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Apparently Nokogiri's add_class method only works on NodeLists, making this code invalid:
doc.search('a').each do |anchor|
anchor.inner_text = "hello!"
anchor.add_class("whatever") # WHOOPS!
end
What can I do to make this code work? I figured it'd be something like
doc.search('a').each do |anchor|
anchor.inner_text = "hello!"
Nokogiri::XML::NodeSet.new(anchor).add_class("whatever")
end
but this doesn't work either. Please tell me I don't have to implement my own add_class for single nodes!
853
A CSS class is just another attribute on an element:
doc.search('a').each do |anchor|
anchor.inner_text = "hello!"
anchor['class']="whatever"
end
Since CSS classes are space-delimited in the attribute, if you're not sure if one or more classes might already exist you'll need something like
anchor['class'] ||= ""
anchor['class'] = anchor['class'] << " whatever"
You need to explicitly set the attribute using = instead of just mutating the string returned for the attribute. This, for example, will not change the DOM:
anchor['class'] ||= ""
anchor['class'] << " whatever"
Even though it results in more work being done, I'd probably do this like so:
class Nokogiri::XML::Node
def add_css_class( *classes )
existing = (self['class'] || "").split(/\s+/)
self['class'] = existing.concat(classes).uniq.join(" ")
end
end
If you don't want to monkey-patch the class, you could alternatively:
module ClassMutator
def add_css_class( *classes )
existing = (self['class'] || "").split(/\s+/)
self['class'] = existing.concat(classes).uniq.join(" ")
end
end
anchor.extend ClassMutator
anchor.add_css_class "whatever"
Edit: You can see that this is basically what Nokogiri does internally for the add_class method you found by clicking on the class to view the source:
# File lib/nokogiri/xml/node_set.rb, line 136
def add_class name
each do |el|
next unless el.respond_to? :get_attribute
classes = el.get_attribute('class').to_s.split(" ")
el.set_attribute('class', classes.push(name).uniq.join(" "))
end
self
end
Nokogiri's add_class, works on a NodeSet, like you found. Trying to add the class inside the each block wouldn't work though, because at that point you are working on an individual node.
Instead:
require 'nokogiri'
html = '<p>one</p><p>two</p>'
doc = Nokogiri::HTML(html)
doc.search('p').tap{ |ns| ns.add_class('boo') }.each do |n|
puts n.text
end
puts doc.to_html
Which outputs:
# >> one
# >> two
# >> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
# >> <html><body>
# >> <p class="boo">one</p>
# >> <p class="boo">two</p>
# >> </body></html>
The tap method, implemented in Ruby 1.9+, gives access to the nodelist itself, allowing the add_class method to add the "boo" class to the <p> tags.
3
Old thread, but it's the top Google hit. You can now do this with the append_class method without having to mess with space-delimiters:
doc.search('a').each do |anchor|
anchor.inner_text = "hello!"
anchor.append_class('whatever')
end
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