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
Changes in 4.4
The default headers now include 'Accept-Encoding' => 'identity' to minimize trouble with servers that respond with malformed compressed responses, as explained here.
Changes in 4.3
- The Document API has been extended with one new method
page.best_titlethat returns the longest text available from a selection of candidates. to_hashnow includesscheme,host,root_url,best_titleanddescription.
Changes in 4.2
The images API has been extended, with two new methods:
page.images.owner_suggestedreturns the OG or Twitter image, ornilif neither are present.page.images.largestreturns the largest image found in the page. This uses the HTML height and width attributes as well as the fastimage gem to return the largest image on the page that has a ratio squarer than 1:10 or 10:1. This usually provides a good alternative to the OG or Twitter images if they are not supplied.
The criteria for
page.images.besthas changed slightly, we'll now return the largest image instead of the first image if no owner-suggested image is found.
Changes in 4.1
- Introduces the
:normalize_urloption, which allows to disable URL normalization.
Changes in 4.0
- The links API has been changed, now instead of
page.links,page.internal_linksandpage.external_linkswe have:
page.links.raw # Returns all links found, unprocessed
page.links.all # Returns all links found, unrelavitized and absolutified
page.links.http # Returns all HTTP links found
page.links.non_http # Returns all non-HTTP links found
page.links.internal # Returns all internal HTTP links found
page.links.external # Returns all external HTTP links found
The images API has been changed, now instead of
page.imagewe havepage.images.best, and instead ofpage.faviconwe havepage.images.favicon.Now
page.imagewill return the first image inpage.imagesif no OG or Twitter image found, instead of returningnil.You can now specify 2 different timeouts,
connection_timeoutandread_timeout, instead of the previous singletimeout.
Changes in 3.0
- The redirect API has been changed, now the
:allow_redirectionsoption will expect only a boolean, which by default istrue. That is, no more specifying:safe,:unsafeor:all. - We've dropped support for Ruby < 2.
Also, we've introduced a new feature:
- Persist cookies across redirects. Now MetaInspector will include the received cookies when following redirects. This fixes some cases where a redirect would fail, sometimes caught in a redirection loop.
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 2.0.0 and 2.1.3.
Usage
Initialize a MetaInspector instance for an URL, like this:
page = MetaInspector.new('http://sitevalidator.com')
If you don't include the scheme on the URL, http:// will be used by default:
page = MetaInspector.new('sitevalidator.com')
You can also include the html which will be used as the document to scrape:
page = MetaInspector.new("http://sitevalidator.com", :document => "<html><head><title>Hello From Passed Html</title><a href='/hello'>Hello link</a></head><body></body></html>")
Accessing response status and headers
You can check the status and headers from the response like this:
page.response.status # 200
page.response.headers # { "server"=>"nginx", "content-type"=>"text/html; charset=utf-8", "cache-control"=>"must-revalidate, private, max-age=0", ... }
Accessing scraped data
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, sitevalidator.com, without the scheme)
page.root_url # Root url (scheme + host, like http://sitevalidator.com/)
page.title # title of the page from the head section, as string
page.best_title # best title of the page, from a selection of candidates
page.links.raw # every link found, unprocessed
page.links.all # every link found on the page as an absolute URL
page.links.http # every HTTP link found
page.links.non_http # every non-HTTP link found
page.links.internal # every internal link found on the page as an absolute URL
page.links.external # every external link found on the page as an absolute URL
page.['keywords'] # meta keywords, as string
page.['description'] # meta description, as string
page.description # returns the meta description, or the first long paragraph if no meta description is found
page.images # enumerable collection, with every img found on the page as an absolute URL
page.images.best # Most relevant image, if defined with the og:image or twitter:image metatags. Fallback to the first page.images array element
page.images.favicon # absolute URL to the favicon
page.feed # Get rss or atom links in meta data fields as array
page.charset # UTF-8
page.content_type # content-type returned by the server when the url was requested
Meta tags
When it comes to meta tags, you have several options:
page.meta_tags # Gives you all the meta tags by type:
# (meta name, meta http-equiv, meta property and meta charset)
# As meta tags can be repeated (in the case of 'og:image', for example),
# the values returned will be arrays
#
# For example:
#
# {
'name' => {
'keywords' => ['one, two, three'],
'description' => ['the description'],
'author' => ['Joe Sample'],
'robots' => ['index,follow'],
'revisit' => ['15 days'],
'dc.date.issued' => ['2011-09-15']
},
'http-equiv' => {
'content-type' => ['text/html; charset=UTF-8'],
'content-style-type' => ['text/css']
},
'property' => {
'og:title' => ['An OG title'],
'og:type' => ['website'],
'og:url' => ['http://example.com/meta-tags'],
'og:image' => ['http://example.com/rock.jpg',
'http://example.com/rock2.jpg',
'http://example.com/rock3.jpg'],
'og:image:width' => ['300'],
'og:image:height' => ['300', '1000']
},
'charset' => ['UTF-8']
}
As this method returns a hash, you can also take only the key that you need, like in:
page.['property'] # Returns:
# {
# 'og:title' => ['An OG title'],
# 'og:type' => ['website'],
# 'og:url' => ['http://example.com/meta-tags'],
# 'og:image' => ['http://example.com/rock.jpg',
# 'http://example.com/rock2.jpg',
# 'http://example.com/rock3.jpg'],
# 'og:image:width' => ['300'],
# 'og:image:height' => ['300', '1000']
# }
In most cases you will only be interested in the first occurrence of a meta tag, so you can use the singular form of that method:
page.['name'] # Returns:
# {
# 'keywords' => 'one, two, three',
# 'description' => 'the description',
# 'author' => 'Joe Sample',
# 'robots' => 'index,follow',
# 'revisit' => '15 days',
# 'dc.date.issued' => '2011-09-15'
# }
Or, as this is also a hash:
page.['name']['keywords'] # Returns 'one, two, three'
And finally, you can use the shorter meta method that will merge the different keys so you have
a simpler hash:
page. # Returns:
#
# {
# 'keywords' => 'one, two, three',
# 'description' => 'the description',
# 'author' => 'Joe Sample',
# 'robots' => 'index,follow',
# 'revisit' => '15 days',
# 'dc.date.issued' => '2011-09-15',
# 'content-type' => 'text/html; charset=UTF-8',
# 'content-style-type' => 'text/css',
# 'og:title' => 'An OG title',
# 'og:type' => 'website',
# 'og:url' => 'http://example.com/meta-tags',
# 'og:image' => 'http://example.com/rock.jpg',
# 'og:image:width' => '300',
# 'og:image:height' => '300',
# 'charset' => 'UTF-8'
# }
This way, you can get most meta tags just like that:
page.['author'] # Returns "Joe Sample"
Please be aware that all keys are converted to downcase, so it's 'dc.date.issued' and not 'DC.date.issued'.
