MetaInspector

MetaInspector is a gem for web scraping purposes. You give it an URL, and it lets you easily get its title, links, images, charset, description, keywords, meta tags...

See it in action!

You can try MetaInspector live at this little demo: https://metainspectordemo.herokuapp.com

Installation

Install the gem from RubyGems:

gem install metainspector

If you're using it on a Rails application, just add it to your Gemfile and run bundle install

gem 'metainspector'

This gem is tested on Ruby versions 1.8.7, 1.9.2 and 1.9.3.

Usage

Initialize a MetaInspector instance for an URL, like this:

page = MetaInspector.new('http://markupvalidator.com')

If you don't include the scheme on the URL, http:// will be used by default:

page = MetaInspector.new('markupvalidator.com')

You can also include the html which will be used as the document to scrape:

page = MetaInspector.new("http://markupvalidator.com", :document => "<html><head><title>Hello From Passed Html</title><a href='/hello'>Hello link</a></head><body></body></html>")

Accessing scraped data

Then you can see the scraped data like this:

page.url                # URL of the page
page.scheme             # Scheme of the page (http, https)
page.host               # Hostname of the page (like, markupvalidator.com, without the scheme)
page.root_url           # Root url (scheme + host, like http://markupvalidator.com/)
page.title              # title of the page, as string
page.links              # array of strings, with every link found on the page as an absolute URL
page.internal_links     # array of strings, with every internal link found on the page as an absolute URL
page.external_links     # array of strings, with every external link found on the page as an absolute URL
page.meta_description   # meta description, as string
page.description        # returns the meta description, or the first long paragraph if no meta description is found
page.meta_keywords      # meta keywords, as string
page.image              # Most relevant image, if defined with og:image
page.images             # array of strings, with every img found on the page as an absolute URL
page.feed               # Get rss or atom links in meta data fields as array
page.meta_og_title      # opengraph title
page.meta_og_image      # opengraph image
page.charset            # UTF-8
page.content_type       # content-type returned by the server when the url was requested

MetaInspector uses dynamic methods for meta_tag discovery, so all these will work, and will be converted to a search of a meta tag by the corresponding name, and return its content attribute

page.meta_description   # <meta name="description" content="..." />
page.meta_keywords      # <meta name="keywords" content="..." />
page.meta_robots        # <meta name="robots" content="..." />
page.meta_generator     # <meta name="generator" content="..." />

It will also work for the meta tags of the form , like the following:

page.meta_content_language  # <meta http-equiv="content-language" content="..." />
page.meta_Content_Type      # <meta http-equiv="Content-Type" content="..." />

Please notice that MetaInspector is case sensitive, so page.meta_Content_Type is not the same as page.meta_content_type

You can also access most of the scraped data as a hash:

page.to_hash  # { "url"   => "http://markupvalidator.com",
                  "title" => "MarkupValidator :: site-wide markup validation tool", ... }

The original document is accessible from:

page.document         # A String with the contents of the HTML document

And the full scraped document is accessible from:

page.parsed_document  # Nokogiri doc that you can use it to get any element from the page

Options

Timeout

By default, MetaInspector times out after 20 seconds of waiting for a page to respond. You can set a different timeout with a second parameter, like this:

page = MetaInspector.new('markupvalidator.com', :timeout => 5) # 5 seconds timeout

Redirections

By default, redirections from HTTP to HTTPS, and from HTTPS to HTTP are disallowed.

However, you can tell MetaInspector to allow these redirections with the option :allow_redirections, like this:

 # This will allow HTTP => HTTPS redirections
 page = MetaInspector.new('facebook.com', :allow_redirections => :safe)

 # And this will allow HTTP => HTTPS ("safe") and HTTPS => HTTP ("unsafe") redirections
 page = MetaInspector.new('facebook.com', :allow_redirections => :all)

HTML Content Only

MetaInspector will try to parse all URLs by default. If you want to raise an error when trying to parse a non-html URL (one that has a content-type different than text/html), you can state it like this:

page = MetaInspector.new('markupvalidator.com', :html_content_only => true)

This is useful when using MetaInspector on web spidering. Although on the initial URL you'll probably have an HTML URL, following links you may find yourself trying to parse non-html URLs.

page = MetaInspector.new('http://example.com/image.png')
page.title         # returns ""
page.content_type  # "image/png"
page.ok?           # true

page = MetaInspector.new('http://example.com/image.png', :html_content_only => true)
page.title         # returns nil
page.content_type  # "image/png"
page.ok?           # false 
page.errors.first  # "Scraping exception: The url provided contains image/png content instead of text/html content"

Error handling

You can check if the page has been succesfully parsed with:

page.ok?     # Will return true if everything looks OK

In case there have been any errors, you can check them with:

page.errors  # Will return an array with the error messages

If you also want to see the errors on console, you can initialize MetaInspector with the verbose option like that:

page = MetaInspector.new('http://example.com', :verbose => true)

Examples

You can find some sample scripts on the samples folder, including a basic scraping and a spider that will follow external links using a queue. What follows is an example of use from irb:

$ irb
>> require 'metainspector'
=> true

>> page = MetaInspector.new('http://markupvalidator.com')
=> #<MetaInspector:0x11330c0 @url="http://markupvalidator.com">

>> page.title
=> "MarkupValidator :: site-wide markup validation tool"

>> page.meta_description
=> "Site-wide markup validation tool. Validate the markup of your whole site with just one click."

>> page.meta_keywords
=> "html, markup, validation, validator, tool, w3c, development, standards, free"

>> page.links.size
=> 15

>> page.links[4]
=> "/plans-and-pricing"

>> page.document.class
=> String

>> page.parsed_document.class
=> Nokogiri::HTML::Document

ZOMG Fork! Thank you!

You're welcome to fork this project and send pull requests. Just remember to include specs.

Thanks to all the contributors:

https://github.com/jaimeiniesta/metainspector/graphs/contributors