Re: Template Loaders and Acquisition Mechanism

Thursday, October 8, 2009, 3:25:15 PM, Darko Radosevic wrote:

> Hi,
>
> we have templates placed in folder hierarchy (default/client/site)
> and we're using default FileTemplateLoader and acquisition mechanism
> to load templates. But now we want to introduce a brand new type of
> templates - templates for mobile site. The mobile templates should
> follow this same default/client/site hierarchy but they should take
> precedence over regular templates when the request is coming from a
> mobile device. We could diferrentiate mobile templates by placing in
> separate folder or by "m_" name prefix, we haven't decided yet. So,
> loading order on a mobile site should be:
>
> 1. mobile site template 2.mobile client 3 mobile default 4.standard
> site 5 standard client 6.standard default
>
> This looks tricky to solve, I've first tried to utilize
> MultiTemplateLoader and some custom TemplateLoaders, but I would get only this loading order:
>
> 1. mobile site 2.standard site 3.mobile client 4. standard client
> 5. mobile default 6.standard default.
>
> The only working solution I've found so far is to use two
> Configurations,

Don't do that, it's not how Configurations meant to be used. Templates
returned by one of the Configuration-s will search their dependences
using that Configuration. This also means that you will end up some
templates cached twice... and who knows what else I didn't realized
right now.

> each having different base folder. In case 'mobile'
> Configuration throws FileNotFoundException, try to use 'standard'
> Configuration. The problem with this solution is that we'll need
> copy all templates from the 'standard' folder to the 'mobile' folder and then maintain duplicates.
>
> The only other possible solution I see is to rewrite TemplateCache
> to maybe somehow  move acquisition mechanism inside template loader,
> but this looks way too low-level...

You couldn't even do that there in a way so it will work correctly.

> Do you know of any cases where TemplateCache is overwritten with
> some diferrent implementation, or do you know of some Freemarker
> features that could be useful for me?

Maybe you can do the trick with the localization feature... like if
being mobile optimized would be a locale variation (you know, the
optional 3rd part of the locale string). Localization quite much does
what you need, in that it first tries to find the most locale-specific
template variation with acquisition, and only when that fails tries it
to find a less-specific one.

Now if it doesn't work out well with localization, you can still
submit a patch. But then let's see what should be achieved... you want
to specify the target *media* here. It's very much like localization
right now, so it should look similarly: [email protected],
mytemplate_@mobile_en.ftl, mytemplate_@mobile_en_US.ftl, etc. It's @
because that's also what CSS uses for media selection, and it's also
suggestive: the page "at a mobile", "at a printer". I think the media
should have higher priority than locale, and that's also what you
wanted here. If a different need arises, we can still add a
media_priority setting. Yeah, and target_media itself is a new
setting. Pretty much like locale.

Objections?

Of course, you may ask for some guidance if you want to do the patch.

> Thanks,
> Darko

-- 
Best regards,
 Daniel Dekany


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