Web::Scraper

Practical Web Scraping with Web::Scraper Tatsuhiko Miyagawa [email_address] Six Apart, Ltd. / Shibuya Perl Mongers YAPC::Europe 2007 Vienna

Tatsuhiko Miyagawa

CPAN: MIYAGAWA

abbreviation Acme::Module::Authors Acme::Sneeze Acme::Sneeze::JP Apache::ACEProxy Apache::AntiSpam Apache::Clickable Apache::CustomKeywords Apache::DefaultCharset Apache::GuessCharset Apache::JavaScript::DocumentWrite Apache::No404Proxy Apache::Profiler Apache::Session::CacheAny Apache::Session::Generate::ModUniqueId Apache::Session::Generate::ModUsertrack Apache::Session::PHP Apache::Session::Serialize::YAML Apache::Singleton Apache::StickyQuery Archive::Any::Create Attribute::Profiled Attribute::Protected Attribute::Unimplemented Bundle::Sledge capitalization Catalyst::Plugin::JSONRPC Catalyst::View::Jemplate Catalyst::View::JSON CGI::Untaint::email Class::DBI::AbstractSearch Class::DBI::Extension Class::DBI::Pager Class::DBI::Replication Class::DBI::SQLite Class::DBI::View Class::Trigger Convert::Base32 Convert::DUDE Convert::RACE Date::Japanese::Era Date::Range::Birth Device::KeyStroke::Mobile Dunce::time Email::Find Email::Valid::Loose Encode::JavaScript::UCS Encode::JP::Mobile Encode::Punycode File::Find::Rule::Digest Geo::Coder::Google HTML::Entities::ImodePictogram HTML::RelExtor HTML::ResolveLink HTML::XSSLint HTTP::MobileAgent HTTP::ProxyPAC HTTP::Server::Simple::Authen IDNA::Punycode Inline::Basic Inline::TT JSON::Syck Kwiki::Emoticon Kwiki::Export Kwiki::Footnote Kwiki::OpenSearch Kwiki::OpenSearch::Service Kwiki::TypeKey Kwiki::URLBL Log::Dispatch::Config Log::Dispatch::DBI Mac::Macbinary Mail::Address::MobileJp Mail::ListDetector::Detector::Fml MSIE::MenuExt Net::DAAP::Server::AAC Net::IDN::Nameprep Net::IPAddr::Find Net::YahooMessenger NetAddr::IP::Find PHP::Session plagger Plagger POE::Component::Client::AirTunes POE::Component::YahooMessenger Template::Plugin::Clickable Template::Plugin::Comma Template::Plugin::FillInForm Template::Plugin::HTML::Template Template::Plugin::JavaScript Template::Plugin::MobileAgent Template::Plugin::Shuffle Template::Provider::Encoding Term::Encoding Term::TtyRec Text::Emoticon Text::Emoticon::GoogleTalk Text::Emoticon::MSN Text::Emoticon::Yahoo Text::MessageFormat Time::Duration::ja Time::Duration::Parse Web::Scrape WebService::Bloglines WebService::ChangesXml WebService::Google::Suggest WWW::Baseball::NPB WWW::Blog::Metadata::MobileLinkDiscovery WWW::Blog::Metadata::OpenID WWW::Blog::Metadata::OpenSearch WWW::Cache::Google WWW::OpenSearch XML::Atom XML::Atom::Lifeblog XML::Atom::Stream XML::Liberal

http://code.sixapart.com/

Practical Web Scraping
with Web::Scraper

Web pages are built using text-based mark-up languages ( HTML and XHTML ), and frequently contain a wealth of useful data in text form. However, most web pages are designed for human consumption, and frequently mix content with presentation. Thus, screen scrapers were reborn in the web era to extract machine-friendly data from HTML and other markup. http://en.wikipedia.org/wiki/Screen_scraping

"Screen-scraping
is so 1999!"

RSS is a metadata
not a complete
HTML replacement

with Web::Scraper

What's wrong with
LWP & Regexp?

<td>Current UTC (or GMT/Zulu)-time used: Monday, August 27, 2007 at 12:49:46

<td>Current UTC (or GMT/Zulu)-time used: Monday, August 27, 2007 at 12:49:46 > perl -MLWP::Simple -le '$c = get("http://timeanddate.com/worldclock/"); $c =~ m@(.*?)@ and print $1' Monday, August 27, 2007 at 12:49:46

It works!

WWW::MySpace 0.70

WWW::Search::Ebay 2.231

WWW::Mixi 0.50

It works …

There are
3 problems
(at least)

(1)
Fragile
Easy to break even with slight HTML changes
(like newlines, order of attributes etc.)

