I am extracting data from a forum. My script based on is working fine. Now I need to extract date and time (21 Dec 2009, 20:39) from single post. I cannot get it work. I used FireXPath to determine the xpath.
Sample code:
require 'rubygems'
require 'mechanize'
post_agent = WWW::Mechanize.new
post_page = post_agent.get('http://www.vbulletin.org/forum/showthread.php?t=230708')
puts post_page.parser.xpath('/html/body/div/div/div/div/div/table/tbody/tr/td/div[2]/text()').to_s.strip
puts post_page.parser.at_xpath('/html/body/div/div/div/div/div/table/tbody/tr/td/div[2]/text()').to_s.strip
puts post_page.parser.xpath('//[#id="post1960370"]/tbody/tr[1]/td/div[2]/text()')
all my attempts end with empty string or an error.
I cannot find any documentation on using Nokogiri within Mechanize. The Mechanize documentation says at the bottom of the page:
After you have used Mechanize to navigate to the page that you need to scrape, then scrape it using Nokogiri methods.
But what methods? Where can I read about them with samples and explained syntax? I did not find anything on Nokogiri's site either.
Radek. I'm going to show you how to fish.
When you call Mechanize::Page::parser, it's giving you the Nokogiri document. So your "xpath" and "at_xpath" calls are invoking Nokogiri. The problem is in your xpaths. In general, start out with the most general xpath you can get to work, and then narrow it down. So, for example, instead of this:
puts post_page.parser.xpath('/html/body/div/div/div/div/div/table/tbody/tr/td/div[2]/text()').to_s.strip
start with this:
puts post_page.parser.xpath('//table').to_html
This gets the any tables, anywhere, and then prints them as html. Examine the HTML, to see what tables it brought back. It probably grabbed several when you want only one, so you'll need to tell it how to pick out the one table you want. If, for example, you notice that the table you want has CSS class "userdata", then try this:
puts post_page.parser.xpath("//table[#class='userdata']").to_html
Any time you don't get back an array, you goofed up the xpath, so fix it before proceding. Once you're getting the table you want, then try to get the rows:
puts post_page.parser.xpath("//table[#class='userdata']//tr").to_html
If that worked, then take off the "to_html" and you now have an array of Nokogiri nodes, each one a table row.
And that's how you do it.
I think you have copied this from Firebug, firebug gives you an extra tbody, which might not be there in actual code... so my suggestion is to remove that tbody and try again.
if it still doesn't work ... then follow Wayne Conrad's process that's the best!
Related
I'm using Capybara with the Poltergeist driver. My question is: how to get the HTML (string) of a node?
I've read that using the RackTest driver you can get it like this:
find("table").native #=> native Nokogiri element
find("table").native.to_html #=> "..."
But with Poltergeist calling #native on a node returns a Capybara::Poltergeist::Node, not a native Nokogiri element. And then calling #native again on the Capybara::Poltergeist::Node returns the same Capybara::Poltergeist::Node again (that is, it returns self).
It has become slightly irritating having to look at the HTML from the entire page to find what I'm looking for :P
I am adding this answer for others who land here. The solution is dead simple.
following the example you provided it would be:
find("table")['outerHTML']
I also find Poltergeist irritating. Here's what I did:
def nokogiri(selector)
nokogiri = Nokogiri::HTML(page.html);
return nokogiri.css(selector)[0]
end
This takes a css selector, and returns a native nokogiri element, rather than poltergeist's idiocy. You'll also have to require 'nokogiri', but it shouldn't be a problem since it's a dependency for poltergeist.
Its can be done like this
lets say on google.co.in you wana fetch INDIA
on step.rb file under your function write this line
x = page.find(:xpath,'//*[#id="hplogo"]/div' , :visible => false).text
puts x
x will display "India"
Terminal o/p
The following works but is always very slow, seemingly halting my scraping program and its Firefox or Chrome browser for even whole minutes per page:
pp recArray = $browser.table(:id,"recordTable").to_a
Getting the HTML table's text or html source is fast though:
htmlcode = $browser.table(:id,"recordTable").html # .text shows only plaintext portion like lynx
How might I be able to create the same recArray (each element from a <TR>) using for example a Nokogiri object holding only that table's html?
recArray = Nokogiri::HTML(htmlcode). ??
I wrote a blog post about that a few days ago: http://zeljkofilipin.com/watir-nokogiri/
If you have further questions, ask.
You want each tr in the table?
Nokogiri::HTML($browser.html).css('table[#id="recordTable"] > tr')
This gives a NodeSet which can be more useful than Array. Of course there's still to_a
Thought it would be useful to sum up all the steps here and there:
The question was how to produce the same array object filled with strings from the page's text content that a Watir::Webdriver Table #to_a might produce, but much faster:
recArray = Nokogiri::HTML(htmlcode). **??**
So instead of this as I was doing before:
recArray=$browser.table(:class, 'detail-table w-Positions').to_a
I send the whole page's html as a string to Nokogiri to let it do the parsing:
recArray=Nokogiri::HTML($browser.html).css('table[#class="detail-table w-Positions"] tr').to_a
Which found me the rows of the table I want and put them into an array.
Not done yet since the elements of that array are still Nokogiri (Table Row?) types, which barfed when I attempted things like .join(",") (useful for writing into a .CSV file or database for instance)
So the following iterates through each row element, turning each into an array of pure Ruby String types, containing only the text content of each table cell stripped of html tags:
recArray= recArray.map {|row| row.css("td").map {|c| c.text}.to_a } # Could of course be merged with above to even longer, nastier one-liner
Each cell had previously also been a Nokogiri Element type, done away with the .text mapping.
