How do I remove white space between HTML nodes? - ruby-on-rails

Question

I'm trying to remove whitespace from an HTML fragment between <p> tags
<p>Foo Bar</p> <p>bar bar bar</p> <p>bla</p>
as you can see, there always is a blank space between the <p> </p> tags.
The problem is that the blank spaces create <br> tags when saving the string into my database.
Methods like strip or gsub only remove the whitespace in the nodes, resulting in:
<p>FooBar</p> <p>barbarbar</p> <p>bla</p>
whereas I'd like to have:
<p>Foo Bar</p><p>bar bar bar</p><p>bla</p>
I'm using:
Nokogiri 1.5.6
Ruby 1.9.3
Rails
UPDATE:
Occasionally there are children nodes of the <p>Tags that generate the same problem: white space between
Sample Code
Note: the Code normally is in one Line, I reformatted it because it would be unbearable otherwise...
<p>
<p>
<strong>Selling an Appartment</strong>
</p>
<ul>
<li>
<p>beautiful apartment!</p>
</li>
<li>
<p>near the train station</p>
</li>
.
.
.
</ul>
<ul>
<li>
<p>10 minutes away from a shopping mall </p>
</li>
<li>
<p>nice view</p>
</li>
</ul>
.
.
.
</p>
How would I strip those white spaces aswell?
SOLUTION
It turns out that I messed up using the gsub method and didn't further investigate the possibility of using gsub with regex...
The simple solution was adding
data = data.gsub(/>\s+</, "><")
It deleted whitespace between all different kinds of nodes... Regex ftw!

Answer 1

This is how I'd write the code:
require 'nokogiri'
doc = Nokogiri::HTML::DocumentFragment.parse(<<EOT)
<p>Foo Bar</p> <p>bar bar bar</p> <p>bla</p>
EOT
doc.search('p, ul, li').each { |node|
next_node = node.next_sibling
next_node.remove if next_node && next_node.text.strip == ''
}
puts doc.to_html
It results in:
<p>Foo Bar</p><p>bar bar bar</p><p>bla</p>
Breaking it down:
doc.search('p')
looks for only the <p> nodes in the document. Nokogiri returns a NodeSet from search, or a nil if nothing matched. The code loops over the NodeSet, looking at each node in turn.
next_node = node.next_sibling
gets the pointer to the next node following the current <p> node.
next_node.remove if next_node && next_node.text.strip == ''
next_node.remove removes the current next_node from the DOM if the next node isn't nil and its text isn't empty when stripped, in otherwords, if the node has only whitespace.
There are other techniques to locate only the TextNodes if all of them should be stripped from the document. That's risky, because it can end up deleting all blanks between tags, causing run-on sentences and joined words, which probably isn't what you want.

Answer 2

A first solution can be to remove empty text nodes, a quick way to do this for your exact case can be:
require 'nokogiri'
doc = Nokogiri::HTML("<p>Foo Bar</p> <p>bar bar bar</p> <p>bla</p>")
doc.css('body').first.children.map{|node| node.to_s.strip}.compact.join
This won't work for nested elements as-is but should give you a good path for start.
UPDATE:
You can actually optimise a little with:
require 'nokogiri'
doc = Nokogiri::HTML::DocumentFragment.parse("<p>Foo Bar</p> <p>bar bar bar</p> <p>bla</p>")
doc.children.map{|node| node.to_s.strip}.compact.join

Answer 3

Here is all the possible task you can be looking for which deals with unnecessary whitespaces(including unicode one) in parsing output.
html = "<p>A paragraph.<em> </em> <br><br><em>
</em></p><p><em> </em>
</p><p><em>
</em><strong><em>\" Quoted Text \" </em></strong></p>
<ul><li><p>List 1</p></li><li><p>List 2</p></li><li><p>List 3 </p>
<p><br></p><p><br><em> </em><br>
A text content.<br><em><br>
</em></p></li></ul>"
doc = Nokogiri::HTML.fragment(html)
doc.traverse { |node|
# removes any whitespace node
node.remove if node.text.gsub(/[[:space:]]/, '') == ''
# replace mutiple consecutive spaces with single space
node.content = node.text.gsub(/[[:space:]]{2,}/, ' ') if node.text?
}
# Gives you html without any text node including <br> or multiple spaces anywhere in the text of html
puts doc.to_html
# Gives text of html, concatenating li items with a space between them
# By default li items text are concatenated without the space
Nokogiri::HTML(doc.to_html).xpath('//text()').map(&:text).join(' ')
#Output
# "A paragraph. \" Quoted Text \" \n List 1 \n List 2 \n \n List 3 \n A text content. \n \n"
# To Remove newline character '\n'
Nokogiri::HTML(doc.to_html).xpath('//text()').map(&:text).join(' ').gsub(/\n+/,'')
#Output
# "A paragraph. \" Quoted Text \" List 1 List 2 List 3 A text content."
Note: If you are not using fragment in case of a complete html doc then you might have to replace traverse with other function like search.

Answer 4

data.squish does the same thing and is way more readable.