The xml_serializer plugin handles serializing entire Sequel::Model objects to XML, and deserializing XML into a single Sequel::Model object or an array of Sequel::Model objects. It requires the nokogiri library.
Basic Example:
album = Album[1] puts album.to_xml # Output: <?xml version="1.0"?> <album> <id>1</id> <name>RF</name> <artist_id>2</artist_id> </album>
You can provide options to control the XML output:
puts album.to_xml(:only=>:name) puts album.to_xml(:except=>[:id, :artist_id]) # Output: <xml version="1.0"?> <album> <name>RF</name> </album> album.to_xml(:include=>:artist) # Output: <xml version="1.0"?> <album> <id>1</id> <name>RF</ame> <artist_id>2</artist_id> <artist> <id>2</d> <name>YJM</name> </artist> </album>
You can use a hash value with :include to pass options to
associations:
album.to_xml(:include=>{:artist=>{:only=>:name}}) # Output: <xml version="1.0"?> <album> <id>1</id> <name>RF</ame> <artist_id>2</artist_id> <artist> <name>YJM</ame> </artist> </album>
to_xml also exists as a class and dataset method, both of
which return all objects in the dataset:
Album.to_xml Album.filter(:artist_id=>1).to_xml(:include=>:tags)
If you have an existing array of model instances you want to convert to XML, you can call the class to_xml method with the :array option:
Album.to_xml(:array=>[Album[1], Album[2]])
In addition to creating XML, this plugin also enables Sequel::Model classes to create instances directly from XML using the from_xml class method:
xml = album.to_xml album = Album.from_xml(xml)
The array_from_xml class method exists to parse arrays of model instances from xml:
xml = Album.filter(:artist_id=>1).to_xml albums = Album.array_from_xml(xml)
These does not necessarily round trip, since doing so would let users create model objects with arbitrary values. By default, from_xml will call set using values from the tags in the xml. If you want to specify the allowed fields, you can use the :fields option, which will call set_fields with the given fields:
Album.from_xml(album.to_xml, :fields=>%wid name')
If you want to update an existing instance, you can use the from_xml instance method:
album.from_xml(xml)
Both of these allow creation of cached associated objects, if you provide the :associations option:
album.from_xml(xml, :associations=>:artist)
You can even provide options when setting up the associated objects:
album.from_xml(xml, :associations=>{:artist=>{:fields=>%wid name', :associations=>:tags}})
Usage:
# Add XML output capability to all model subclass instances (called before loading subclasses) Sequel::Model.plugin :xml_serializer # Add XML output capability to Album class instances Album.plugin :xml_serializer