Returning only content-type header from LedgerSMB::Template - devel

31 Aug 2017

With the idea to simplify our LedgerSMB::Template handler, by moving all
headers (but the content-type) from there to LedgerSMB::PSGI, I went to
task:

In the referenced issue, you write
...

 The template should be responsible *only* to render the content and
 provide a file mime type back with it. This means that the output of
 template->render() should ...

 Assuming that "template" there corresponds to my definition of
 "LedgerSMB Template Engine" (concluded from the fragment of the second
 sentence), I really wonder what value the template engine is providing: our
 template processor has a render method too; the *only* thing it lacks is
 the content type return value. The content type can be easily added based
 on the extension of the processed template in a generic handler elsewhere
 though.

 Right.

 In the same paragraph, you continue

 The Template MUST NOT assume HTTP, PSGI, or any other particular
 input/output format.

 Could you have a look and https://github.com/ledgersmb/L
 edgerSMB/blob/master/lib/LedgerSMB/Template.pm#L540 ? I think that that
 achieves what you want.

 Yes, though more specifically, I think if we *do not use* PSGI or output
 options we achieve something much better.  What I want to achieve is a
 clearer separation of responsibility and I think this has cascading
 benefits through the rest of the application as well as making the logic
 more general.

 Ok. You're proposing the return value being a pair: the expanded template
 and the mime-type. The current implementation is a list of headers (usually
 just the mime-type), the expanded template and a success/fail indicator (a
 triplet).

 If we want to go with just the pair, how are we going to report the
 success/fail indicator? (In other words, how do we report error
 conditions?) I'll move the handling of the cache control headers currently
 in "render_to_psgi()" to LedgerSMB::PSGI. That's a positive outcome of
this
 discussion for sure.

I have local work-in-progress. I've successfully moved the characterset
addition to (utf-8) to all "text/" mime-types as well as the headers
disabling caching when "back button disabling" is enabled, to
LedgerSMB::PSGI.

However, I'm trying to move the Content-Disposition headers to
LedgerSMB::PSGI, but that's not quite so easy: the disposition header uses
knowledge from the template (the type and name of the report). This
information is not available on the LedgerSMB::PSGI level. So, how do I
meaningfully name the downloaded file in this new world order?

Regards,

-- 
Bye,

Erik.

http://efficito.com -- Hosted accounting and ERP.
Robust and Flexible. No vendor lock-in.