PERL CGI Beginners - undefined value error

Author

undefined value error

Xiangli Zhang

2004-09-23, 8:55 pm

I got the following error when one cgi file 'test.cgi' was called from HTML:

Can't call method "sequence" on an undefined value

However I can run 'test.cgi' with command 'perl test.cgi' correctly.

Can anybody help me figure out the problem?

The following is my code: error happened on bold lines.

thanks,

#!/usr/bin/perl
use CGI;
use CGI::Carp qw(fatalsToBrowser);
use warnings;
use diagnostics;
use DNAalign;
use fastream;
use DNAseq;
print "Content-type: text/html\n\n";
print "<html><head><title>Perl CGI Example # 2";
print "</title></head><body><h1>";
print "Alignment Result </h1><p>";
print "<pre>";
chdir("/srv/www/httmp/default/chromat_dir");
my $seq1=fastream->new("default.fasta.screen.contigs");
my $seq2=fastream->new("secondFile");
my $test1=$seq1->next_seq();
my $test2=$seq2->next_seq();
my $s1=$test1->sequence();
my $s2=$test2->sequence();
print "input1===$s1\n";
print "input2===$s2\n";
($sa,$sb)=DNAalign::align($test1,$test1)
;
$result1=$sa->sequence();
$result2=$sb->sequence();
print "\n";
print "result1=== $result1\n";
print "result2=== $result2\n";
print "</pre>";
print "</p>";
print "</body></html>";

Xiangli Zhang (Justin)
306-310 Decaire Street, Coquitlam
BC, Canada, V3K 6X1
phone: 604-9399181

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Gunnar Hjalmarsson

2004-09-23, 8:55 pm

Xiangli Zhang wrote:
> I got the following error when one cgi file 'test.cgi' was called
> from HTML:
>
> Can't call method "sequence" on an undefined value
>
> However I can run 'test.cgi' with command 'perl test.cgi'
> correctly.
>
> Can anybody help me figure out the problem?

Well, you are not even letting us know from which line that error
message comes...

I don't know anything about those modules you are using, but I suppose
that their docs describe how to check for success. There is where I
would start the debugging work.

A mailing list should be the *last* resort.

--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl

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