Passing variables in PSGI

TheChosenOne has asked for the wisdom of the Perl Monks concerning the following question:

I've got a CGI script that I want to convert to PSGI. This is the result:

    use CGI::Emulate::PSGI;
    use strict;
    use warnings;
    use CGI qw(:cgi-lib :standard);
    use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
    
    my $q = new CGI;
    
    my @keys = param();
    
    my $state = "";
    if(scalar @keys > 0){
        $state = $keys[0];
    }
    
    my $app = CGI::Emulate::PSGI->handler(sub {
        @keys = $q->param();
        print $q->header;
        print "<center>";
        print $q->h1('Some title');
        print "</center>";
        print $q->start_html(-title => 'Some title');
        print $keys[0];
        home();
        sub home{
            print "<center>";
            print $q->h3('Pick an option.');
            print $q->end_form;
            print "</center>";
            print "<center>";
            my $q0 = new CGI;
            print $q0->start_form(
                -name    => 'some_button',
                -method  => 'POST',
                -enctype => &CGI::URL_ENCODED,
            );
            print $q0->submit(
                -name     => 'click_me',
                -value    => 'Do something',
            );
            print $q0->end_form;
            print "</center>";
        }
        print $q->end_form;
    });
[download]

After I click on 'Do something', I return to the same page (obviously), but it should print 'click_me'. This worked in CGI, but for some reason PSGI doesn't pass this variable. I can print other variables that are defined above. So my @keys = param(); doesn't seem to do a whole lot. Edit: Apparently PSGI uses %ENV, but I can't make it work with POST. It works with GET.

Edit: The solution is actually very easy. 'Your Mother' has the solution. I knew that you could compile your CGI scripts and emulate them. But if your run a perl server (like plackup), you get the next error: plackup: Variable "$variable" is not available at /location/of/script." The solution is to change the permissions of all global variables from 'my' to 'our'.

Comment on Passing variables in PSGI Download Code

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Re: Passing variables in PSGI by Your Mother (Archbishop) on Sep 08, 2014 at 15:39 UTC
You declare your CGI (well, one of them) outside your handler and your handler has a nested named sub. Nesting named subs typical doesn’t work the way you think. Instead of trying to untangle it I would just recycle your CGI script verbatim and change the psgi code to look like this (CGI::Compile and CGI::Emulate::PSGI). `my $sub = CGI::Compile->compile("/path/to/YOUR-SCRIPT.cgi"); my $app = CGI::Emulate::PSGI->handler($sub);` [download]	[reply] [d/l]
Re: Passing variables in PSGI by Anonymous Monk on Sep 09, 2014 at 00:26 UTC
Remember the comments from Manually add parameters in perl cgi? especially Re: Manually add parameters in perl cgi ( no ReadParse no CGI->Vars? #!/usr/bin/perl -- ## ## ## ## perltidy -olq -csc -csci=3 -cscl="sub : BEGIN END " -otr -opr -ce +-nibc -i=4 -pt=0 "-nsak=" ## perltidy -olq -csc -csci=10 -cscl="sub : BEGIN END if " -otr -opr +-ce -nibc -i=4 -pt=0 "-nsak=" #!/usr/bin/perl -- use strict; use warnings; use CGI (); use CGI::Carp qw(warningsToBrowser fatalsToBrowser); Main( @ARGV ); exit( 0 ); sub Main { #~ return DebugCGI(); #~ return RootPage(); return ToPsgi(); } ## end sub Main sub ToPsgi { my $sub = CGI::Compile->compile( __FILE__ ); my $app = CGI::Emulate::PSGI->handler( $sub ); return $app; } ## end sub ToPsgi sub RootPage { my $q = CGI->new; print $q->header, RootTemplate( $q ); } ## end sub RootPage sub RootTemplate { my( $q ) = @_; my @keys = $q->param(); print $q->header; print "<center>"; print $q->h1( 'Some title' ); print "</center>"; print $q->start_html( -title => 'Some title' ); print $keys[0]; print SomePage(); print $q->end_form; } ## end sub RootTemplate sub SomePage { my $q = shift \|\| CGI->new( {} ); my $ret = join "\n", "<center>", $q->h3( 'Pick an option.' ), $q->end_form, "</center>", "<center +>", $q->start_form( -name => 'some_button', -method => 'POST', -enctype => &CGI::URL_ENCODED, ), $q->submit( -name => 'click_me', -value => 'Do something', ), $q->end_form, "</center>", ; return $ret; } ## end sub SomePage sub DebugCGI { my $cgi = CGI->new; binmode STDOUT, ':encoding(UTF-8)'; $cgi->charset( 'UTF-8' ); print $cgi->header( -charset => 'UTF-8' ); print $cgi->start_html, $cgi->b( rand time, ' ', scalar gmtime ), '<table border="1" width="%100"><tr><td>', $cgi->Dump, '</td>', '<td><div style="white-space: pre-wrap; overflow: scroll;">', $cgi->escapeHTML( DD( $cgi ) ), '</div></td></tr></table>', CGI->new( \%ENV )->Dump, $cgi->end_html; } ## end sub DebugCGI sub DD { require Data::Dumper; return scalar Data::Dumper->new( \@_ )->Indent( 1 )->Useqq( 1 )->D +ump; } ## end sub DD [download]	[reply] [d/l]
Re: Passing variables in PSGI by sundialsvc4 (Abbot) on Sep 09, 2014 at 00:40 UTC
Also consider using Plack, specifically Plack::Handler::CGI and Plack::App::WrapCGI. There is “much goodness” here which might save you a lot of time when doing this.


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