in reply to [SOLVED] Unwanted parameter when executing CGI scripts

Now, when calling such scripts without any parameters (i.e. without query string after the script name / path), the scripts are seeing an unwanted parameter "Keywords" (which does not have a value).

Trivial to test 

$ perl -MData::Dump -MCGI -e " dd( CGI->new(q{?noampernoequal}) )"
bless({
  ".charset"     => "ISO-8859-1",
  ".fieldnames"  => {},
  ".parameters"  => ["keywords"],
  "escape"       => 1,
  "param"        => { keywords => ["?noampernoequal"] },
  "use_tempfile" => 1,
}, "CGI")

$ perl -MCGI -e " print CGI->new(q{?noampernoequal})->param "
keywords
$ perl -MCGI -e " print CGI->new(q{?noampernoequal})->keywords "
?noampernoequal
$ perl -MCGI -e " print for CGI->new(q{?noampernoequal})->keywords "
?noampernoequal
$ perl -MCGI -e " print for CGI->new(q{?a=b;noampernoequal})->keywords
+ "

[download]

Easy to remove 

use Data::Dump;
use CGI;
my $q = CGI->new( q{?noampernoequal});
dd $q;
dd $q->param;
dd $q->keywords;
$q->delete('keywords') if $q->keywords;
dd $q->param;
dd $q;
__END__
bless({
  ".charset"     => "ISO-8859-1",
  ".fieldnames"  => {},
  ".parameters"  => ["keywords"],
  "escape"       => 1,
  "param"        => { keywords => ["?noampernoequal"] },
  "use_tempfile" => 1,
}, "CGI")
"keywords"
"?noampernoequal"
()
bless({
  ".charset"     => "ISO-8859-1",
  ".fieldnames"  => {},
  ".parameters"  => [],
  "escape"       => 1,
  "param"        => {},
  "use_tempfile" => 1,
}, "CGI")

[download]

I don't think I've ever used this feature in 10 years :)

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Re^2: Unwanted parameter when executing CGI scripts
by Nocturnus (Scribe) on Jan 05, 2013 at 08:01 UTC

    Well, I think that

    $q->delete('keywords') if $q->keywords;

    will delete the "keywords" parameter in every case, i.e. regardless if it has been automatically generated by CGI.pm or if it actually has been passed via query string. But as I wrote in my initial post, I would like to remove it only in the former case (for example when the script has been called without any parameters), but I want to keep it if it has been "actively" passed via query string.

    Thus, I think I really have to check if there is no query string, or if there is a query string which does not contain = or &, and remove the "keywords" parameter accordingly.

    Anyways, thank you very much for your suggestion. I have learned a much from how you use dd and Data::Dump.

    Regards,

    Nocturnus

[reply]
[d/l]

      will delete the "keywords" parameter in every case, i.e. regardless if it has been automatically generated by CGI.pm

      You're wrong :)

      I didn't read past that statement, but if you need convincing you are wrong, read the CGI.pm source

[reply]
[reply]

        OK, I am sorry. You are right (no need to read the source code, only the documentation ...).

        Interestingly, the delete method seems to remove the respective entry only from $q->params, but not from $q->url_params (now guess which of the two I (have to) use). This is not documented in the CGI.pm documentation as far as I have seen.

        But that's not a big problem. I just will use one of the usual methods to remove the respective hash entry.

        Besides this, I didn't get your code to work like I want. Perhaps I have another error, but at the moment it seems that $q->keywords is empty if the script is called without any parameters, so $q -> keywords evaluates to false in this case, and the code doesn't get executed anyways.

        Regards,

        Nocturnus

[reply]

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