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https://issues.apache.org/struts/browse/WW-2807?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=46148#action_46148
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Christopher Schultz commented on WW-2807:
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Sorry to be a pain, but I'm having some real trouble getting Velocity to even
work with s2 in the first place.
After finally getting Velocity working in the first place (had some trouble:
http://www.nabble.com/-s2--Difficulty-using-Velocity-with-Struts-2-td23316915.html)
I can't properly translate the "blank" webapp's HelloWorld example into
Velocity.
I'm just trying to re-create the HelloWorld.jsp in Velocity and it's not clear
/at all/ how to translate the tags. All the documentation I can find says "just
change the <% to # and you're good to go!" which seems to be a fallacy.
My first attempt yielded:
#surl('id=url' "action=HelloWorld")
#sparam('name=request_locale')en#end
#end
...which doesn't work because apparently these tags don't have end-tags. If
they don't have end-tags, then how do they include content?
So, I changed my URL to the simplest thing I could think of:
<a href="#surl("id=url" "action=HelloWorld" )">English</a>
This doesn't work, either. I get a blank URL. Duh! the <s:url> tag doesn't
output anything: it just defines a variable. Okay, I'll do:
#surl('id=url' "action=HelloWorld")
<a href="$url">English</a>
...but how do I get a parameter as part of my URL? Should I be doing this:
$link.setRelative($url).addQueryData('request_locale', 'en')
($link is a tool provided by Velocity to build URLs so you don't have to worry
about where the ? and & characters go).
It looks like I can move forward, but it doesn't look like s2 is very friendly
towards Velocity. :(
> Improve Velocity tag syntax and performance
> -------------------------------------------
>
> Key: WW-2807
> URL: https://issues.apache.org/struts/browse/WW-2807
> Project: Struts 2
> Issue Type: Improvement
> Affects Versions: 2.0.0, 2.0.1, 2.0.2, 2.0.3, 2.0.4, 2.0.5, 2.0.6, 2.0.7,
> 2.0.8, 2.0.9, 2.0.10, 2.0.11, 2.0.11.1, 2.0.11.2, 2.0.12, 2.1.0, 2.1.1,
> 2.1.2, 2.1.3, 2.1.4, 2.2.x, Future
> Environment: Apache Velocity 1.5+
> Reporter: Christopher Schultz
> Priority: Minor
> Fix For: 2.1.8
>
>
> Currently, Velocity "tags" are implemented by passing a number of
> "name=value" strings to S2's Velocity tag implementation in order to pass
> named parameters (which are not directly supported by Velocity). This leads
> to a somewhat awkward syntax and requires that the tag implementation
> re-parse these strings for every template evaluation, loop execution, etc.
> Starting with Velocity 1.5, template authors can create Map objects on the
> fly using a simple syntax. I believe that supporting this syntax in the
> Velocity S2 integration code will make templates easier to read and run more
> quickly.
> Example of current Velocity tag usage (this is the example from
> http://struts.apache.org/2.0.11.2/docs/velocity-tags.html):
> #sform ("action=updatePerson")
> #stextfield ("label=First name" "name=firstName")
> #ssubmit ("value=Update")
> #end
> The new, proposed syntax would be this:
> #sform({'action' : 'updatePerson' })
> #stextfield({'label' : 'First name', 'name' : 'firstName'})
> #ssubmit({'value' = 'Update'})
> #end
> The tag implementation has change from supporting an unknown number of
> unnamed string parameters to accepting a single Map parameter containing
> name/value pairs. S2's code will no longer hand to parse each of the string
> parameters into their separate name and value, and should therefore run
> faster.
> It also allows template designers to use single-quote syntax for their
> parameter names (single-quoted strings are never interpreted) and either
> double-quote syntax for their values (which /will/ interpret their contents)
> or pass the objects directly (possibly as non-String objects). I believe this
> will also increase performance as well as flexibility, since some tags will
> prefer non-String parameters and will no longer be required to parse a String
> unless absolutely necessary.
> Such a change would require one of the following strategies:
> 1. Implement a second Velocity tag library whose tags accept a single Map
> parameter
> 2. Augment the current Velocity tag library to accept /either/ a single Map
> parameter /or/ a series of String values
> I believe #2 would be a better solution: users can choose which syntax they
> prefer and don't have to go through any messy re-configuration steps to
> switch syntax. It also supports legacy users with no changes at all. The only
> downside is that you'd have to restrict any future tags such that they do not
> accept a single Map parameter and then behave differently. I think this is a
> reasonable trade-off.
> I would be happy to submit a sample implementation for one or two tags, but
> I'll probably need help doing /every/ tag.
> Thanks,
> -chris
> Please see the following mailing list threads for reference:
> [struts-dev]
> http://www.nabble.com/-s2--Improved-Velocity-Integration-td19541213.html
> [struts-user] http://www.nabble.com/-S2--Velocity-Integration-td19520425.html
> [velocity-dev] http://www.nabble.com/Named-macro-parameters-td19459070.html
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