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Date: Thu, 8 Dec 2016 20:08:58 +0000 (UTC)
From: "Claus Ibsen (JIRA)" <jira@apache.org>
To: issues@camel.apache.org
Message-ID: <JIRA.13026653.1481197675000.476527.1481227738515@Atlassian.JIRA>
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Subject: [jira] [Updated] (CAMEL-10572) RefLanguage should support
 Predicates for Choice
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archived-at: Thu, 08 Dec 2016 20:09:00 -0000


     [ https://issues.apache.org/jira/browse/CAMEL-10572?page=3Dcom.atlassi=
an.jira.plugin.system.issuetabpanels:all-tabpanel ]

Claus Ibsen updated CAMEL-10572:
--------------------------------
    Estimated Complexity: Novice  (was: Unknown)

> RefLanguage should support Predicates for Choice
> ------------------------------------------------
>
>                 Key: CAMEL-10572
>                 URL: https://issues.apache.org/jira/browse/CAMEL-10572
>             Project: Camel
>          Issue Type: Improvement
>          Components: camel-core
>    Affects Versions: 2.18.1
>            Reporter: Christoph L=C3=A4ubrich
>            Priority: Minor
>             Fix For: 2.19.0
>
>
> The documentation for the CBR (http://camel.apache.org/content-based-rout=
er.html) states=20
> {quote}The following example shows how to route ... depending on the eval=
uation of various Predicate expressions{quote}
> If you now look at the predicate section (http://camel.apache.org/predica=
te.html) it says:
> {quote}Camel supports extensible Predicates using multiple Languages; the=
 following languages are supported out of the box
> ...
> Ref Language
> ...{quote}But going to the Ref page (http://camel.apache.org/ref-language=
.html) it states{quote}The Ref Expression Language is really just a way to =
lookup a custom Expression from the Registry. {quote}
> So Ref Language does NOT support Predicates, it works in most cases since=
 nearly all classes in Camel core implement Expresion and Predicate interfa=
ce and there is a lot of converting between those, but if you have a custom=
 expression that only implements predicate, you get in fact an (a bit misle=
ading) exception:
> {quote}java.lang.IllegalArgumentException: Cannot find expression in regi=
stry with ref: predicate
> =09at org.apache.camel.language.ref.RefLanguage$1.evaluate(RefLanguage.ja=
va:50)
> =09at org.apache.camel.support.ExpressionAdapter.evaluate(ExpressionAdapt=
er.java:36)
> =09at org.apache.camel.support.ExpressionSupport.matches(ExpressionSuppor=
t.java:32)
> =09at org.apache.camel.util.ExpressionToPredicateAdapter.matches(Expressi=
onToPredicateAdapter.java:35)
> =09at org.apache.camel.processor.FilterProcessor.matches(FilterProcessor.=
java:65)
> =09at org.apache.camel.processor.ChoiceProcessor.process(ChoiceProcessor.=
java:93)
> =09at org.apache.camel.management.InstrumentationProcessor.process(Instru=
mentationProcessor.java:77)
> =09at org.apache.camel.processor.RedeliveryErrorHandler.process(Redeliver=
yErrorHandler.java:542)
> =09at org.apache.camel.processor.CamelInternalProcessor.process(CamelInte=
rnalProcessor.java:197)
> =09at org.apache.camel.processor.CamelInternalProcessor.process(CamelInte=
rnalProcessor.java:197)
> =09at org.apache.camel.component.timer.TimerConsumer.sendTimerExchange(Ti=
merConsumer.java:192)
> =09at org.apache.camel.component.timer.TimerConsumer$1.run(TimerConsumer.=
java:76){quote}
> It takes me some time to find out that Camel is in fact finding my bean b=
ut can't use it, beside that its hard to work out why a predicate must also=
 implement expression (Choice it self requires an Predicate in fact, so it =
converts all expresions to Predicates).
> So the following improvements would be nice
> # Let RefLanguage send out some kind of TypeConverterException if it can'=
t use the bean as the desired type
> # Let Ref, if it finds that the referenced bean is a predicate, convert t=
his to an expression e.g with PredicateToExpressionAdapter


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