CSS/Xpath sibling selector in Nokogiri - ruby

I have the following XML tree and need to get out the first name and surname only for the contrib tags with child xref nodes of ref-type "corresp".
<pmc-articleset>
<article>
<front>
<article-meta>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>Wereszczynski</surname>
<given-names>Jeff</given-names>
</name>
<xref rid="aff1" ref-type="aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Andricioaei</surname>
<given-names>Ioan</given-names>
</name>
<xref rid="aff1" ref-type="aff"/>
<xref ref-type="corresp" rid="cor1">*</xref>
</contrib>
</contrib-group>
</article-meta>
</front>
</article>
</pmc-articleset>
I saw "Getting the siblings of a node with Nokogiri" which points out the CSS sibling selectors that can be used in Nokogiri, but, following the example given, my code gives siblings indiscriminately.
require "Net/http"
require "nokogiri"
url = "http://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?id=PMC1637560&db=pmc"
xml_data = Net::HTTP.get_response(URI.parse(url)).body
parsedoc = Nokogiri::XML.parse(xml_data)
corrdetails = parsedoc.at('contrib:has(xref[text()="*"])')
puts surname = corrdetails.xpath( "//surname" ).text
puts givennames = corrdetails.xpath("//given-names").text
=> WereszczynskiAndricioaei
=> JeffIoan
I only want the sibling node under the condition that <xref ref-type="corresp">*</> , that is an output of:
=> Andricioaei
=> Ioan
I've currently implemented this without referring to ref-type but rather selecting the asterisk within the xref tag (either is appropriate).

The problem is actually with your XPath for getting the the surname and given name, i.e., the XPath is incorrect for the lines:
puts surname = corrdetails.xpath( "//surname" ).text
puts givennames = corrdetails.xpath("//given-names").text
Starting the XPath with // means to look for the node anywhere in the document. You only want to look within the corrdetails node, which means the XPath needs to start with a dot, e.g., .//.
Change the two lines to:
puts surname = corrdetails.xpath( ".//surname" ).text
puts givennames = corrdetails.xpath(".//given-names").text

Related

Can I use Selenium and Nokogiri to locate an element based on a nearby label?

Let's say I want to scrape the "Weight" attribute from the following content on a website:
<div>
<h2>Details</h2>
<ul>
<li><b>Height:</b>6 ft</li>
<li><b>Weight:</b>6 kg</li>
<li><b>Age:</b>6</li>
</ul>
</div>
All I want is "6 kg". But it's not labeled, and neither is anything around it. But I know that I always want the text after "Weight:". Is there a way of selecting an element based on the text near it or in it?
In pseudocode, this is what it might look like:
require 'selenium-webdriver'
require 'nokogiri'
doc = parsed document
div_of_interest = doc.div where text of h2 == "Details"
element_of_interest = <li> element in div_of_interest with content that contains the string "Weight:"
selected_text = (content in element) minus ("<b>Weight:</b>")
Is this possible?
You can write the following code
p driver.find_elements(xpath: "//li").detect{|li| li.text.include?'Weight'}.text[/:(.*)/,1]
output
"6 kg"
My suggestion is to use WATIR which is wrapper around Ruby Selenium Binding where you can easily write the following code
p b.li(text: /Weight/).text[/:(.*)/,1]
Yes.
require 'nokogiri'
Nokogiri::HTML.parse(File.read(path_to_file))
.css("div > ul > li")
.children # get the 'li' items
.each_slice(2) # pair a 'b' item and the text following it
.find{|b, text| b.text == "Weight:"}
.last # extract the text element
.text
will return
"6 kg"
You can locate the element through pure xpath: use the contains() function which returns Boolean is its second argument found in the first, and pass to it text() (which returns the text of the node) and the target string.
xpath_locator = '/div/ul/li[contains(text(), "Weight:")]'
value = driver.find_element(:xpath, xpath_locator).text.partition('Weight:').last
Then just get the value after "Weight:".

How can I extract the node names for fragmented XML document using Ruby?

