cgi perl and iterating

h/w · 11-26-2007, 11:07 PM

Hi,

I have some list elements that I'd like to be iterated and turned into HTML elements, like an ordered list.

For example, given the following, is it possible to extend the same code to run over the list and print the list elements?

Code:

print ol(li(a({-href="foo"},"bar"))),"\n";

I've tried something like:

Code:

print "<ol>";foreach my $s (@some_list) {print "<li><a href="$s">$s</a></li>";
}
print "</ol>";

, but that doesn't do it.

Any ideas?
Thanks.

j-ray · 11-27-2007, 03:07 AM

your code contains " double qoutes that are not escaped within a string. Maybe this ws the problem?
if not
you may do the counting
my $counter=1;
foreach my $s (@some_list) {

print "<li><a href='$s'>$counter"."."." $s</a></li>";
$counter++;
}

bigearsbilly · 11-27-2007, 03:53 AM

Code:

use CGI qw/:standard/;
use CGI::Pretty;


@L = qw(one two three four);

@P = map {a({-href=>$_}, $_)} @L;     # make a list of anchors

print li(\@P);                        # pass  array ref to li

Code:

billym.primadtpdev>1.pl
<li>
        <a href="one">one</a>
</li>
<li>
        <a href="two">two</a>
</li>
<li>
        <a href="three">three</a>
</li>
<li>
        <a href="four">four</a>
</li>

owzthat

Code:

print ol( li(\@P));  # for the complete job

h/w · 11-27-2007, 09:55 AM

Thanks, you two.
They both would do, and I like the map usage.

My error is actually someplace before that block. I don't think I'm returning values correctly from a function. I'm executing a script using open(), which ends up writing it to STDOUT, and I don't seem to be getting those return values back in my caller.

Still got some way to go ...

Thanks, again.

chrism01 · 11-27-2007, 05:07 PM

Show us the code...
sounds like one of these may be useful: http://perldoc.perl.org/IPC/Open2.html , http://perldoc.perl.org/IPC/Open3.html

bigearsbilly · 11-28-2007, 02:13 AM

generic open reading...

Code:

open INPUT, "command |" or die;

while (INPUT) {
 
   # process $_ here
}

h/w · 11-28-2007, 10:08 AM

Thanks again, guys. I'll finally get some time today to understand more how things are to be done in Perl.
This is what I've been trying so far:

Code:

sub retTest {
  my $cmd = "|/absolute/path/to/the/command";
  my @results = ( );
  my @CMD = ( );

  open(CMD, "$cmd some_arg") or die("Can't fork command: $!\n");
  @results = @CMD;
  close CMD;

  return @results;
}

sub printTest {
  print "Make a selection:\n";
  my @results = &retTest();

  #using bigearsbilly's suggestion
  my @a = map {a({-href=>$_}, $_)} @results;
  print ol(li(\@a));
}

&printTest();

I certainly feel queasy with the line:

Code:

@results = @CMD;

, and am going to try your suggestions.

We shall see ...
Thanks, again.

h/w · 11-28-2007, 10:38 AM

Code:

sub retTest {
  my $cmd = "|/absolute/path/to/the/command";
  my @results = ( );
  my @CMD = ( );

  open(CMD, "$cmd some_arg") or die("Can't fork command: $!\n");
  while(<CMD>) {
    push(@results, $_);
  }
  close CMD;

  return @results;
}

Better, but the output of the command writes to STDOUT, and nothing is pushed onto @results.

h/w · 11-28-2007, 11:16 AM

Code:

sub retTest {
  my $cmd = "/absolute/path/to/the/command";
  my @results = `$cmd some_arg`;
  return @results;
}

, captures the output. So, the backticks suit my requirement.

But what if we want to make certain that it doesn't fail - there isn't a way to 'die' gracefully when using back-ticks, is there?
And, what would the open(),open2(),open3() equivalent be?

Thanks, again.

h/w · 11-28-2007, 11:59 AM

Quote:

Originally Posted by h/w

But what if we want to make certain that it doesn't fail - there isn't a way to 'die' gracefully when using back-ticks, is there?

Code:

sub retTest {
  my $cmd = "/absolute/path/to/the/command";
  my @results = `$cmd some_arg` or die("$!\n");
  return @results;
}

h/w · 11-28-2007, 11:00 PM

Ok, I've hit a bit of a snag.
If I run that script using 'perl -w script.cgi', I see the output of the command that was executed inside the script.
But if I hit up the webpage from a browser, it doesn't seem to be running the command (or if it is, it doesn't show up.)

Strange ...

bigearsbilly · 11-29-2007, 02:54 AM

for debugging only!

Code:

use diagnostics;
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);

check /var/log/apache/error_log (or similar)

j-ray · 11-29-2007, 02:55 AM

maybe a "permission denied" error as the cgi is run by the web user? ->error_log

h/w · 11-29-2007, 12:15 PM

Thanks again, guys.
My fault for posting without any details or without checking things out.

The issue had to do with relative paths being used in the external shell script, which I had to make absolute when running through httpd.