Other representations
You can also access most of the scraped data as a hash:
page.to_hash # { "url" => "http://sitevalidator.com",
"title" => "MarkupValidator :: site-wide markup validation tool", ... }
The original document is accessible from:
page.to_s # A String with the contents of the HTML document
And the full scraped document is accessible from:
page.parsed # Nokogiri doc that you can use it to get any element from the page
Options
Timeout & Retries
You can specify 2 different timeouts when requesting a page:
connection_timeoutsets the maximum number of seconds to wait to get a connection to the page.read_timeoutsets the maximum number of seconds to wait to read the page, once connected.
Both timeouts default to 20 seconds each.
You can also specify the number of retries, which defaults to 3.
For example, this will time out after 10 seconds waiting for a connection, or after 5 seconds waiting to read its contents, and will retry 4 times:
page = MetaInspector.new('www.google', :connection_timeout => 10, :read_timeout => 5, :retries => 4)
If MetaInspector fails to fetch the page after it has exhausted its retries,
it will raise Faraday::TimeoutError, which you can rescue in your
application code.
begin
page = MetaInspector.new(url)
rescue Faraday::TimeoutError
enqueue_for_future_fetch_attempt(url)
render_simple(url)
else
render_rich(page)
end
Redirections
By default, MetaInspector will follow redirects (up to a limit of 10).
If you want to disallow redirects, you can do it like this:
page = MetaInspector.new('facebook.com', :allow_redirections => false)
Headers
By default, the following headers are set:
{
'User-Agent' => "MetaInspector/#{MetaInspector::VERSION} (+https://github.com/jaimeiniesta/metainspector)",
'Accept-Encoding' => 'identity'
}
The Accept-Encoding is set to identity to avoid exceptions being raised on servers that return malformed compressed responses, as explained here.
If you want to override the default headers then use the headers option:
# Set the User-Agent header
page = MetaInspector.new('example.com', :headers => {'User-Agent' => 'My custom User-Agent'})
HTML Content Only
MetaInspector will try to parse all URLs by default. If you want to raise an exception 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('sitevalidator.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.content_type # "image/png"
page.description # will returned a garbled string
page = MetaInspector.new('http://example.com/image.png', :html_content_only => true)
page.content_type # "image/png"
page.description # raises an exception
URL Normalization
By default, URLs are normalized using the Addressable gem. For example:
# Normalization will add a default scheme and a trailing slash...
page = MetaInspector.new('sitevalidator.com')
page.url # http://sitevalidator.com/
# ...and it will also convert international characters
page = MetaInspector.new('http://www.詹姆斯.com')
page.url # http://www.xn--8ws00zhy3a.com/
While this is generally useful, it can be tricky sometimes.
You can disable URL normalization by passing the normalize_url: false option.
Image downloading
When you ask for the largest image on the page with page.images.largest, it will be determined by its height and width attributes on the HTML markup, and also by downloading a small portion of each image using the fastimage gem. This is really fast as it doesn't download the entire images, normally just the headers of the image files.
If you want to disable this, you can specify it like this:
page = MetaInspector.new('http://example.com', download_images: false)
Exception Handling
By default, MetaInspector will raise the exceptions found. We think that this is the safest default: in case the URL you're trying to scrape is unreachable, you should clearly be notified, and treat the exception as needed in your app.
However, if you prefer you can also set the warn_level: :warn option, so that exceptions found will just be warned on the standard output, instead of being raised.
You can also set the warn_level: :store option so that exceptions found will be silenced, and left for you to inspect on page.exceptions. You can also ask for page.ok?, wich will return true if no exceptions are stored.
You should avoid using the :store option, or use it wisely, as silencing errors can be problematic, it's always better to face the errors and treat them accordingly.
Examples
You can find some sample scripts on the examples 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://sitevalidator.com')
=> #<MetaInspector:0x11330c0 @url="http://sitevalidator.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"
Contributing guidelines
You're more than welcome to fork this project and send pull requests. Just remember to:
- Create a topic branch for your changes.
- Add specs.
- Keep your fake responses as small as possible. For each change in
spec/fixtures, a comment should be included explaining why it's needed. - Update
version.rb, following the semantic versioning convention. - Update
README.mdif needed (for example, when you're adding or changing a feature).
Thanks to all the contributors:
https://github.com/jaimeiniesta/metainspector/graphs/contributors
You can also come to chat with us on our Gitter room and Google group.
Related projects
- go-metainspector, a port of MetaInspector for Go.
- Node-MetaInspector, a port of MetaInspector for Node.
License
MetaInspector is released under the MIT license.