ive just started with ruby on rails the other day and i was wandering is it possible to using the puts function to get the content of a div from a page on an external page.
something like puts "http://www.example.com #about"
would something like this work ? or would you have to get the entire page and then puts that section that you wanted ?
additionaly if the content on the "example.com" #about div is constantly changing would puts constantly update its output or would it only run the script each time the page is refreshed ?
The open-uri library (for fetching the page) and the Nokogiri gem (for parsing and retrieving specific content) can assist with this.
require 'open-uri'
require 'nokogiri'
doc = Nokogiri::HTML(open('http://www.example.com/'))
puts doc.at('#about').text
puts will not work that way. Ruby makes parsing HTML fairly easy though. Take a look at the Nokogirl library, and you can use xpath queries to get to the div you want to print out. I believe you would need to reopen the file if the div changes, but I'm not positive about that - you can easily test it (or someone here can confirm or reject that statement).
Related
I can't get Nokogiri to return the same thing I see when I go to a page and "View Source". And for the life of me can't figure out why.
This is the page I am looking at:
http://www.amazon.com/gp/product/B009NWFP5Q
And as you can see it returns a shoe that's orange..and if I view the source and find the link I'm looking for by searching for "hiRes" twice, I get:
http://ecx.images-amazon.com/images/I/71b75uTtzDL.UL1500.jpg
However, if I run this code with Nokogiri:
require 'nokogiri'
require 'open-uri'
require 'uri'
url = "http://www.amazon.com/gp/product/B009NWFP5Q"
doc = Nokogiri::HTML(open(url))
pic = doc.css('div#imageBlock_feature_div script')[0]
puts pic
and look for the link in the same position I get this image:
http://ecx.images-amazon.com/images/I/81R97WG9nyL.UL1500.jpg
which is a BLUE shoe!!! Arghhh..
Any idea why??
Maybe the color being shown is somehow based on your session or dynamic attributes assigned to a cookie stored in your browser. Find a way to provide a URL that will return exactly what you are looking for. It may also be possible to provide a cookie using the http client code but that seems like a plan B.
I'm trying to get the bio of a Twitter profile using Nokogiri, and have tried everything to get an element using CSS. The follow returns an empty string:
doc = Nokogiri::HTML(open("https://twitter.com/n"))
puts doc.css('.ProfileHeaderCard-bio').text
However, if I try to output everything in the body, the content is indeed there. So the following works:
puts doc.css('body').text
But selecting by a CSS class fails: puts doc.css('.ProfileHeaderCard-bio').text
Any idea why?
Update:
Apparently Twitter changes CSS classes after load, so a browser's source code does something entirely different than what wget showed.
I am trying to get auto-corrected spelling from Google's home page using Nokogiri.
For example, if I am typing "hw did" and the correct spelling is "how did", I have to get the correct spelling.
I tried with the xpath and css methods, but in both cases, I get the same empty array.
I got the XPath and CSS paths using FireBug.
Here is my Nokogiri code:
#requ=params[:search]
#requ_url=#requ.gsub(" ","+") //to encode the url(if user inputs space than it should be convet into + )
#doc=Nokogiri::HTML(open("https://www.google.co.in/search?q=#{#requ_url}"))
binding.pry
Here are my XPath and CSS selectors:
Using XPath:
pry(#<SearchController>)> #doc.xpath("/html/body/div[5]/div[2]/div[6]/div/div[4]/div/div/div[2]/div/p/a").inspect
=> "[]"
Using CSS:
pry(#<SearchController>)> #doc.css('html body#gsr.srp div#main div#cnt.mdm div.mw div#rcnt div.col div#center_col div#taw div div.med p.ssp a.spell').inner_text()
=> ""
First, use the right tools to manipulate URLs; They'll save you headaches.
