<div dir="ltr">Hi guys,<div>I was writing some rules using backward chaining and found a strange behavior. </div><div>I managed to isolate the error in the test project I'm attaching. </div><div><br></div><div>In the project I have 2 classes: Parent and Child</div>
<div><br></div><div>Parent:</div><div> * String id</div><div> * String attribute1</div><div> * String attribute2</div><div> * List<Child> children</div><div><br></div><div>Child:</div><div> * String parentId;</div>
<div> * String name;</div><div> * String value;</div><div><br></div><div><br></div><div>In the test I'm creating 1 Parent object with just 1 child and then inserting the Parent object into a drools session:</div>
<div><br></div><div><div> Parent p1 = new Parent();</div><div> p1.setId("1");</div><div> p1.setAttribute1("a1");</div><div> p1.setAttribute2(null);</div><div> </div>
<div>
Child c1p1 = new Child();</div><div> c1p1.setName("n1");</div><div> c1p1.setParentId(p1.getId());</div><div> c1p1.setValue("v1.1");</div><div> p1.addChild(c1p1);</div>
<div> </div><div> kSession.insert(p1);</div><div> kSession.fireAllRules();</div></div><div><br></div><div><br></div><div>So far so good. </div><div>The rules I have in my session are the following:</div>
<div><br></div><div><div>declare Parent</div><div> @propertyReactive</div><div>end</div><div><br></div><div>query getChildWithName(String $parentId, String $name, Child $child)</div><div> $child:= Child(parentId == $parentId, name == $name)</div>
<div>end</div><div><br></div><div>rule "Insert Children"</div><div>when</div><div> $p: Parent() @watch(!*)</div><div> $c: Child() from $p.children</div><div>then</div><div> System.out.println("Inserting child "+$c);</div>
<div> insert($c);</div><div>end</div><div><br></div><div>rule "Rule A"</div><div>when</div><div> $p: Parent(attribute2 != null)</div><div> ?getChildWithName($p.attribute2, "n1", $child;)</div>
<div>then</div><div> System.out.println("FOUND: "+$child+". The attribute 'parentId' of this object must have the value '"+$p.getAttribute2()+"'. Does it? "+$child.getParentId()+" == "+$p.getAttribute2()+" ??");</div>
<div> globalList.add($child);</div><div>end</div><div><br></div><div><br></div><div>rule "Copy Attribute1 into Attribute2"</div><div>when</div><div> $p: Parent(attribute1 != null, attribute2 == null)</div>
<div>then</div><div> modify($p){</div><div> setAttribute2($p.getAttribute1())</div><div> }</div><div>end</div></div><div><br></div><div>The important part here is 'Rule A' and 'Copy Attribute1 into Attribute2'. The latter copies the value of attribute1 to attribute2 for any Parent object present in the session. (Note that the parent I'm inserting has attribute2 = null). 'Rule A' is then using a query to get a Child object that has a parent with id = $p.attribute2 (where $p is a previously matched Parent).</div>
<div>Given that I only have 1 Parent in my session and that its id is '1' I don't expect 'Rule A' to be activated/executed. When I modify parent.attribute2 in 'Copy Attribute1 into Attribute2' I'm setting its value to 'a1'. 'Rule A' (via the query) should then look for a Child with parentid = 'a1' and It shouldn't find anything. </div>
<div>Funny thing is that 'Rule A' activates and fires. The child object that is 'returned' by the query has a parentId of '1' so I don't know how this behavior is possible. If you take a look at the System.out output you will see that the activation makes no sense at all.</div>
<div><br></div><div>Am I doing something wrong in my project? Is this a bug? Is this the expected behavior?</div><div><br></div><div>Regards,</div><div><br></div><div><br clear="all"><div><br>XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX<br>
<br>Esteban Aliverti<br>- Blog @ <a href="http://ilesteban.wordpress.com" target="_blank">http://ilesteban.wordpress.com</a></div>
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