I an XML-like document which is pre-processed by a system out of my control. The format of the document is like this:
<template>
Hello, there <RECALL>first_name</RECALL>. Thanks for giving me your email.
<SETPROFILE><NAME>email</NAME><VALUE><star/></VALUE></SETPROFILE>. I have just sent you something.
</template>
However, I only get as a text string what is between the <template> tags.
I would like to be able to extract without specifying the tags ahead of time when parsing. I can do this with the Crack gem but only if the tags are at the end of the string and there is only one.
With Crack, I can put a string like
string = "<SETPROFILE><NAME>email</NAME><VALUE>go#go.com</VALUE></SETPROFILE>"
and my output from Crack is:
{"SETPROFILE"=>{"NAME"=>"email", "VALUE"=>"go#go.com"}}
Then I can use a case statement for the possible values I care about.
Given that I need to have multiple <tags> in the string and they cannot be at the end of the string, how can I parse out the node names and the values easily, similar to what I do with crack?
These tags also need to be removed. I would like to continue to use the excellent suggestion from #TinMan.
It works perfectly once I know the name of the tag. The number of tags will be finite. I send the tag to the appropriate method once I know it, but it needs to get parsed out easily first.
Using Nokogiri, you can treat the string as a DocumentFragment, then find the embedded nodes:
require 'nokogiri'
doc = Nokogiri::XML::DocumentFragment.parse(<<EOT)
Hello, there <RECALL>first_name</RECALL>. Thanks for giving me your email.
<SETPROFILE><NAME>email</NAME><VALUE><star/></VALUE></SETPROFILE>. I have just sent you something.
EOT
nodes = doc.search('*').each_with_object({}){ |n, h|
h[n] = n.text
}
nodes # => {#<Nokogiri::XML::Element:0x3ff96083b744 name="RECALL" children=[#<Nokogiri::XML::Text:0x3ff96083a09c "first_name">]>=>"first_name", #<Nokogiri::XML::Element:0x3ff96083b5c8 name="SETPROFILE" children=[#<Nokogiri::XML::Element:0x3ff96083a678 name="NAME" children=[#<Nokogiri::XML::Text:0x3ff960836884 "email">]>, #<Nokogiri::XML::Element:0x3ff96083a650 name="VALUE" children=[#<Nokogiri::XML::Element:0x3ff96083a5c4 name="star">]>]>=>"email", #<Nokogiri::XML::Element:0x3ff96083a678 name="NAME" children=[#<Nokogiri::XML::Text:0x3ff960836884 "email">]>=>"email", #<Nokogiri::XML::Element:0x3ff96083a650 name="VALUE" children=[#<Nokogiri::XML::Element:0x3ff96083a5c4 name="star">]>=>"", #<Nokogiri::XML::Element:0x3ff96083a5c4 name="star">=>""}
Or, more legibly:
nodes = doc.search('*').each_with_object({}){ |n, h|
h[n.name] = n.text
}
nodes # => {"RECALL"=>"first_name", "SETPROFILE"=>"email", "NAME"=>"email", "VALUE"=>"", "star"=>""}
Getting the content of a particular tag is easy then:
nodes['RECALL'] # => "first_name"
Iterating over all the tags is also easy:
nodes.keys.each do |k|
...
end
You can even replace a tag and its content with text:
doc.at('RECALL').replace('Fred')
doc.to_xml # => "Hello, there Fred. Thanks for giving me your email. \n<SETPROFILE>\n <NAME>email</NAME>\n <VALUE>\n <star/>\n </VALUE>\n</SETPROFILE>. I have just sent you something.\n"
How to replace the nested tags is left to you as an exercise.

Get a specific tag in a node?

I'm using Ruby, XPath and Nokogiri and trying to retrieve d1 from the following XML:
<a>
<b1>
<c>
<d1>01/11/2001</d1>
<d2>02/02/2004</d2>
</c>
</b1>
</a>
This is my code in a loop:
rs = doc.xpath("//a/b1/c/d1").inner_text
puts rs
It returns nothing (No error).
I want to get the text in <d1>.
You don't ask for the text content in your xpath query:
rs = doc.xpath('//a/b1/c/d1/text()')
You're misusing XPath:
require 'nokogiri'
doc = Nokogiri::XML(<<EOT)
<a>
<b1>
<c>
<d1>01/11/2001</d1>
<d2>02/02/2004</d2>
</c>
</b1>
</a>
EOT
doc.at('/a/b1/c/d1').text # => "01/11/2001"
doc.at('//d1').text # => "01/11/2001"
// in XPath-ese means start at the top and look anywhere in your document. Instead, if you're supplying an explicit/absolute selector, start at the top of the document and drill down using '/a/b1/c/d1'. Or, do the simple thing and let the parser search through the document for that particular node using //d1. You can do that if you know there's a single instance of that node.
In my code above, I used at instead of xpath. at returns the first matching node, which is similar to using xpath('//d1').first. xpath returns a NodeSet, which is like an array of nodes, whereas at returns a Node only. Using inner_text on a NodeSet is likely to not give you the results you want, which would be the text of a particular node, so be careful there.
doc.xpath('/a/b1/c/d1/text()').class # => Nokogiri::XML::NodeSet
doc.xpath('//c').inner_text # => "\n 01/11/2001\n 02/02/2004\n "
doc.xpath('/a/b1/c/d1').first.text # => "01/11/2001"
Look at the following lines. Instead of using XPath selectors, I used CSS, which tends to be more readable. Nokogiri supports both.
doc.at('d1').text # => "01/11/2001"
doc.at('a b1 c d1').text # => "01/11/2001"
Also, notice the type of data returned from these two lines:
doc.at('/a/b1/c/d1/text()').class # => Nokogiri::XML::Text
doc.at('/a/b1/c/d1').text.class # => String
While it might seem good/smart to tell the parser to locate the text() node inside <d1>, what will be returned isn't text, and will need to be accessed further to make it usable, so consider forgoing the use of text() unless you know exactly why you need it:
doc.at('/a/b1/c/d1/text()').text # => "01/11/2001"
Finally, Nokogiri has many methods used for locating nodes. As I said above, xpath returns a NodeSet and at returns a Node. xpath is really an XPath-specific version of Nokogiri's search method. search, css and xpath all return NodeSets. at, at_css and at_xpath all return Nodes. The CSS and XPath variants are useful when you have an ambiguous selector that you need to be used as CSS or XPath specifically. Most of the time Nokogiri can figure whether it's CSS or XPath on its own and will do the right thing, so it's OK to use the generic search and at for the majority of your coding. Use the specific versions when you have to specify one or the other.

