DDEX¶ ↑

DDEX metadata serialization for Ruby

Overview¶ ↑

require "ddex"

message = DDEX.read("path/to/metadata.xml")
puts message.update_indicator
message.resource_list.each do |resource|
  puts resource.title
  puts resource.details.size
end

puts "Supported!" if DDEX.supports?("ern/341")

message = DDEX.read(string)
message = DDEX.read(io)
# ...

include DDEX::ERN::V341   # v3.4.1
message = NewReleaseMessage.new(hash)
record  = SoundRecording.new
record.language_and_script_code = "en-US"
# ...

image = Image.new
image.type = "FrontCoverImage"
# ...

message.resource_list << image
message.resource_list << record
p message.to_hash

xml = DDEX.write(message)
File.open("bloat.xml", "w") { |io| io.puts(xml) }

How this differs from the spec¶ ↑

Every DDEX version handled by this module is fully supported, but there are some things you’ll need to know.

Naming conventions¶ ↑

DDEX elements and attributes use the CamelCase naming convention, this module uses Ruby naming conversions: CamelCase for classes, and snake_case for class attributes. For example, this DDEX XML:

<PartyName>
  <FullName>sshaw</FullName>
</PartyName>

Would be manipulated via:

party = PartyName.new(:full_name => "sshaw")
puts party.full_name
party.full_name = "gwozdzie"

See also Boolean elements and attributes

Cardinally¶ ↑

Elements that can occur more than once will be placed in an Array and their parent classes’ accessor methods will use the plural form of the element/attribute’s name. For example:

<Release>
  <!-- More data -->
  <PLine>
    <Year>1994</Year>
    <PLineText>Track Copyright</PLineText>
  </PLine>
  <PLine>
    <Year>2001</Year>
    <PLineText>Another Track Copyright</PLineText>
  </PLine>
</Release>

Would be manipulated via:

release.p_lines.each { |line| puts line.p_line_text }
release.p_lines << PLine.new(:year => 1999)

There are a few -hopefully obvious- exceptions. If the DDEX name indicates that its a collection, it’s left alone. SoundRecordingDetailsByTerritory and ResourceList come to mind.

Boolean elements and attributes¶ ↑

The following are applied to accessors derived from DDEX elements and attributes with an XML schema type of boolean:

"Is" is removed from the beginning of the name
The reader method is turned into a predicate accessor, i.e., has a "?" appended to it

For example, SoundRecording/IsArtistRelated:

recording = SoundRecording.new(:artist_related => true)
p recording.artist_related?  # true
recording.artist_related = false

TODO: See Types

Version specific changes¶ ↑

ERN v3.6¶ ↑

ern:PriceInformation/@PriceType has been renamed to @Type to avoid conflicting with the element of the same name (ern:PriceInformation/PriceType)

More Info¶ ↑

Source code
Bugs
jaxb2ruby (Generate Ruby objects from an XML schema)
DDEX Schemas

TODO¶ ↑

Many things… but: ROXML.from_xml does not check the root element’s name. Need to add something like:

raise "unknown element #{xml.name}" unless xml.name == tag_name

naffis / ddex