Upgrading to JUEL 2.1.1 - Beware of API changes in JUEL
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Key: CAMEL-1567
URL: https://issues.apache.org/activemq/browse/CAMEL-1567
Project: Apache Camel
Issue Type: Task
Components: camel-juel
Affects Versions: 2.0-M1, 1.6.0
Reporter: Claus Ibsen
Hi Claus,
Here is an explanation of the API change from Christopher Beck at JUEL:
Hello Yogesh,
the API to resolve methods has changed in 2.1.1. Camel's method resolver
is breaks with JUEL 2.1.1. Generally, methods are still resolved via
ELResolver.getValue(context, base, property), but
- in 2.1.0, the method name was passed as a property
- in 2.1.1, an instance of de.odysseus.el.misc.MethodInvocation is passed
as a property
The reason for this is to provide more detailed information about the
method invocation to the resolver (i.e the method name, number of arguments
and whether vararg calls are supported).
Now, camel-juel uses its BeanAndMethodELResolver to resolve methods.
There, findMethod(context, base, property) only handles a property
parameter of type string. That's why it doesn't work. When migrating to
juel 2.1.1, the BeanAndMethodELResolver class needs to be updated to work
with MethodInvocation objects as properties.
The JUEL 2.1.1 distribution contains a sample resolver. Taking the sample
code, updating camel's resolver should be pretty straightforward. When
doing so, you may also want to add property "javax.el.varArgs" in
JuelExpression.populateDefaultExpressionProperties(..). That way you would
take real profit by invoking vararg methods from within EL expressions.
There's also a way to quickly modify your resolver to work with both, JUEL
2.1.0 and 2.1.1. Just don't ask for "property instanceof String" but use
property.toString() as a candidate method name: the MethodInvocation's
toString() will answer the method name.
See nabble:
http://www.nabble.com/Camel-JUEL-expression-weirdness-in-1.6.0-td23177119s22882.html
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