Significant speedup achieved.
Next I wonder what it would take to simply override the #to_a method of every Watir::Webdriver Table object globally in my Ruby code files....
(I realize that may not be 100% compatible but it would spare me so much code rewriting. Am willing to try in my personal.lib.rb include file.)
I am new to nokogiri, but it looks like this would be the tool that I would use to scrape a webpage. I am looking for specific words on a webpage. The words are "Valid", "Requirements Met", and "Requirements Not". I am using watir to drive through the website. I currently have:
page = Nokogiri::HTML.parse(browser.html)
to get the html, but I am not sure where to go from here.
Thanks for the help!
If you are using Watir to drive the website, I would suggest using Watir to check for the text. You can get all the text on the page using:
ie.text #Where ie is a Watir::IE
You could then check to see if it has those words are included (by comparing to a regex):
if ie.text =~ /Valid|Requirements Met|Requirements Not/
#Do something if the words are on the page
end
That said, if you are looking for a specific bits of text, you can use Watir to look specifically for those elements (and avoid parsing text or html). If you can provide an HTML sample of what you are working on, we can help find a more robust solution.
I am not sure why you are using both. You could get the page using 'net/http' or mechanize if you just want to check for text. Anyways, you can check for text in watir with browser.text.match 'Valid', same for nokogiri with page.text.match 'Valid'.
You should also be able to use the .text method from Justin's answer along with the standard ruby string .include? method which returns true or false.
if browser.text.include? /Valid|Requirements Met|Requirements Not/
#code to execute if text found
else
#code to execute if text not found
end
This also makes it easy to have a single line validation step if that is what you are after
if using rspec/cucumber
browser.text.should include /Valid|Requirements Met|Requirements Not/
if using test:Unit
assert browser.text.include? /Valid|Requirements Met|Requirements Not/
I'm having an issue getting Nokogiri to work properly. I'm using version 1.4.4 with Ruby 1.9.2.
I have both libxml2 libxslt installed and up to date. When I run a Ruby script with XML, it works great.
require 'nokogiri'
doc = Nokogiri::XML(File.open("test.xml"))
doc = doc.css("name").each do |node|
puts node.text
end
Enter into the CL, run ruby test.rb, returns
Name 1
Name 2
Name 3
And the crowd goes wild.
I tweak a few things, make a few adjustments to the code...
require 'nokogiri'
require 'open-uri'
doc = Nokogiri::HTML(open("http://domain.tld"))
doc = doc.css("p").each do |node|
puts node.text
end
Back to CL, ruby test.rb, returns... nothing! Just a new, empty line.
Is there any reason that it will work with an XML file, but not HTML?
To debug this sort of problem we need more information from you. Since you're not giving a working URL, and because we know that Nokogiri works fine for this sort of problem, the debugging falls on you.
Here's what I would do to test:
In IRB:
Do you get output when you do: open('http://whateverURLyouarehiding.com').read
If that returns a valid document, what do you get when you wrap the previous open statement in Nokogiri::HTML(...). That needs to preserve the .read in the previous line too, so Nokogiri is receiving the body of the page, NOT an IO stream.
Try #2 above, but remove the .read. That will tell if there's a problem with Nokogiri reading an IO stream, though I seriously doubt it has a problem since I use it all the time. At that point I'd suspect a problem on your system.
If you're getting a document in #2 and #3, then the problem could be in your accessor; I suspect what you're looking for doesn't exist.
If it does exist, then check the value of doc.errors after Nokogiri parses the document. It could be finding errors in the document, and, if so, they'll be captured there.
I am by no means a master with Ruby and am quite new to Scrubyt. I was just trying out some examples found on there wiki page. The example i was working on was getting the search results returned by Google when you search for 'ruby' and I had the idea of grabbing the URL of each result so I could go ahead and fetch that page as well. The problem is I don't know how to grab the URL appropriately. This is my following code:
require 'rubygems'
require 'scrubyt'
google_data = Scrubyt::Extractor.define do
fetch 'http://www.google.com/ncr'
fill_textfield 'q','ruby'
submit
link_title "//a[#class='l']", :write_text => true do
link_url
end
end
google_data.to_xml.write($stdout, 1);
The code prints out the XML data appropriately (name and link) but how do I retrieve the link without the <link_url> tags that seems to get added to it (I tried to print out link_url and I noticed the tags are printed as well). Could I do something as simple as fetch link_url or is there a way of extracting the text from the xml content held in link_url?
This is some of the content that gets printed by the google_data.to_xml.write():
<root>
<link_title>
Ruby Programming Language
<link_url>http://ruby-lang.org/</link_url>
</link_title>
<link_title>
Download Ruby
<link_url>http://www.ruby-lang.org/en/downloads/</link_url>
</link_title>
<link_title>
Ruby - The Inspirational Weight Loss Journey on the Style Network ...
<link_url>http://www.mystyle.com/mystyle/shows/ruby/index.jsp</link_url>
</link_title>
<link_title>
Ruby (programming language) - Wikipedia, the free encyclopedia
<link_url>http://en.wikipedia.org/wiki/Ruby_(programming_language)</link_url>
</link_title>
</root>
I'd think about alternatives. Scrubyt hasn't been updated in a while, and the forums have been shut down.
Mechanize can do what the Extractor does, Nokogiri can parse XML or HTML responses, and Builder can create XML (though it seems like you don't really want XML).