Trouble testing if on-the-fly generated checkboxes are checked

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

I basically learned Perl by altering existing scripts (yeah, not the best, I know). I need to generate multiple unique checkboxes in an HTML page, then see if any of them have been checked.

The whole little testing script is below. If I check for simple checkedness, ie, "if ($value)", nothing shows as checked. Likewise for "if ($value eq 'on')" (or any string, or number). If I try "if ($value == 'any damn string')" EVERTHING is on.

I suspect the problem is actually how I am getting the form parameters into the $form_data array, which is a piece of apparent magic from the original script I started with and seems to have worked fine for all the other field types in the actual real cgi program.

The script can be run from http://www.toukleyartgallery.com.au/cgi-bin/checktest.htm

#!/usr/bin/perl -w

BEGIN { open (STDERR, ">test.err");}

use CGI qw(:standard);
use CGI::Carp qw/fatalsToBrowser/;

$ENV{"PATH"} = "";

print "Content-type: text/html\n\n";

$query = new CGI;
foreach $sparam ($query->param())
{
    $form_data{$sparam} = $query->param($sparam);
}

&check_test;

sub check_test()
{
    print qq~
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http:/
+/www.w3.org/TR/html4/loose.dtd">
<html>
<head>
</head>
<body>
~;
    print "<form name='form1' method='post' action='http://www.toukley
+artgallery.com.au/cgi-bin/checktest.cgi'>\n";
    for $i (1 .. 4)
    {
        for $j (1 .. 4)
        {
            if ($form_data{'box$i$j'} == "definitely not on")
            {
                print "<font color='#FF0000'>Box $i$j:  $form_data{'bo
+x$i$j'}</font> ";
            }
            else
            {
                print "Box $i$j: <input type='checkbox' name='box$i$j'
+>  "
            }
        }
    }
    print "\n<input type='submit' name='Submit' value='Submit'>\n</for
+m>\n";
    print "</body>\n</html>\n";
}
[download]

Comment on Trouble testing if on-the-fly generated checkboxes are checked Download Code

Replies are listed 'Best First'.
Re: Trouble testing if on-the-fly generated checkboxes are checked by Your Mother (Archbishop) on Jun 06, 2018 at 04:46 UTC
Without checking your code, just going on your post– `perl -le 'print "YUM!" if "tamales" == "rellenos"' YUM!` [download] `==` forces numeric comparison which forces both string sides to zero, making them equal. Update: I should have said, use `eq` instead for string equality comparisons.	[reply] [d/l] [select]
Re: Trouble testing if on-the-fly generated checkboxes are checked by bliako (Abbot) on Jun 06, 2018 at 09:49 UTC
From CGI man page : `my @values = $q->multi_param('foo');` -or- `my $value = $q->param('foo');` -or- `my @values = $q->param('foo'); # list context, discouraged and will ra +ise # a warning (use ->multi_param instead)` [download] Pass the param() method a single argument to fetch the value of the named parameter. If the parameter is multivalued (e.g. from multiple selections in a scrolling list), you can ask to receive an array. Otherwise the method will return a single value. ----------------- Maybe your `$form_data{"box$i$j"}` contained an array (edit: it is not correct, it will contain the length of the array) as returned by param($sparam}) in list content, whereas the `param("box$i$j") eq "string"` was forced to return a scalar, i.e. a single string. If that's the case you have some more debugging to do. In that case, `use strict; use warnings;` [download] at the beginning of your program will be your friends.	[reply] [d/l] [select]
Re: Trouble testing if on-the-fly generated checkboxes are checked by goldgryph (Initiate) on Jun 06, 2018 at 02:55 UTC
I've also tried explicitly passing the value "on" back in the <checkbox> tag. Same results.	[reply]
Re^2: Trouble testing if on-the-fly generated checkboxes are checked by poj (Abbot) on Jun 06, 2018 at 06:46 UTC
Single quotes do not interpolate `# if ($form_data{'box$i$j'} == "definitely not on") if ($form_data{"box$i$j"} eq "on")` [download] Read more... (1100 Bytes) poj	[reply] [d/l] [select]
Re: Trouble testing if on-the-fly generated checkboxes are checked by goldgryph (Initiate) on Jun 06, 2018 at 07:26 UTC
Thanks guys, already tried all variations of eq and ==, single and double quotes (which was a problem, but not the main one). I discovered that using param("box$i$j") actually did the trick.	[reply]