Inadvertant type conversion while using keyword "in"
by TroyL
We ran into an issue when evaluating string values against a list of values
while using the keyword "in".
We find that when there is a decimal place in the string value and either
the fact inserted into the session or the string values in the list end with
a zero, the string will be truncated, as if it were being type converted
from a string to an int.
As as example: Fact type "Test"
package com.sample;
public class Test {
private String code;
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
}
Sample DRL:
package com.sample
//Test code value == "1.5"
rule "Incorrect Execution"
when
Test($code : code in ("1.50"))
then
System.out.println("Unexpected execution: 1.50, 2.50 - actual code
value: 1.5");
end
//Test code Value == "1.5"
rule "Correct Execution"
when
Test(code == "1.5")
then
System.out.println("Expected execution - Code compared values: 1.5,
2.5 - actual code value: 1.5");
end
We insert a "Test" fact into the session with a code value of 1.5. The
output is as follows:
Unexpected execution: 1.50, 2.50 - actual code value: 1.5
correct execution - Code compared values: 1.5, 2.5 - actual code value: 1.5
Drools Expert documentation states:
Type coercion is always attempted if the field and the value are of
different types; exceptions will be thrown if a bad coercion is attempted.
For instance, if "ten" is provided as a string in a numeric evaluator, an
exception is thrown, whereas "10" would coerce to a numeric 10. Coercion is
always in favor of the field type and not the value type:
Both evaluators are actually syntactic sugar, internally rewritten as a list
of multiple restrictions using the operators != and ==.
Is there some way to disable the auto-conversion feature?
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14 years, 8 months
Re: [rules-users] string replace collision problem
by FrankVhh
Cautionç This is answered after only a quick look.
You must notify the engie that a change has occured by calling update(plan);
in the RHS. Not calling update will modify the object, but the engine will
not take these changes into account.
Regards,
Frank
fiitkar wrote:
>
> Hello,
>
> I've problem with string replacement.
> See the following example.
> Input string: SF
> I've written two simple rules:
> The first one transforms SF to S
> The second one transforms S to VOL.
> The expected output after the transformation should be S, but I get VOL.
> (as for example for the rules: A->Z, Z->K, input A, output will be Z and
> not K).
> So my question is how to avoid this problem (I suppose the problem is that
> the first transformation returns substring of the input and moreover does
> exist another transformation rule for it).
>
> rule "Rule1 for parameter 1"
> salience 2
> when
> plan : plan( parameter1 matches ".*SF.*" )
> then
> plan.setParameter1(plan.getParameter1().replace("SF","S"));
>
> end
>
>
> rule "Rule2 for parameter 1"
> salience 1
> when
> plan : plan( parameter1 matches ".*S.*" )
> then
> plan.setParameter1(plan.getParameter1().replace("S","VOL"));
> end
>
> Thank you for your response.
> Peter
>
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14 years, 8 months
loading rules and drools classes via URLClassLoader
by ukriegel
Hi there,
we tried to use drools jars from an url:
1. define an URLClassLoader with all the urls of the necessary drools jars
in the search path.
2. initialize a KnowledgeBaseConfiguration with that class loader
KnowledgeBaseConfiguration knowledgeBaseCfg = KnowledgeBaseFactory
.newKnowledgeBaseConfiguration(null, dcURLClassLoader);
3. initialize a KnowledgeBase with that configuration
KnowledgeBase kbase = KnowledgeBaseFactory
.newKnowledgeBase(knowledgeBaseCfg);
4. initialize a KnowledgeBuilderConfiguration with that class loader
KnowledgeBuilderConfiguration knowledgeBuilderCfg =
KnowledgeBuilderFactory
.newKnowledgeBuilderConfiguration(null, dcURLClassLoader);
5. initalize a knowledge builder
kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder(kbase,
knowledgeBuilderCfg);
6. adding a knowledge resource to that builder results in a
org.drools.RuntimeDroolsException "Unable to load dialect
org.drools.rule.builder.dialect.java.JavaDialectConfiguration:java" if the
drools jars are not in the start class path.
Did we something wrong or uses drools while adding ressources a classloader
different from that given in the configuration?.
