CGI script query

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

I'm currently trying to write some CGI scripts for a website that i'm developing for work. I'm a little new at this, so everything is a 'suck it and see' approach.

Anyway, I've gotten so far, but am stuck on the following. Its a (rather simple) CGI script called from a html form.

#!/usr/bin/perl

use CGI;


my $query= new CGI;

my $pdb_file = $query->param('pdbcode');

print $query->header(-type => 'text/html');

print $query->start_html(-title => "Secondary Structure Analysis");

MainProgram($pdb_file);

$query->end_html( );

#######################################################

# 'main' subroutine

sub MainProgram
{

    my($pdb_file) = @_;
    my $dssp = ".dssp";
    my $dsspdir = "http:/mywebsite/datafiles/";
    my $pdbcode = substr($pdb_file, 0, 4);
    my $dssp_file = "$dsspdir$pdbcode$dssp";

    print $query->('dssp file used is $dssp_file');
 
}
[download]

When I submit data to the preceding form, this script returns a blank page. And when I try running the script from the command line I get the following error

Not a CODE reference at ./script.cgi line 45.

Could anyone please suggest as to what might be going on? Any help much appreciated.

Comment on CGI script query Download Code

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Re: CGI script query by holli (Abbot) on Jun 08, 2005 at 13:43 UTC
Is that all your code? Currently it has only 33 lines, so I am a bit puzzled. Update: The Problem is this line: `print $query->('dssp file used is $dssp_file');` [download] You must replace it with a simple print `print "dssp file used is $dssp_file";` [download] Note the use of double quotes here. With single quotes your variable will not be interpolated. Or use one of the modules output methods. `print $query->h1("dssp file used is $dssp_file");` [download] holli, /regexed monk/	[reply] [d/l] [select]
Re: CGI script query by tlm (Prior) on Jun 08, 2005 at 13:44 UTC
perl is complaining because the syntax `$q->(...)` treats `$q` as a code ref, when it isn't. I'm not sure what you wanted to do with the `$q->(...)` expression, but I think that what you want is simply: `print "dssp file used is $dssp_file<br>";` [download] Note the double quotes, so that you get variable interpolation. the lowliest monk	[reply] [d/l]
Re: CGI script query by cool_jr256 (Acolyte) on Jun 08, 2005 at 13:48 UTC
Here is your mistake: instaed of `print $query->("dssp file used is $dssp_file");` [download] do this `print $query->body("dssp file used is $dssp_file");` [download] Oh and btw use "" not ''	[reply] [d/l] [select]
Re: CGI script query by monarch (Priest) on Jun 08, 2005 at 13:43 UTC
During development it helps to add the following line to your CGI script: `use CGI::Carp qw( fatalsToBrowser );` [download] This will, hopefully, cause an error to be sent to your web browser if something went wrong with your script. Next, the line in your code: `print $query->('dssp file used is $dssp_file');` [download] makes me wonder if you didn't mean something like this: `print $query->p('dssp file used is $dssp_file');` [download] .. at least `->p()` is a function implemented in CGI (it wraps `<p>...</p>` tags around your text).. I don't know what the behaviour of the `->()` call would be from your CGI object `$query`. Finally, as holli mentions, you appear to be missing lines of code, not least because I couldn't count 45 lines there to find your error.. or at least look at the 2 or 3 preceeding lines that may have caused the error. PS: did you add `use strict;` to your script.. Considered (holli): force insert "Update notification". author changed original content and did not react to a /msg Unconsidered (holli): Enough keep votes (Keep/Edit/Delete: 6/12/0)	[reply] [d/l] [select]
Re^2: CGI script query by tlm (Prior) on Jun 08, 2005 at 13:53 UTC
To the OP, note well that monarch wrote "during development." I.e., disable `fatalsToBrowser` in your production code, because it is a "huge security hole". the lowliest monk	[reply]
Re^3: CGI script query by Angharad (Pilgrim) on Jun 08, 2005 at 14:52 UTC
Oh right, thanks very much. I appreciate everyones help. Got it sorted now.	[reply]