Re: Java constants in Freemarker template

Saturday, March 29, 2008, 3:16:14 PM, Sunil wrote:

> Hi,
> Iam developing a portlet application in which Freemarker templates we are
> using for View.
>
> Iam trying to use the constants present in Java class file in the freemarker
> templates. I have the read the posts which says that we can use java constants
> in the Freemarker templates by using the following commands.
>
> ${stack.findValue("@fully.classified.classname@constantName")}

That may works like that under a sepcific Web Application Framework
(Struts, I guess), but not in general.

> But, When Iam trying to access the constants in my template file using the
> above command, Iam getting the below freemarker exception.
>
> freemarker.core.InvalidReferenceException: Expression stack in undefined.
>
> can any one please let me know whats wrong here and how can we access 
> constants present in Java class/Interface file in the Freemarker template file.

So, the thing is that the Web Application Framework + the application
specific Controller parts has full control over what's visible in the
data-model, thus the static constants of Java classes will not be
there automatically; someone has to put it there. An easy way is
putting the result of yourBeansWrapper.getStaticModels() into the
data-model (or to make that object accessible by other means, like
with an FTL library). If you put it into the data-model with "statics"
name (just an example), then you could write this in the template:
${statics[fully.classified.classname].constantName}. Also, you can
expose the static entries of only a single class if you put the result
of BeansWrapper.getStaticModels().get("fully.classified.classname")
into the data-model. With a similar trick you can expose JDK5 enums as
well, with yourBeansWrapper.getEnumModels().

Note 1: yourBeansWrapper should be just the ObjectWrapper that the
freemarker.tempalte.Configuration object uses. If you can't access
that, you can still use BeansWrapper.getDefaultInstance() for this
purpose.

Note 2: You can easily add something to all data-models at once by
using yourConfiguration.setSharedVariable(name, value) during
application initialization.

> Thanks,
> Sunil.


-- 
Best regards,
 Daniel Dekany


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