Path: | README.textile |
Last Update: | Sun Mar 01 02:55:42 -0700 2009 |
h1. dm-serializer
h2. Overview
dm-serializer allows DataMapper models and collections to be serialized to a variety of formats (currently JSON, XML, YAML and CSV).
h2. How it works
One method is added to each model/collection for each serialization type - @to_json@, @to_xml@, @to_yaml@, and @to_csv@. With the exception of @to_csv@, all of these methods share the same interface. @to_json@ will be used for examples. Any method specific behaviour is documented in its own section below.
<pre><code>require ‘dm-serializer‘
class Cow
include DataMapper::Resource property :id, Integer, :key => true property :name, String def description "A Cow" end
end
cow = Cow.create(
:id => 1, :name => "Berta"
)
cow.to_json # => { "id": 1, "name": "Berta" } cow.to_json(:only => [:name]) # => { "name": "Berta" } cow.to_json(:exclude => [:id]) # => { "name": "Berta" } cow.to_json(:methods => [:desc]) # => { "id": 1, "name": "Berta", "desc": "A Cow" }</code></pre>
You can include associations by passing the association accessor the @:methods@ option.
If you want to only load a particular serialization method, that‘s cool, you can do that:
<pre>require ‘dm-serializer/to_json‘</pre>
h2. to_xml
@to_xml@ supports some extra options to allow you to override the element names
<pre>cow.to_xml( :element_name => ‘bovine’) # => <bovine><id>1</id><name>Berta</name></bovine> cows.to_xml(:collection_element_name => ‘kine’) # => <kine><bovine><id>1</id><name>Berta</name></bovine></kine></pre>
If you would like a nice speed boost (~5x), require @libxml@ or @nokogiri@ before @dm-serializer@, and that library will be used rather than REXML.
h2. to_csv
@to_csv@ currently doesn‘t support any options yet. It will in the future. It will not support serializing child associations.
h2. Arrays, Hashes, and other core classes
@dm-serializer@ only adds serialization methods to DataMapper objects and collections, however some libraries used (json, yaml) add methods to core classes, such as @Array@. Note that passing @dm-serializer@ options (such as @:only@) to these methods is *not supported*.
<pre>Cow.all.to_a.to_yaml(:only => ‘name’) # WILL NOT WORK</pre>
h2. Beware
If you go spelunking through the code you will find other undocumented options. Use at your own risk, I plan on removing or changing these in the near future.