Re: CGI::Tiny versus undefined parameter/form field

It's pretty straightforward to construct an SSCCE showing this working just fine both with the specified parameter and without:

$ cat foo.cgi
#!/usr/bin/env perl
use strict;
use warnings;
use CGI::Tiny;

cgi {
    my $cgi = $_;
    my $bookparam = $cgi->param('book') || '';
    $cgi->render (text => "bookparam is $bookparam\n");
}
$ (export QUERY_STRING='book=bar'; ./foo.cgi)
Date: Mon, 12 Dec 2022 13:57:29 GMT
Content-Type: text/plain;charset=UTF-8
Content-Length: 17

bookparam is bar
$ ./foo.cgi 
Date: Mon, 12 Dec 2022 14:01:26 GMT
Content-Type: text/plain;charset=UTF-8
Content-Length: 14

bookparam is 
$
[download]

As others have suggested, it seems that your $cgi is undefined. The error is in the code you haven't shown us.

🦛

Comment on Re: CGI::Tiny versus undefined parameter/form field Select or Download Code

Replies are listed 'Best First'.
Re^2: CGI::Tiny versus undefined parameter/form field by Polyglot (Chaplain) on Dec 12, 2022 at 15:16 UTC
Thank you. I didn't try that code yet, but I noticed something in it that differed from mine. You have this line... `my $bookparam = $cgi->param('book') \|\| '';` ...inside the `cgi { ... }` codeblock. I have "$cgi->param()" calls scattered across a multitude of subroutines, as each subroutine needs to deal with a particular set of form inputs. What is to be done if those only work inside that single code block? This would operate in a way that differed fundamentally from standard CGI. With CGI, I was able to create the "object," then use it throughout the script. It seems this may be the problem. Blessings, ~Polyglot~	[reply] [d/l] [select]
Re^3: CGI::Tiny versus undefined parameter/form field by pryrt (Abbot) on Dec 12, 2022 at 15:31 UTC
...inside the cgi { ... } codeblock. I have "$cgi->param()" calls scattered across a multitude of subroutines Per the CGI::Tiny documentation, that $cgi object is only valid inside the `cgi { ... }` codeblock. "There is no CGI::Tiny object constructor; the object is accessible within the cgi block, only reads request data from the environment once it is accessed, and ensures that a valid response is rendered to avoid gateway errors even in the event of an exception or premature exit." You might be able to rework it so that the code in the `cgi {...}` block is calling all your subroutines, and you pass the $cgi object as an argument to each of those subroutines, but that may be a lot of refactoring. As I said, if you're really looking for a drop-in replacement for CGI.pm, where you can use the $cgi object throughout your code with the same syntax you are used to from CGI.pm, you will likely want to use something like CGI::Simple instead of CGI::Tiny.	[reply] [d/l] [select]
Re^3: CGI::Tiny versus undefined parameter/form field by hippo (Archbishop) on Dec 12, 2022 at 16:32 UTC
This would operate in a way that differed fundamentally from standard CGI. Of course. And the documentation goes to some lengths to explain this. Perhaps you have not read it yet? 🦛	[reply]
Re^4: CGI::Tiny versus undefined parameter/form field by Polyglot (Chaplain) on Dec 12, 2022 at 16:54 UTC
I do, naturally, have the very same difficulty with understanding abstractions in documentation as I have with them in actual code. I scanned the documentation for parts that I thought I could understand, and did not look closely at the rest. Obviously, I had mistaken the module for being a compatible replacement to CGI. It isn't, and therefore is not suited to my needs. It reminds me a little of an AJAX module I once incorporated into my scripts. It worked for awhile, until I discovered it was occasionally doing something unpredictable, and altering my data during transfers--resulting in errors in the database. That's when I learned to program the AJAX for myself, and kicked the module to the proverbial curb, never to be needed again (and those errors have not recurred). I often find the need to do things myself, as what others have done is not compatible. I doubt I am alone in this. Blessings, ~Polyglot~	[reply]
Re^3: CGI::Tiny versus undefined parameter/form field by tybalt89 (Monsignor) on Dec 12, 2022 at 19:09 UTC
Just put all the calls to those multitude of subroutines inside the `cgi` block and switch to `our` :) `#!/usr/bin/perl use strict; # https://perlmonks.org/?node_id=11148743 use warnings; use CGI::Tiny; our $cgi; cgi { $cgi = $_; some_sub_somewhere_else(); }; sub some_sub_somewhere_else { my $bookparam = $cgi->param('book') \|\| ''; $cgi->render (text => "bookparam is $bookparam\n"); }` [download]	[reply] [d/l] [select]