dm-serializer allows DataMapper models and collections to be serialized to a variety of formats (currently JSON, XML, YAML and CSV).
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.
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 => [:description]) # => { "id": 1, "name": "Berta", "description": "A Cow" }
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:
require 'dm-serializer/to_json'
to_xml supports some extra options to allow you to override the element names
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>
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.
to_csv currently doesn’t support any options yet. It will in the future. It will not support serializing child associations.
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*.
Cow.all.to_a.to_yaml(:only => 'name') # WILL NOT WORK
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.