[rules-users] Call class method from LHS of a rule

[HafeezurRehman]

I am using hibernate with drools ...


rule "login_validation"
	when
		userRole:UserRole() from hibernateSession.createQuery("select userRoles
from UserAccount ua where ua.name = :name AND ua.password =
:password").setProperties( {"name" : "Hafeez" , "password" : "asdasd"
}).list()
	then
		System.out.println( "--------------------The role " +
userRole.getRoleName()+" is owned by "+userRole.getAccounts());
		
end


this rule is fired and gives me correct userRole.getRoleName()+" is owned by
"+userRole.getAccounts()
Now i want to give dynamic input to LHS.... i.e. I want to replace "Hafeez"
and "asdasd" with some function ...
for the purpose i create a class "LoginAttribs" with "userName" and
"password"

I instert the LoginAttribs loginAttr obj in knowledgebase in A.java


			
WorkingMemory workingMemory = ruleBase.newStatefulSession();
LoginAttribs loginAttr = new LoginAttribs();
workingMemory.insert(loginAttr );


and change the rule in drl file like 

rule "login_validation"
	when
                $lg : LoginAttribs ($uN: userName , $pwd:password)
		userRole:UserRole() from hibernateSession.createQuery("select userRoles
from UserAccount ua where ua.name = :name AND ua.password =
:password").setProperties( {"name" : $uN , "password" : $pwd }).list()
	then
		System.out.println( "--------------------The role " +
userRole.getRoleName()+" is owned by "+userRole.getAccounts());
		
end



And then this comes

Exception caught while executing action:
org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction at 1406eb6
[Error: unable to access property (null parent): createQuery]
[Near : {... Unknown ....}]
             ^
[Line: 1, Column: 0]
	at
org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.getMethod(ReflectiveAccessorOptimizer.java:861)
	at
org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:316)
	at
org.mvel2.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:138)
	at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:133)
	at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85)
	at
org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:107)
	at org.mvel2.MVEL.executeExpression(MVEL.java:995)
	at
org.drools.base.dataproviders.MVELDataProvider.getResults(MVELDataProvider.java:91)
	at org.drools.reteoo.FromNode.evaluateAndPropagate(FromNode.java:124)
	at org.drools.reteoo.FromNode.assertLeftTuple(FromNode.java:104)
	at
org.drools.reteoo.CompositeLeftTupleSinkAdapter.doPropagateAssertLeftTuple(CompositeLeftTupleSinkAdapter.java:145)
	at
org.drools.reteoo.CompositeLeftTupleSinkAdapter.createAndPropagateAssertLeftTuple(CompositeLeftTupleSinkAdapter.java:57)
	at
org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:142)
	at
org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:42)
	at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:185)
	at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:146)
	at org.drools.reteoo.Rete.assertObject(Rete.java:113)
	at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:218)
	at
org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction.execute(ReteooWorkingMemory.java:291)
	at
org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1486)
	at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1051)
	at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1001)
	at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:788)
	
	
	
	
	
	by commenting the insert statement in the java file it works fine
	
	
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