Here's how I'd find the right spelling:
require 'nokogiri'
require 'uri'
require 'open-uri'
requ = 'hw did'
uri = URI.parse('https://www.google.co.in/search')
uri.query = URI.encode_www_form({'q' => requ})
doc = Nokogiri::HTML(open(uri.to_s))
doc.at('a.spell').text # => "how did"
it works fine with "how did",check it with "bnglore" or any one word string,it gives an error. the same i was facing in my previous code. it is showing undefined method `text'
It's not that hard to figure out. They're changing the HTML so you have to change your selector. "Inspect" the suggested word "bangalore" and see where it exists in relation to the previous path. Once you know that, it's easy to find a way to access the word:
doc.at('span.spell').next_element.text # => "bangalore"
Don't trust Google to do things the easy way, or even the best way, or be consistent. Just because they return HTML one way for words with spaces, doesn't mean they're going to do it the same way for a single word. I would do it consistently, but they might be trying to discourage you from mining their pages so don't be surprised if you see variations.
Now, you need to figure out how to write code that knows when to use one selector/method or the other. That's for you to do.
I'm trying to scrape a web URL inputed by the user and then output an array of valid non-broken image elements with absolute paths in HTML. I'm using Nokogiri for scraping and I want to know if there is anything I can use to easily process the unpredicatble URLs provided by user and image paths scraped short of figuring out how to write something from scratch.
Examples:
http://domain.com/ and /system/images/image.png
=> http://domain.com/system/images/image.png
http://sub.domain.com and images/common/image.png
=> http://sub.domain.com/images/common/image.png
http://domain.com/dir/ and images/image.png
=> http://domain.com/dir/images/image.png
http://domain.com/dir and /images/small/image.png
=> http://domain.com/images/small/image.png
http://domain.com and http://s3.amazon-aws.com/bucket/image.png
=> http://s3.amazon-aws.com/bucket/image.png
Instead of downloading the pages and using Nokogiri, I would recommend using Mechanize. It is built on top of Nokogiri, so everything you can do with Nokogiri you can do with Mechanize, but it adds a lot of useful functionality for scraping/navigating. It will take care of the relative URL problem you describe above.
require 'rubygems'
require 'mechanize'
url='http://stackoverflow.com/questions/5903218/construct-urls-after-scraping-for-image-paths/5903417'
Mechanize.new.get(url) {|page| puts page.image_urls.join "\n"}
If you really want to do it yourself (instead of using Mechanize, say), use URI::join:
require 'uri'
URI::join("http://domain.com/dir", "/images/small/image.png")
# => http://domain.com/images/small/image.png
Note that you have to respect the HTML page's BASE tag if there is one...
Greetings everyone:
I would love to get some information from a huge collection of Google Search Result pages.
The only thing I need is the URLs inside a bunch of <cite></cite> HTML tags.
I cannot get a solution in any other proper way to handle this problem so now I am moving to ruby.
This is so far what I have written:
require 'net/http'
require 'uri'
url=URI.parse('http://www.google.com.au')
res= Net::HTTP.start(url.host, url.port){|http|
http.get('/#hl=en&q=helloworld')}
puts res.body
Unfortunately I cannot use the recommended hpricot ruby gem (because it misses a make command or something?)
So I would like to stick with this approach.
Now that I can get the response body as a string, the only thing I need is to retrieve whatever is inside the ciite(remove an i to see the true name :)) HTML tags.
How should I do that? using regular expression? Can anyone give me an example?
Here's one way to do it using Nokogiri:
Nokogiri::HTML(res.body).css("cite").map {|cite| cite.content}
I think this will solve it:
res.scan(/<cite>([^<>]*)<\/cite>/imu).flatten
# This one to ignore empty tags:
res.scan(/<cite>([^<>]*)<\/cite>/imu).flatten.select{|x| !x.empty?}
If you're having problems with hpricot, you could also try nokogiri which is very similar, and allows you to do the same things.
Split the string on the tag you want. Assuming only one instance of tag (or specify only one split) you'll have two pieces I'll call head and tail. Take tail and split it on the closing tag (once), so you'll now have two pieces in your new array. The new head is what was between your tags, and the new tail is the remainder of the string, which you may process again if the tag could appear more than once.
An example that may not be exactly correct but you get the idea:
head1, tail1 = str.split('<tag>', 1) # finds the opening tag
head2, tail2 = tail1.split('</tag>', 1) # finds the closing tag