12:49 p.m.
Hi All,
I'm trying to call a class method from the LHS of a rule in the following
way:
public class Cheese{
private string type;
//setters and getters
public boolean existsInShop(String shop){
...
return true;
}
}
I would like to call the method "existsInShop" from a rule:
Rule "Rule1"
when
$c:Cheese(type == "chedar", existsInShop "shopName")
then
System.out.println("Rule1 is fired");
end
I get the compilation error: "no viable alternative at input "shopName" in
rule "Rule1" in pattern document". How can I call the method from the
rule?
Thanks in advance.
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1:39 p.m.
What you need is called "inline eval expression" (see the Drools Expert
manual),
or an eval conditional element. The first one might be written as:
$c:Cheese(type == "chedar", eval( this.existsInShop("shopName") ) )
-W
On Mon, Jan 4, 2010 at 12:49 PM, orchid <maya.pollack(a)gmail.com> wrote:
Hi All,
I'm trying to call a class method from the LHS of a rule in the following
way:
public class Cheese{
private string type;
//setters and getters
public boolean existsInShop(String shop){
...
return true;
}
}
I would like to call the method "existsInShop" from a rule:
Rule "Rule1"
when
$c:Cheese(type == "chedar", existsInShop "shopName")
then
System.out.println("Rule1 is fired");
end
I get the compilation error: "no viable alternative at input "shopName"
in
rule "Rule1" in pattern document". How can I call the method from the
rule?
Thanks in advance.
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2:25 p.m.
Using Wolfgang's inline eval epression, I get the following error: "Cannot
use this in a static context" when compiling the rule. I changed
"this" by "$c" and it works. I don't know why we are in a static
context.
The rule that worked for me is:
Rule "Rule1"
when
$c:Cheese(type == "chedar", eval($c.existsInShop ("shopName"))
then
System.out.println("Rule1 is fired");
end
I attached a working test case. Change $c to "*this" *in rule's condition
and you will see the error I mentioned.
Best,
2010/1/4 Wolfgang Laun <wolfgang.laun(a)gmail.com>
What you need is called "inline eval expression" (see the
Drools Expert
manual),
or an eval conditional element. The first one might be written as:
$c:Cheese(type == "chedar", eval( this.existsInShop("shopName") ) )
-W
On Mon, Jan 4, 2010 at 12:49 PM, orchid <maya.pollack(a)gmail.com> wrote:
>
> Hi All,
>
> I'm trying to call a class method from the LHS of a rule in the following
> way:
>
> public class Cheese{
> private string type;
> //setters and getters
> public boolean existsInShop(String shop){
> ...
> return true;
> }
> }
>
> I would like to call the method "existsInShop" from a rule:
>
> Rule "Rule1"
> when
> $c:Cheese(type == "chedar", existsInShop "shopName")
> then
> System.out.println("Rule1 is fired");
> end
>
> I get the compilation error: "no viable alternative at input
"shopName" in
> rule "Rule1" in pattern document". How can I call the method from the
> rule?
>
> Thanks in advance.
>
>
>
> --
> View this message in context:
> http://n3.nabble.com/Call-class-method-from-LHS-of-a-rule-tp108383p108383...
> Sent from the Drools - User mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
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Esteban Aliverti
2:35 p.m.
Esteban and Wolfgang, thank you very much !!!
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1:58 p.m.
This doesn't work because it not reference anything inside the eval,
remember that inside the eval you must write an expression that will
be compiled and evaluated in runtime.
- Ing. Mauricio Salatino -
On Jan 4, 2010, at 11:35 AM, orchid <maya.pollack(a)gmail.com> wrote:
Esteban and Wolfgang, thank you very much !!!
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3:39 p.m.
2010/1/4 Esteban Aliverti <esteban.aliverti(a)gmail.com>
Using Wolfgang's inline eval epression, I get the following
error: "Cannot
use this in a static context" when compiling the rule. I changed
"this" by "$c" and it works. I don't know why we are in a static
context.
Strange. Most likely the compiler converts the inline eval to an eval CE,
where you can't have "this".
I have occasionally used s.th. like
$foo : Foo( $bar : bar )
Bar( this == $bar )
which goaded me into thinking that this.method() should work in an inline
eval.
Thanks for checking this, though!
-W
The rule that worked for me is:
Rule "Rule1"
when
$c:Cheese(type == "chedar", eval($c.existsInShop ("shopName"))
then
System.out.println("Rule1 is fired");
end
I attached a working test case. Change $c to "*this" *in rule's condition
and you will see the error I mentioned.
Best,
2010/1/4 Wolfgang Laun <wolfgang.laun(a)gmail.com>
> What you need is called "inline eval expression" (see the Drools Expert
> manual),
> or an eval conditional element. The first one might be written as:
>
> $c:Cheese(type == "chedar", eval( this.existsInShop("shopName") )
)
>
> -W
>
>
>
> On Mon, Jan 4, 2010 at 12:49 PM, orchid <maya.pollack(a)gmail.com> wrote:
>
>>
>> Hi All,
>>
>> I'm trying to call a class method from the LHS of a rule in the following
>> way:
>>
>> public class Cheese{
>> private string type;
>> //setters and getters
>> public boolean existsInShop(String shop){
>> ...
>> return true;
>> }
>> }
>>
>> I would like to call the method "existsInShop" from a rule:
>>
>> Rule "Rule1"
>> when
>> $c:Cheese(type == "chedar", existsInShop "shopName")
>> then
>> System.out.println("Rule1 is fired");
>> end
>>
>> I get the compilation error: "no viable alternative at input
"shopName"
>> in
>> rule "Rule1" in pattern document". How can I call the method from
the
>> rule?
>>
>> Thanks in advance.
>>
>>
>>
>> --
>> View this message in context:
>> http://n3.nabble.com/Call-class-method-from-LHS-of-a-rule-tp108383p108383...
>> Sent from the Drools - User mailing list archive at Nabble.com.
>> _______________________________________________
>> rules-users mailing list
>> rules-users(a)lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>>
>
>
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
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1:54 p.m.
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@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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2:11 p.m.
/* pass a hibernate session to the working memory as a global */
session = factory.openSession();
workingMemory.setGlobal("hibernateSession", session);
Login login = new Login();
workingMemory.insert(login);
the isssue was that i was doing it the wrong way that was
Login login = new Login();
workingMemory.insert(login);
/* pass a hibernate session to the working memory as a global */
session = factory.openSession();
workingMemory.setGlobal("hibernateSession", session);
the order was wrong
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5146
days inactive
5226
days old
7 comments
5 participants
participants (5)
-
Esteban Aliverti -
HafeezurRehman -
orchid -
Salaboy -
Wolfgang Laun