You can indeed do what you are asking, I am currently doing this.
Just build an object or a "tool" with the following method.
Here is what I put into my velocity macro to test it...
$vsesstool is a tool that I created (see the docs...)
Tony
#set ($myExpr = '$row.getColumn("pl_product_line_description")')
$myExpr
$vsesstool.evalExpression($data,$myExpr)
public static String evalExpression (RunData data, String expression) {
Context context = TurbineVelocity.getContext(data);
StringBuffer content = new StringBuffer();
BufferedReader in = null;
try {
/* this approach makes use of the oreilly.jar file */
in = new BufferedReader(new StringReader(expression));
StringWriter writer = new StringWriter();
Velocity.evaluate(context, writer, "INFO", in);
content.append(writer.toString());
}
catch (Exception e) {
// something went wrong
}
finally {
if (in != null) {
try {
in.close();
}
catch (Exception e) {
// something else went wrong
}
}
}
return content.toString();
}
-----Original Message-----
From: news [mailto:[EMAIL PROTECTED] On Behalf Of BoD
Sent: Wednesday, March 29, 2006 11:15 AM
To: [email protected]
Subject: Re: Expression evaluation inside a template?
Thank you for your answer.
I'm not sure I was completely clear so I'll give a more precise example
of what I'm trying to do.
Let's say I have a tool that has a method createObject().
This method returns an object that has a getProp() method returning
"hello".
The tool also has a method getExpression() returning the string
"$obj.getProp()".
I'm trying to make a velocimacro that given this:
#set ($obj = $myTool.createObject())
#set ($expr = $myTool.getExpression())
#myMacro($expr)
Would generate this:
hello
So I would need something like eval($expr) that would evaluate the
content of $expr which is $obj.getProp(). Obj being declared before it
would call the method and return "hello".
I have no idea on how to create such a macro or if it is possible.
Thank you very much for your help.
BoD
Tony Oslund a écrit :
> If you read the Velocity docs you will find that it encourages you to
> access methods on your objects rather than trying to access a property
> directly.
>
> Try doing $x.getValue(), or $y.doSomething() rather than attempting to
> do x.myalue.
>
> Along the same lines, if you are tempted to use arrays, use an ArrayList
> with Velocity instead.
>
> It is possible to access a method on an object within a Velocity
> template that in turn returns the contents of another velocity template,
> and so on and so on. I currently use this to handle language
> translation, managed content, and also reusable sections of web pages.
>
> If you are truly looking for expression evaluation. There is an open
> source java library called beanshell. It allows you to eval a java
> expression. I have used it behind the scenes to perform Boolean
> evaluation of string expressions like {X} or {Y} and not {Z}, etc. It
> works very well.
>
> -----Original Message-----
> From: news [mailto:[EMAIL PROTECTED] On Behalf Of BoD
> Sent: Wednesday, March 29, 2006 8:56 AM
> To: [email protected]
> Subject: Expression evaluation inside a template?
>
> Hi!
>
> In a template, is there a way to evaluate a Velocity expression inside a
>
> variable ?
> For example, let's say I have set in a Java screen a variable "expr"
> with the value "$myObj.prop" in the context.
>
> Now I'd like to evaluate the expression represented by $expr when I'm in
>
> the template. Is there any way to do that, something like eval($expr)?
>
> Thank you very much for your help!
>
> BoD
>
>
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