It gets more strange!
 
I had already tried your first suggestion and that didn't fix it.
 
However, I have three other rules that do essentially the same thing but on different object classes - the object classes are very similar however.
 
When I removed the insert statement from the first rule (the one mentioned below) replacing it with just a system.out.println, then the other rules all fire successfully and their insert statements work fine.
 
So I thought it must be something strange with the UtranCell class.
 
But then I tried your second suggestion - modifying only the first rule  and that worked great. So I made the same update to the other rules - now the same problem is happening to another rule that had been working perfectly.
 
So then I tried playing around with the rule salience of each of the rules and it turns out that the rule which is run last is the one that fails. If I change salience to make a different rule run last then that rule fails with the exception - otherwise it works fine!
 
Very weird!
 

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Swindells, Thomas
Sent: 19 March 2010 10:57
To: Rules Users List
Subject: Re: [rules-users] Exception during insert

Odd,

 

Looks like it is a problem in the internal of mvel, there’s two things I’d suggest you could try:

Firstly try change it to be something similar to:

for (int i=0; i<ucells.length; i++)

{

UnltranCell toInsert = ucells[i];
                insert( toInsert );

      }

If you are lucky this may sort out the type inference.

 

The other option is to try rewriting the rule to be more declarative and not have the iteration.  This can be achieved by inserting the UtranCell array as a global (cells) and then having a rule where the when part similar to “$cell : UltranCell() from cells” and a then part which inserts the single cell returned into the knowledge base.

 

Thomas

 

From: rules-users-bounces@lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Ryan Fitzgerald
Sent: 19 March 2010 10:40
To: rules-users@lists.jboss.org
Subject: Re: [rules-users] Exception during insert

 

**Apologies if this post starts a new thread**

 

 

Hi Thomas,

 

I get a series of com.sample.UtranCell strings printed expected.

 

So the array seems to be correctly comprised of UtranCell objects.

 

I have the following import statement in the drl file:

 

import com.sample.UtranCell;

 

Weird!

 

/Ryan.

 

 

From: rules-users-boun...@lists.jboss.org
[mailto:rules-users-boun...@lists.jboss.org] On Behalf Of Ryan Fitzgerald
Sent: 19 March 2010 09:41
To: rules-users@lists.jboss.org
Subject: [rules-users] Exception during insert

Hi,

I get the following exception when trying to insert an object from within a
rule consequence:

[Error: object is not an instance of declaring class]

The rule is as follows:

rule "Utran Cell Selection Rule"
salience 50
dialect "java"
        when
        then
                UtranCell[] ucells =
TopologyService.getInstance().getUtranCells();
                for (int i=0; i<ucells.length; i++) {
                insert( ucells[i] );
                }
end


And it works fine if I replace the insert with System.out.println(ucells[i]) -
it seems to be something problematic with the insert. Full trace is below.

I can't see what the problem is...any ideas?

Thanks,
Ryan.

org.drools.runtime.rule.ConsequenceException: [Error: object is not an instance
of declaring class]
[Near : {... Unknown ....}]
             ^
[Line: 1, Column: 0]
        at
org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:23)
        at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:943)
        at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:885)
        at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1086)
        at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:660)
        at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:627)
        at
org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:183)
        at com.sample.DroolsTest.main(DroolsTest.java:28)
Caused by: [Error: object is not an instance of declaring class]
[Near : {... Unknown ....}]
             ^
[Line: 1, Column: 0]
        at
org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:389)
        at
org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:138)
        at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:133)
        at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85)
        at
org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:104)
        at org.mvel2.MVEL.executeExpression(MVEL.java:995)
        at
org.drools.base.dataproviders.MVELDataProvider.getResults(MVELDataProvider.java:91)
        at org.drools.reteoo.FromNode.evaluateAndPropagate(FromNode.java:124)
        at org.drools.reteoo.FromNode.assertLeftTuple(FromNode.java:104)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:117)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:28)
        at org.drools.reteoo.JoinNode.assertLeftTuple(JoinNode.java:116)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:117)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:28)
        at org.drools.reteoo.JoinNode.assertLeftTuple(JoinNode.java:116)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:117)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:28)
        at org.drools.reteoo.JoinNode.assertLeftTuple(JoinNode.java:116)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:117)
        at
org.drools.reteoo.SingleLeftTupleSinkAdapter.createAndPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:78)
        at
org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:142)
        at
org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:42)
        at
org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:185)
        at
org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:146)
        at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1046)
        at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1001)
        at
org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:114)
        at
org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:108)
        at
com.sample.Rule_Utran_Cell_Selection_Rule_0.consequence(Rule_Utran_Cell_Selection_Rule_0.java:9)
        at
com.sample.Rule_Utran_Cell_Selection_Rule_0ConsequenceInvoker.evaluate(Rule_Utran_Cell_Selection_Rule_0ConsequenceInvoker.java:18)
        at
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:934)
        ... 6 more
Caused by: java.lang.IllegalArgumentException: object is not an instance of
declaring class
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at
org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:931)
        at
org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:316)
        ... 36 more

 

 



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