Write to XML in ruby

Question

I am completely new to Ruby. All I want is to produce a simple XML file.

<?xml version="1.0" encoding="ASCII"?>
<product>
   <name>Test</name>
</product>

That's it.

Solution 1

Builder should probably be your first stopping point:

require 'builder'

def product_xml
  xml = Builder::XmlMarkup.new( :indent => 2 )
  xml.instruct! :xml, :encoding => "ASCII"
  xml.product do |p|
    p.name "Test"
  end
end

puts product_xml

produces this:

<?xml version="1.0" encoding="ASCII"?>
<product>
  <name>Test</name>
</product>

which looks about right to me.

Some Builder references:

• author's (Jim Weirich) original blog post
• API docs
• article at XML.com

Solution 2

Simply with Nokogiri::XML::Builder

require 'nokogiri'

builder = Nokogiri::XML::Builder.new(:encoding => 'UTF-8') do |xml|
  xml.root {
    xml.products {
      xml.widget {
        xml.id_ "10"
        xml.name "Awesome widget"
      }
    }
  }
end
puts builder.to_xml

Will output:

<?xml version="1.0" encoding="UTF-8"?>
<root>
  <products>
    <widget>
      <id>10</id>
      <name>Awesome widget</name>
    </widget>
  </products>
</root>

Solution 3

You can use builder to generate xml.

Solution 4

Here are a couple more options for constructing XML in Ruby

REXML - built-in but is very slow especially when dealing with large documents

Nokogiri - newer and faster, installs as a rubygem

LibXML-Ruby - built on the C libxml library, also installs as a rubygem

If you can't install rubygems then REXML is your best options. If you are going to be creating large complex XML docs then Nokogiri or LibXML-Ruby is what you would want to use.

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Comments

[ocodo]

All these are really for parsing existing xml, you should use Builder to create xml.

[froderik]

nokogiri got a builder also - not sure if it is any better but if you are doing both parsing and writing it may be sweet to use the same lib.

[PatrickWalker]

Nokogiris builder seems focused on blocks. It does work but I've found Builder very helpful with building xml programatically

[FilBot3]

This is probably the most simple example of Nokogiri I've seen yet. Awesome.

[pioto]

The API docs link seems to be dead (I think rubyforge.org itself is no more?). Is there an updated link available?

[David Tresner-Kirsch]

@pioto docs are available at github.com/jimweirich/builder -- I've proposed an edit fixing the link in the original post, but it's pending review.