Plack::Middleware::Conditional - Conditional wrapper for Plack middleware

       Tatsuhiko Miyagawa

       Steve Cook

       Plack::Middleware::Conditional is a piece of meta-middleware, to run a specific middleware component
       under runtime conditions. The goal of this middleware is to avoid baking runtime configuration options in
       individual middleware components, and rather share them as another middleware component.

       Note that some of the middleware component names are just made up for the explanation and might not
       exist.

         # Minify JavaScript if the browser is Firefox
         enable_if { $_[0]->{HTTP_USER_AGENT} =~ /Firefox/ } 'JavaScriptMinifier';

         # Enable Stacktrace when being accessed from the local network
         enable_if { $_[0]->{REMOTE_ADDR} =~ /^10\.0\.1\.*/ } 'StackTrace';

         # Work with other conditional setter middleware:
         # Transcode Jpeg on the fly for mobile clients
         builder {
             enable 'MobileDetector';
             enable_if { $_[0]->{'plack.mobile_detected'} }
               'TranscodeJpeg', max_size => 30_000;
             $app;
         };

       Note that in the last example MobileDetector should come first because the conditional check runs in pre-run conditions, which is from outer to inner: that is, from the top to the bottom in the Builder DSL
       code.

       Plack::Middleware::Conditional - Conditional wrapper for Plack middleware

       Plack::Builder

perl v5.38.2                                       2024-01-20                Plack::Middleware::Conditional(3pm)

         use Plack::Builder;

         builder {
             enable_if { $_[0]->{REMOTE_ADDR} eq '127.0.0.1' } 'StackTrace', force => 1;
             $app;
         };

         # or using the OO interface:
         $app = Plack::Middleware::Conditional->wrap(
             $app,
             condition  => sub { $_[0]->{REMOTE_ADDR} eq '127.0.0.1' },
             builder => sub { Plack::Middleware::StackTrace->wrap($_[0], force => 1) },
         );