Thanks in advance
Ulrich
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14 years, 8 months
Drools server => get a query result
by jcp
Hi, i'm new to drools so excuse me if i'm asking newbie question.
For a project I insert via rest service a list of object to drools server,
in a stateless session - no need to use a stateful session.
The rules are fired and new objects are inserted.
ex :
rule "1"
when
$c : condition()
then
insert(new FiredRule("my rule 1 fired", $c))
end
I also have a query who gets all the FiredRule
query "get fired rules"
firedRule : FiredRule()
end
My problem is that i can't get results from query when i'm in stateless
mode.
It works in stateful mode, but I need drools to work only with object I send
via rest service at time t. I don't want them store in in the knowledge base
and be reused for a future request.
I'm block here.
I send via json the batch-execution command with "insert-elements" and
"query" => "name":"get fired rules","out-identifier":"rules"
and I have an Exception when I set an out-identifier to "fire-all-rules"
11:26:00,552 ERROR [DefaultErrorHandler] Failed delivery for exchangeId:
949a5873-d146-4ad3-bc9c-d0dd9f7bbc81. Exhausted after delivery attempt: 1
caught: java.lang.NullPointerException
java.lang.NullPointerException
at
org.drools.command.runtime.rule.FireAllRulesCommand.execute(FireAllRulesCommand.java:110)
at
org.drools.command.runtime.rule.FireAllRulesCommand.execute(FireAllRulesCommand.java:32)
at
org.drools.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:155)
at
org.drools.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:76)
at
org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:265)
at
org.drools.camel.component.DroolsExecuteProducer.process(DroolsExecuteProducer.java:100)
When I test my case with java, I can get my query results, so I am led to
think that it is a problem on server side, maybe jars in the lib???
Or is it impossible to set an out-identifier for fire-all-rules in stateless
mode?.
Another consideration were to dispose each knowledgesession (on stateful
mode) when I send request to drools, but there is no command to do that,
only stop/restart server???
Subsidiary question : is it possible to add a System.out.println() in my
query??If yes, how to do it?
Thank you for your help
JC
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14 years, 8 months
Operation of "otherwise" in Decision Table (Guided editor) of Guvnor
by Manohar Kokkula
Hi All,
I am new to Guvnor,
Please can any one explain me the uses of "otherwise" in Decision
table(Guided editor) with simple example ?
Thanks and regards
Manohar Kokkula
Mailto: manohar.kokkula(a)tcs.com
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14 years, 8 months
No rules loaded when reading package from Guvnor
by sgo
Hello all,
I'm a semi-beginner with Drools and am having an issue I haven't found
reported elsewhere.
I have a package defined in Guvnor, with model imported from JAR, one
global, a dozen rules and a couple of test scenarios. The package is loaded
from the binary published by Guvnor via a knowledge agent into my stateless
session (defined in Spring beans), but no rules ever fire. (Note that rules
do fire as expected in my Guvnor test scenarios.) When investigating in
debug mode, I see the package is properly loaded, with imported type
definitions and global, but no rule is in there! The package's rules table
is empty and I really have no clue why (I initially thought my rule
definitions could be the cause and created a minimal test package with just
one simple rule but with no success.)
Could anyone point to possible causes for this?
Many thanks in advance.
Simon
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14 years, 8 months
How to handle generics in Drools?
by Martin A
Hello,
In my rules file I'd like to set something like this:
rule "mayThrowDice"
when
$user : User($gp : gameplay)
$gameplay(this == $gp)
then
exists List<Boost>() {
..... some business logic
}
end
But it looks like there is no generics support. How can I make sure there is
a List of type Boost inserted into the session?
Thank you,
Martin
14 years, 8 months
drools stateful session, cluster and replication
by Rules
>From the documentation i understand that statefulknowledge session can be
persisted.
Can we also replicate the session/working memory across servers and still be
able to maintain the integrity of facts and rete tree ?
Is there a way i could replicate asserted facts incrementally or do i have
to replicate the entire session each time (i consume events from external
systems that could bring in new facts and alter existing facts) ?
I am considering an app server provided replication that uses multi
casting/uni casting and i will have a lot of data in working memory, around
3 GB. what are my options if i want to replicate it across cluster ?
Appreciate any help...
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14 years, 8 months