(2)
Hard to maintain
Regular expression based scrapers are good
Only when they're used in write-only scripts

(3)
Improper
HTML & encoding
handling

I &hearts; Vienna > perl –e '$c =~ m@(.*?)@ and print $1' I &hearts; Vienna

I &hearts; Vienna > perl –MHTML::Entities –e '$c =~ m@(.*?)@ and print decode_entities ($1)' I ♥ Vienna

ウィーンが大好き！ > perl –MHTML::Entities –MEncode –e '$c =~ m@(.*?)@ and print decode_entities( decode_utf8 ($1))' Wide character in print at –e line 1. ウィーンが大好き！

The "right" way
of screen-scraping

(1), (2)
Maintainable
Less fragile

Use XPath
and CSS Selectors

XPath
HTML::TreeBuilder::XPath
XML::LibXML

XPath <td>Current UTC (or GMT/Zulu)-time used: Monday, August 27, 2007 at 12:49:46 use HTML::TreeBuilder::XPath; my $tree = HTML::TreeBuilder::XPath->new_from_content($content); print $tree->findnodes ('//strong[@id="ctu"]') ->shift->as_text; # Monday, August 27, 2007 at 12:49:46

CSS Selectors
"XPath for HTML coders"
"XPath for people who hates XML"

CSS Selectors
body { font-size: 12px; }
div.article { padding: 1em }
span#count { color: #fff }

XPath:
//strong[@id="ctu"]
CSS Selector:
strong#ctu

CSS Selectors <td>Current UTC (or GMT/Zulu)-time used: Monday, August 27, 2007 at 12:49:46 use HTML::TreeBuilder::XPath; use HTML::Selector::XPath qw(selector_to_xpath); my $tree = HTML::TreeBuilder::XPath->new_from_content($content); my $xpath = selector_to_xpath "strong#ctu"; print $tree->findnodes($xpath)->shift->as_text; # Monday, August 27, 2007 at 12:49:46

Complete Script #!/usr/bin/perl use strict; use warnings; use Encode; use LWP::UserAgent; use HTTP::Response::Encoding; use HTML::TreeBuilder::XPath; use HTML::Selector::XPath qw(selector_to_xpath); my $ua = LWP::UserAgent->new; my $res = $ua->get("http://www.timeanddate.com/worldclock/"); if ($res->is_error) { die "HTTP GET error: ", $res->status_line; } my $content = decode $res->encoding, $res->content; my $tree = HTML::TreeBuilder::XPath->new_from_content($content); my $xpath = selector_to_xpath("strong#ctu"); my $node = $tree->findnodes($xpath)->shift; print $node->as_text;

Robust,
Maintainable,
and
Sane character handling

Exmaple (before) <td>Current UTC (or GMT/Zulu)-time used: Monday, August 27, 2007 at 12:49:46 > perl -MLWP::Simple -le '$c = get("http://timeanddate.com/worldclock/"); $c =~ m@(.*?)@ and print $1' Monday, August 27, 2007 at 12:49:46

Example (after) #!/usr/bin/perl use strict; use warnings; use Encode; use LWP::UserAgent; use HTTP::Response::Encoding; use HTML::TreeBuilder::XPath; use HTML::Selector::XPath qw(selector_to_xpath); my $ua = LWP::UserAgent->new; my $res = $ua->get("http://www.timeanddate.com/worldclock/"); if ($res->is_error) { die "HTTP GET error: ", $res->status_line; } my $content = decode $res->encoding, $res->content; my $tree = HTML::TreeBuilder::XPath->new_from_content($content); my $xpath = selector_to_xpath("strong#ctu"); my $node = $tree->findnodes($xpath)->shift; print $node->as_text;

but …
long and boring

with Web::Scraper

Web scraping toolkit
inspired by scrapi.rb
DSL-ish

Example (before) #!/usr/bin/perl use strict; use warnings; use Encode; use LWP::UserAgent; use HTTP::Response::Encoding; use HTML::TreeBuilder::XPath; use HTML::Selector::XPath qw(selector_to_xpath); my $ua = LWP::UserAgent->new; my $res = $ua->get("http://www.timeanddate.com/worldclock/"); if ($res->is_error) { die "HTTP GET error: ", $res->status_line; } my $content = decode $res->encoding, $res->content; my $tree = HTML::TreeBuilder::XPath->new_from_content($content); my $xpath = selector_to_xpath("strong#ctu"); my $node = $tree->findnodes($xpath)->shift; print $node->as_text;

Example (after)
#!/usr/bin/perl
use strict;
use warnings;
use Web::Scraper;
use URI;
my $s = scraper {
process "strong#ctu", time => 'TEXT';
result 'time';
};
my $uri = URI->new("http://timeanddate.com/worldclock/");
print $s->scrape($uri);

Basics
use Web::Scraper;
my $s = scraper {
# DSL goes here
};
my $res = $s->scrape($uri);

process
process $selector,
$key => $what,
… ;

