mattsears / with_xml

A simple rails plugin for the xml serialization of ActiveRecord objects with various xml schemas

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Added README in Markdown mode
mattsears (author)
Mon May 25 18:48:39 -0700 2009
commit  9412719671586259d05ed2b12e868a4c978a513b
tree    9c2d37aadf092b1141b457e1aa23e4bdb030be26
parent  8dbb90b4b27b90643a4521f9a75a6c56ed0b4ab3
README.md

with_xml

A simple plugin for customizing behaviour and importing xml documents into ActiveRecord objects.

Installation

script/plugin install git://github.com/mattsears/with_xml.git

Usage

In general, you can define the xml options in the model's class definition. In this example, we'll set the xml options in the Article class:

ActiveRecord::Schema.define(:version => 1) do
  create_table :articles do |t|
  t.string :name, :heading, :body, :author
end

In the Article's class, we define the xml serialization options in the with_xml block like so:

class Article < ActiveRecord::Base
  with_xml :feeds, {:alias  => ["magazine", "blog", "newspaper"]} do
    map :heading,   :to     => ["subject", "title"]
    map :body,      :to     => ["content", "message", "posts[@content='body']"]
    serialize       :except => [:name], :skip_instruct => true
  end
end

With the serialize option, the script sets the global options for the to_xml calls. In the code above, we've specified not to include the :name attribute or the xml instructions in the xml return from the to_xml call.

article.to_xml

...becomes...

#<article>
#    <author>...</author>
#    <body>...</body>
#    <heading>...</heading>
#</article>

The map options allows us to set the Article attributes with an xml string that has a different schema. For example, data for our Article class may come from external sources such as blogs, magazines or newspapers with different xml schemas. We can use XPath to map the xml attributes or elements to the class attributes. With the map options in the code above, we can import any of the following xml documents into the Article:

article.from_xml(xml)

#<article>
#    <heading>Page Six</heading>
#    <body>Content for article</body>
#</article>

#<magazine>
#   <title>The Washington Post</title>
#   <content>This is the content</content>
#</magazine>

#<blog>
#   <title>TechCrunch</title>
#   <post>The Post</post>
#</blog>

#<newspaper>
#   <title>The Wall Street Journal</title>
#   <content>This is the content</content>
#   <unknown>There is no field for this element.  It will be ignored.</unknown>
#   <AUTHOR>Caps will be  by default</AUTHOR>
#</newspaper>

Contact

Author:      Matt Sears
Email:       matt@mattsears.com
Home Page:   http://mattsears.com
License:     MIT Licence (http://www.opensource.org/licenses/mit-license.html)