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</name> # <artist_id>2</artist_id> # <artist> # <id>2</id> # <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</name> # <artist_id>2</artist_id> # <artist> # <name>YJM</name> # </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.where(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.where(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: %w'id 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: %w'id 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