$selector:
CSS Selector
or
XPath (start with /)

$key:
key for the result hash
append "[]" for looping

$what:
'@attr'
'TEXT'
Web::Scraper
sub { … }
Hash reference

<ul class="sites"> <li><a href="http://vienna.openguides.org/">OpenGuides</a></li> <li><a href="http://vienna.yapceurope.org/">YAPC::Europe</a></li> </ul>

process "ul.sites > li > a",
'urls[]' => ' @href ';
# { urls => [ … ] }
<ul class="sites"> <li><a href=" http://vienna.openguides.org/ ">OpenGuides</a></li> <li><a href=" http://vienna.yapceurope.org/ ">YAPC::Europe</a></li> </ul>

process '//ul[@class="sites"]/li/a',
'names[]' => ' TEXT ';
# { names => [ 'OpenGuides', … ] }
<ul class="sites"> <li><a href="http://vienna.openguides.org/"> OpenGuides </a></li> <li><a href="http://vienna.yapceurope.org/"> YAPC::Europe </a></li> </ul>

process "ul.sites > li",
'sites[]' => scraper {
process 'a',
link => '@href', name => 'TEXT';
};
# { sites => [ { link => …, name => … },
# { link => …, name => … } ] };

'sites[]' => sub {
# $_ is HTML::Element
+{ link => $_->attr('href'), name => $_->as_text };
};
# { sites => [ { link => …, name => … },
# { link => …, name => … } ] };

'sites[]' => {
link => '@href', name => 'TEXT';
};
# { sites => [ { link => …, name => … },
# { link => …, name => … } ] };

result
result;
# get stash as hashref (default)
result @keys;
# get stash as hashref containing @keys
result $key;
# get value of stash $key;
my $s = scraper { process …; process …; result 'foo', 'bar'; };

More Examples

Thumbnail URLs on Flickr set
#!/usr/bin/perl
use strict;
use Data::Dumper;
use Web::Scraper;
use URI;
my $url = "http://flickr.com/photos/bulknews/sets/72157601700510359/";
my $s = scraper {
process "a.image_link img", "thumbs[]" => '@src';
};
warn Dumper $s->scrape( URI->new($url) );

<a href="http://twitter.com/iamcal" class="url" rel="contact" title="Cal Henderson"> <img alt="Cal Henderson" class="photo fn" height="24" id="profile-image" src="http://assets0.twitter.com/…/mini/buddyicon.gif" width="24" /></a> …

Twitter Friends
#!/usr/bin/perl
use strict;
use Web::Scraper;
use URI;
use Data::Dumper;
my $url = "http://twitter.com/miyagawa";
my $s = scraper {
process "span.vcard a", "people[]" => '@title';
};
warn Dumper $s->scrape( URI->new($url) ) ;

Twitter Friends (complex)
#!/usr/bin/perl
use strict;
use Web::Scraper;
use URI;
use Data::Dumper;
my $url = "http://twitter.com/miyagawa";
my $s = scraper {
process "span.vcard", "people[]" => scraper {
process "a", link => '@href', name => '@title';
process "img", thumb => '@src';
};
};
warn Dumper $s->scrape( URI->new($url) ) ;

> cpan Web::Scraper
comes with 'scraper' CLI

> scraper http://example.com/
scraper> process "a", "links[]" => '@href';
scraper> d
$VAR1 = {
links => [
'http://example.org/',
'http://example.net/',
],
};
scraper> y
---
links:
- http://example.org/
- http://example.net/

> scraper /path/to/foo.html
> GET http://example.com/ | scraper

Web::Scraper
Needs documentation

More examples
to put in eg/ directory

integrate with
WWW::Mechanize
and Test::WWW::Declare

XPath Auto-suggestion
off of DOM + element
DOM + XPath => Element
DOM + Element => XPath?
(Template::Extract?)

Questions?

Thank you
http://search.cpan.org/dist/Web-Scraper
http://www.slideshare.net/miyagawa/webscraper

http://blog.bulknews.net	952
http://coderwall.com	249
http://perlbuzz.com	79
http://teusje.wordpress.com	45
http://www.slideshare.net	24
http://thomas-fahle.blogspot.com	19
http://www.perlbuzz.com	5
http://kevinspencer.org	4
http://perl-howto.de	4
http://s3.amazonaws.com	3
http://intranet.sixapart.jp	2
http://www.filescon.com	2
http://66.102.9.104	2
http://feeds.feedburner.com	1
http://static.slideshare.net	1
http://www.rapidor.com	1
http://72.14.253.104	1
http://babelfish.altavista.com	1
http://feedpath.jp	1
http://lj-toys.com	1
http://localhost:3000	1

Web::Scraper

by Tatsuhiko Miyagawa on Aug 29, 2007

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Web::Scraper — Presentation Transcript