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

Hi Monks,

I'm a perl beginner and am learning to use the www::mechanize module to get a list of genome sequencing projects from http://www.ncbi.nlm.nih.gov/Traces/wgs/. After I fill in the form, I cannot figure out how to select 'All' from the 'Show projects on page' listbox.

I tried 'find_all_inputs' with 'select' as criteria for a listbox, but nothing gets assigned to the variable. My other issue is not being able to click on the 'Download as TAB delimited list' link to output results to file.

I can complete this task using the browser, but then I don't learn. Below are the few lines of code I have so far. Your advice will be a great help.

many thanks! 

#!/usr/local/bin/perl
use strict;
use warnings;
use autodie qw/ open close /;
use 5.012;
use WWW::Mechanize;

# create WWW::Mechanize object
# autocheck 1 checks each request to ensure it was successful
my $browser = WWW::Mechanize->new( autocheck => [1] );

# retrieve page
$browser->get( 'http://www.ncbi.nlm.nih.gov/Traces/wgs/' );

#select form to fill based on mech-dump output
$browser->form_number(1); 
# fill field 'term' with name of species
$browser->field( 'term', 'Escherichia' );

# click apply button
$browser->submit( 'Apply' );

my $url = $browser->uri;
# launch browser to test url
#system( 'firefox', $url );

my @inputs = $browser->find_all_inputs(
    type => 'select'
);
say @inputs;

[download]

Replies are listed 'Best First'.
Re: stuck with WWW::Mechanize drop down list
by spazm (Monk) on Jun 02, 2012 at 00:29 UTC
    The dropdown selector uses javascript to reload the page. It's dorky: 
    <select id="_size" name="size" onchange="var s=sURL + '&size=' + this.value; document.location.href=s"><option value="all">All</option><option value="50">50</option><option value="100">100</option></select>
    We can simulate this by adding an "&size=all" to the url. We'll do this by setting an extra field entry: 
    $browser->field( 'size', 'all' );

    [download]
    Example: 
    #!env perl
use strict;
use warnings;
use autodie qw/ open close /;
use 5.012;
use WWW::Mechanize;

# create WWW::Mechanize object
# autocheck 1 checks each request to ensure it was successful
my $browser = WWW::Mechanize->new( autocheck => [1] );

# retrieve page
$browser->get('http://www.ncbi.nlm.nih.gov/Traces/wgs/');

#select form to fill based on mech-dump output
$browser->form_number(1);

# fill field 'term' with name of species
$browser->field( 'term', 'Escherichia' );
$browser->field( 'size', 'all' );


# click apply button
$browser->submit('Apply');

my $url = $browser->uri;
print "url: $url\n";

# launch browser to test url
#system( 'firefox', $url );
print $browser->content();

    [download]
[reply]
[d/l]
[select]
      Now that you have the full list, you'd like to follow the link for the "Download as TAB delimited list". In your browser, following the link will lead to a saved file. In the mech, this will be just more content.

      If you want to be clever, you can get the filename from the LWP's HTTP::Response and use it as a filename to dump the file. 

      $browser->follow_link( text_regex => qr/Download as TAB/i );
print $browser->content();  # prints TAB delimited file to STDOUT

      [download]
      $browser->follow_link( text_regex => qr/Download as TAB/i );
if ( my $filename = $browser->res->filename )
{
    die "file already exists [$filename]" if -e $filename;
    print STDERR "Saving downloaded file to [$filename]\n";
    open my $fh, ">", $filename;
    print $fh $browser->content;
    close $fh;
}

      [download]
      #!env perl
use strict;
use warnings;
use autodie qw/ open close /;
use 5.012;
use WWW::Mechanize;

# create WWW::Mechanize object
# autocheck 1 checks each request to ensure it was successful
my $browser = WWW::Mechanize->new( autocheck => [1] );

# retrieve page
$browser->get('http://www.ncbi.nlm.nih.gov/Traces/wgs/');

#select form to fill based on mech-dump output
$browser->form_number(1);

# fill field 'term' with name of species
$browser->field( 'term', 'Escherichia' );
$browser->field( 'size', 'all' );


# click apply button
$browser->submit('Apply');

my $url = $browser->uri;
print "url: $url\n";

$browser->follow_link( text_regex => qr/Download as TAB/i );
#print $browser->content();  # prints TAB delimited file to STDOUT

if ( my $filename = $browser->res->filename )
{
    die "file already exists [$filename]" if -e $filename;
    print STDERR "Saving downloaded file to [$filename]\n";
    open my $fh, ">", $filename;
    print $fh $browser->content;
    close $fh;
}

      [download]
[reply]
[d/l]
[select]

        Spazm, thanks much, especially for the explanations!

        Question. If mech-dump doesn't output content of drop down lists, do I always need to look at the page source and, if so, then add the selection as a 'field' entry?

[reply]

Back to Seekers of Perl Wisdom