
>         System.out.println( list );
>     }
>
> Mark
> On 25/06/2011 11:22, Wolfgang Laun wrote:
>
> // This rule prints all objects in WM.
> rule findObject
> when
>     $o: Object()
> then
>     System.out.println( "Object: " + $o );
> end
>
> Happily I get
>     Object: 42
>     Object: a String object
>     Object: org.drools.reteoo.InitialFactImpl at 4dde85f0
>
> Now the query way:
>     query object( Object o )
>         o := Object()
>     end
>     rule findObjectByQuery
>     when
>         object( $a ; )
>     then
>         System.out.println( "Object by query: " + $a );
>     end
>
> Surprisingly, I get just one:
>     Object by query: org.drools.reteoo.InitialFactImpl at 4dde85f0
>
> A marvellous effect can be observed when the condition in rule
> findObjectByQuery is modified to
>     when
>         Object()
>         object( $a ; )
>     then
> I'd have guessed that the above result would appear repeatedly, once for
> each Object in WM,
> but that's not so. For N-1 facts the rule fires N*(N+1)/2 times, showing
> the "initial object"
> N times, the first inserted object N-1 times, the second one N-2 times and,
> finally, the last one
> once.
> Object by query: 42
> Object by query: org.drools.reteoo.InitialFactImpl at 4dde85f0
> Object by query: a String object
> Object by query: 100
> Object by query: 42
> Object by query: org.drools.reteoo.InitialFactImpl at 4dde85f0
> Object by query: a String object
> Object by query: org.drools.reteoo.InitialFactImpl at 4dde85f0
> Object by query: a String object
> Object by query: org.drools.reteoo.InitialFactImpl at 4dde85f0
>
> -W
>
>
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