Tatsuhiko Miyagawa > Web-Scraper > Web::Scraper

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NAME ^

Web::Scraper - Web Scraping Toolkit using HTML and CSS Selectors or XPath expressions

SYNOPSIS ^

  use URI;
  use Web::Scraper;
  use Encode;

  # First, create your scraper block
  my $authors = scraper {
      # Parse all TDs inside 'table[width="100%]"', store them into
      # an array 'authors'.  We embed other scrapers for each TD.
      process 'table[width="100%"] td', "authors[]" => scraper {
        # And, in each TD,
        # get the URI of "a" element
        process "a", uri => '@href';
        # get text inside "small" element
        process "small", fullname => 'TEXT';
      };
  };

  my $res = $authors->scrape( URI->new("http://search.cpan.org/author/?A") );

  # iterate the array 'authors'
  for my $author (@{$res->{authors}}) {
      # output is like:
      # Andy Adler      http://search.cpan.org/~aadler/
      # Aaron K Dancygier       http://search.cpan.org/~aakd/
      # Aamer Akhter    http://search.cpan.org/~aakhter/
      print Encode::encode("utf8", "$author->{fullname}\t$author->{uri}\n");
  }

The structure would resemble this (visually) { authors => [ { fullname => $fullname, link => $uri }, { fullname => $fullname, link => $uri }, ] }

DESCRIPTION ^

Web::Scraper is a web scraper toolkit, inspired by Ruby's equivalent Scrapi. It provides a DSL-ish interface for traversing HTML documents and returning a neatly arranged Perl data structure.

The scraper and process blocks provide a method to define what segments of a document to extract. It understands HTML and CSS Selectors as well as XPath expressions.

METHODS ^

scraper

  $scraper = scraper { ... };

Creates a new Web::Scraper object by wrapping the DSL code that will be fired when scrape method is called.

scrape

  $res = $scraper->scrape(URI->new($uri));
  $res = $scraper->scrape($html_content);
  $res = $scraper->scrape(\$html_content);
  $res = $scraper->scrape($http_response);
  $res = $scraper->scrape($html_element);

Retrieves the HTML from URI, HTTP::Response, HTML::Tree or text strings and creates a DOM object, then fires the callback scraper code to retrieve the data structure.

If you pass URI or HTTP::Response object, Web::Scraper will automatically guesses the encoding of the content by looking at Content-Type headers and META tags. Otherwise you need to decode the HTML to Unicode before passing it to scrape method.

You can optionally pass the base URL when you pass the HTML content as a string instead of URI or HTTP::Response.

  $res = $scraper->scrape($html_content, "http://example.com/foo");

This way Web::Scraper can resolve the relative links found in the document.

process

  scraper {
      process "tag.class", key => 'TEXT';
      process '//tag[contains(@foo, "bar")]', key2 => '@attr';
      process '//comment()', 'comments[]' => 'TEXT';
  };

process is the method to find matching elements from HTML with CSS selector or XPath expression, then extract text or attributes into the result stash.

If the first argument begins with "//" or "id(" it's treated as an XPath expression and otherwise CSS selector.

  # <span class="date">2008/12/21</span>
  # date => "2008/12/21"
  process ".date", date => 'TEXT';

  # <div class="body"><a href="http://example.com/">foo</a></div>
  # link => URI->new("http://example.com/")
  process ".body > a", link => '@href';

  # <div class="body"><!-- HTML Comment here --><a href="http://example.com/">foo</a></div>
  # comment => " HTML Comment here "
  #
  # NOTES: A comment nodes are accessed when installed
  # the HTML::TreeBuilder::XPath (version >= 0.14) and/or
  # the HTML::TreeBuilder::LibXML (version >= 0.13)
  process "//div[contains(@class, 'body')]/comment()", comment => 'TEXT';

  # <div class="body"><a href="http://example.com/">foo</a></div>
  # link => URI->new("http://example.com/"), text => "foo"
  process ".body > a", link => '@href', text => 'TEXT';

  # <ul><li>foo</li><li>bar</li></ul>
  # list => [ "foo", "bar" ]
  process "li", "list[]" => "TEXT";

  # <ul><li id="1">foo</li><li id="2">bar</li></ul>
  # list => [ { id => "1", text => "foo" }, { id => "2", text => "bar" } ];
  process "li", "list[]" => { id => '@id', text => "TEXT" };

process_first

process_first is the same as process but stops when the first matching result is found.

  # <span class="date">2008/12/21</span>
  # <span class="date">2008/12/22</span>
  # date => "2008/12/21"
  process_first ".date", date => 'TEXT';

result

result allows to return not the default value after processing but a single value specified by a key or a hash reference built from several keys.

  process 'a', 'want[]' => 'TEXT';
  result 'want';

EXAMPLES ^

There are many examples in the eg/ dir packaged in this distribution. It is recommended to look through these.

NESTED SCRAPERS ^

Scrapers can be nested thus allowing to scrape already captured data.

  # <ul>
  # <li class="foo"><a href="foo1">bar1</a></li>
  # <li class="bar"><a href="foo2">bar2</a></li>
  # <li class="foo"><a href="foo3">bar3</a></li>
  # </ul>
  # friends => [ {href => 'foo1'}, {href => 'foo2'} ];
  process 'li', 'friends[]' => scraper {
    process 'a', href => '@href',
  };

FILTERS ^

Filters are applied to the result after processing. They can be declared as anonymous subroutines or as class names.

  process $exp, $key => [ 'TEXT', sub { s/foo/bar/ } ];
  process $exp, $key => [ 'TEXT', 'Something' ];
  process $exp, $key => [ 'TEXT', '+MyApp::Filter::Foo' ];

Filters can be stacked

  process $exp, $key => [ '@href', 'Foo', '+MyApp::Filter::Bar', \&baz ];

More about filters you can find in Web::Scraper::Filter documentation.

XML backends ^

By default HTML::TreeBuilder::XPath is used, this can be replaces by a XML::LibXML backend using Web::Scraper::LibXML module.

  use Web::Scraper::LibXML;

  # same as Web::Scraper
  my $scraper = scraper { ... };

AUTHOR ^

Tatsuhiko Miyagawa <miyagawa@bulknews.net>

LICENSE ^

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO ^

http://blog.labnotes.org/category/scrapi/

HTML::TreeBuilder::XPath

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