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From "James Strachan" <james_strac...@yahoo.co.uk>
Subject Re: [jelly] 'bug' setting tag properties from properties file
Date Tue, 17 Dec 2002 14:16:30 GMT
From: <dion@multitask.com.au>
> Background:
> I'm using the latka plugin.
> It has a set of Jelly tags which have Strings for their setter methods,
> i.e. the Request tag has a setHost(String) method.
>
> Problem:
> 1) I populate these tags with an expression, which references properties
> maven reads from project.properties, e.g.
>
> <suite defaultHost="${latka.host}">
>
> where latka.host is defined in the ${basedir}/project.properties
>
> 2) When the tag is executed, I get a
> 2002-12-17 13:29:52,798 DEBUG org.apache.commons.jelly.impl.TagScript -
> Caught exception: java.lang.IllegalArgumentException: Property
> 'defaultHost' has no write method
> java.lang.IllegalArgumentException: Property 'defaultHost' has no write
> method
>
> 3) This is caused because the expression is being passed to BeanUtils with
> no conversion done, e.g. :
> 2002-12-17 13:29:52,758 DEBUG org.apache.commons.jelly.JellyContext -
> findVariable: latka.host value:
>
org.apache.commons.jelly.expression.ConstantExpression@502819[value=DEV270]
> 2002-12-17 13:29:52,758 DEBUG org.apache.commons.beanutils.BeanUtils -
> setProperty(org.apache.commons.latka.jelly.SuiteTag@78aa80, defaultHost,
>
org.apache.commons.jelly.expression.ConstantExpression@502819[value=DEV270])
>
> 4) This tag has no methods that take an Expression as a paramter, and
> since no conversion is being done by Jelly/BeanUtils the code fails with
> the above IllegalArgumentException.
>
> 5) When these properties are passed in from the command prompt via
> -Dlatka.host=DEV270 for example, all works fine, as they are explicitly
> known as Strings.

TagScript already tries to evaluate any Expression objects before they are
set on properties on Tags. Maybe in this case we have multiply-nested
expressions inside Maven's JellyContext implementation? i.e. that an
expression evaluates to another expression, which when it evaluates the
final value is a String.

<aside>
Maybe when the variable scopes are introduced into Jelly this might fix any
errors like this that are introduced by Maven's JellyContext implementation.
</aside>

A workaround could be to patch TagScript to use the
expression.evaluateRecurse() rather than the expression.evaluate() methods?
I don't have time right now to investigate this but if you fancy having a
try, I've attached the patch to TagScript to do exactly this.

James
-------
http://radio.weblogs.com/0112098/

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