Searching for tags while parsing Wordpress XML with Nokogiri

I have an XML file of a Wordpress blog that consists of quotes:
<item>
<title>Brothers Karamazov</title>
<content:encoded><![CDATA["I think that if the Devil doesn't exist and, consequently, man has created him, he has created him in his own image and likeness."]]></content:encoded>
<category domain="post_tag" nicename="dostoyevsky"><![CDATA[Dostoyevsky]]></category>
<category domain="post_tag" nicename="humanity"><![CDATA[humanity]]></category>
<category domain="category" nicename="quotes"><![CDATA[quotes]]></category>
<category domain="post_tag" nicename="the-devil"><![CDATA[the Devil]]></category>
</item>
The things I'm trying to extract are title, author, content and tags. Here's my code so far:
require "rubygems"
require "nokogiri"
doc = Nokogiri::XML(File.open("/Users/charliekim/Downloads/quotesfromtheunderground.wordpress.2013-04-14.xml"))
doc.css("item").each do |item|
title = item.at_css("title").text
tag = item.at_xpath("category").text
content = item.at_xpath("content:encoded").text
#each post will later be pushed to an array, but I'm not worried about that yet, so for now....
puts "#{title} #{tag}"
end
I'm struggling to get all the tags from each item. I'm getting returns of something like Brothers Karamazov Dostoyevsky. I'm not worried about how it's formatted as it's only a test to see that it's picking things up correctly. Anyone know how I can go about this?
I also want to make tags that are capitalized = Author, so if you know how to do that it would help, too, although I haven't even tried it yet.
EDIT: I changed the code to this:
doc.css("item").each do |item|
title = item.at_css("title").text
content = item.at_xpath("content:encoded").text
tag = item.at_xpath("category").each do |category|
category
end
puts "#{title}: #{tag}"
end
which returns:
Brothers Karamazov: [#<Nokogiri::XML::Attr:0x80878518 name="domain" value="post_tag">, #<Nokogiri::XML::Attr:0x80878504 name="nicename" value="dostoyevsky">]
and which seems a bit more manageable. It screws up my plans for taking the Author from a capitalized tag, but, well, it's not so big of a deal. How could I pull just the second value?
You're using at_xpath and expecting it to return more than one result, when the at_ methods only return the first result.
You want something like:
tags = item.xpath("category").map(&:text)
which will return an array.
As for identifying the author, you can use a regex to select the items that start with a capital letter:
author = tags.select{|w| w =~ /^[A-Z]/}
Which will choose any capitalized tags. This leaves the tags untouched. If you wanted instead to separate the authors from the tags, you can use partition:
author, tags = item.xpath("category").map(&:text).partition{|w| w =~ /^[A-Z]/}
Note that in the above examples, author is an array and will contain all matching items (i.e. more than one capitalized tag).

why can't i wrap <span> around the rfollowing nokogiri xpath?

doc = Nokogiri::HTML(open(url)).xpath("//*")
.xpath("//*[br]/text()[string-length(normalize-space()) != 0]")
.wrap("<span></span>")
puts doc
it just returns the text ... i was expecting the full html source with now wrapped around the specified xpath elements.
Try
doc = Nokogiri::HTML(open(url)).xpath("//*")
.xpath("//*[br and text()[string-length(normalize-space()) != 0]]")
.wrap("<span></span>")
puts doc
What your XPath does is it fetches the non-empty text nodes. Which by their very definition don't contain any markup.
In contrast, my XPath fetches any node that contains at least one <br> and at least one non-empty text node.

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