in reply to Read JSON data from a form

You seem to be confusing the send and return aspects. You are not sending JSON to the script as the serialize() method serializes a form's data into a query string, not JSON (this string can be decoded using the normal CGI methods). On the other hand, you are telling jQuery that your response will be JSON ( dataType: "json" in your javascript and $q->header("application/json") in your perl script) but you are not sending JSON back, just a plain string.

I don't know your exact requirements but I suspect you don't need to send JSON to your script, you may however need to return JSON. This may help you to see the difference:

Javascript

<script type="text/javascript" >
$(function() {
    $(".submit").click(function() {
        var formData = $("#reply-form").serialize();
        alert(formData);
    
        $.ajax({
            type: "post",
            url: "code.pl",
            cache: false,
            data: formData,
            dataType: "json",
            success: function(data) //onSuccess,
            {
                alert(data.calling_params);
            },
            error: function()
            {
                alert( "Sorry, there was a problem!" );
            }
        });
        return false;
    });
});
</script>

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Perl

use strict;
use warnings;

use CGI;
use JSON;
use Data::Dumper;

my $q = new CGI;
my $in = $q->Vars;
my $string = Dumper ($in);
my $response = encode_json( { calling_params => "$string" } );

print $q->header("application/json");
print $response;

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Replies are listed 'Best First'.
Re^2: Read JSON data from a form
by Anonymous Monk on Dec 29, 2013 at 21:42 UTC
    use CGI->param not CGI->Vars , CGI->Vars has caveats
[reply]
      You are right, but I didn't know the names of the parameters at the time of writing. I can now see those from OP's reply so you could change the offending line to: 
      my $in;
$in->{'name'} = $q->param('name');
$in->{'email'} = $q->param('email');
# etc

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[reply]
[d/l]
        FWIW, you don't need to know the name, param without args provides the names , Vars mangles (encodes, serializes, packs, implodes) the data, its backwards compatibility for some 1993 stuff 
        #!/usr/bin/perl --
use Data::Dump qw/ dd /;
use CGI;
my $q = CGI->new(q{a=b;a=c;d=e;f=g});
my %Vars = map { $_ => [ $q->param($_) ] } $q->param(); 
dd( $q );
dd( $q->Vars );
dd( \%Vars );
__END__
__END__
bless({
  ".charset"     => "ISO-8859-1",
  ".fieldnames"  => {},
  ".parameters"  => ["a", "d", "f"],
  "escape"       => 1,
  "param"        => { a => ["b", "c"], d => ["e"], f => ["g"] },
  "use_tempfile" => 1,
}, "CGI")
("a", "b\0c", "d" .. "g")
{ a => ["b", "c"], d => ["e"], f => ["g"] }



bless({
  ".charset"     => "ISO-8859-1",
  ".fieldnames"  => {},
  ".parameters"  => ["a", "d", "f"],
  "escape"       => 1,
  "param"        => { a => ["b", "c"], d => ["e"], f => ["g"] },
  "use_tempfile" => 1,
}, "CGI")

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        #!/usr/bin/perl --
use Data::Dump qw/ dd /;
use CGI;
my $q = CGI->new(q{a=b;a=c%00d;d=e;f=g});
my %Vars = map { $_ => [ $q->param($_) ] } $q->param();
dd( $q );
dd( $q->Vars );
dd( \%Vars );
__END__
bless({
  ".charset"     => "ISO-8859-1",
  ".fieldnames"  => {},
  ".parameters"  => ["a", "d", "f"],
  "escape"       => 1,
  "param"        => { a => ["b", "c\0d"], d => ["e"], f => ["g"] },
  "use_tempfile" => 1,
}, "CGI")
("a", "b\0c\0d", "d" .. "g")
{ a => ["b", "c\0d"], d => ["e"], f => ["g"] }

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