RDF::DataObjects

DataObjects-backed RDF.rb repository, aiming for a simple use case and currently targeting SQLite and Postgres.

Gem Version Build Status

This was written for a tutorial, and is thus a pretty naive implementation so far. RDF::DataObjects stores triples in a simple subject, predicate, object, context table. Don't try to back a big website with it yet. Nonetheless, it works, and it passes all its tests on Heroku as well.

Example:

repository = RDF::DataObjects::Repository.new "sqlite3:test.db"
repository.insert(statement)
repository.count              #=> 1
repository.delete(statement)

You can use any DataObjects compatible connection options to create a new repository, but only SQLite3 and Postgres are implemented for now. The different databases are just different enough with their handling of unique constraints that some database-specific work is required for a new adapter, but it's not much.

Installation

The greatly preferred installation method is via RubyGems:

$ sudo gem install rdf-do

Requires Ruby >= 1.9.2

Connecting

require 'rdf'
require 'rdf/do'
require 'do_postgres' # gem install do_postgres
require 'do_sqlite3'  # gem install do_sqlite3
repo = RDF::DataObjects::Repository.new "postgres://localhost/database"
repo = RDF::DataObjects::Repository.new "sqlite3:test.db"

Using

Your repository is a fully-functional RDF.rb RDF::Repository. As with any RDF.rb repository, this includes the mixins RDF::Enumerable, RDF::Mutable, RDF::Durable, and RDF::Queryable. Please see http://rdf.rubyforge.org/RDF/Repository.html for more information.

Example:

require 'rdf'
require 'rdf/ntriples'
require 'data_objects'
require 'do_sqlite3'
require 'rdf/do'

repo = RDF::DataObjects::Repository.new('sqlite3:test.db')
# repo = RDF::DataObjects::Repository.new 'postgres://postgres@server/database'
# heroku_repo = RDF::DataObjects::Repository.new(ENV['DATABASE_URL'])
repo.load('http://datagraph.org/jhacker/foaf.nt')

# How many statements did we have?
repo.count
#=> 10

# Get the URI of the first subject
jhacker = repo.first.subject
#=> #<RDF::URI(http://datagraph.org/jhacker/foaf)>

# Delete everything to do with it
jhacker_statements = repo.query(:subject => jhacker) 
repo.delete *jhacker_statements
repo.count
#=> 7

# with Postgres, we could have done this, but SQLite gives us a locking error:
# repo.delete(*repo.query(:subject => jhacker))

# Changed our mind--bring it back
repo.insert *jhacker_statements
repo.count
#=> 10

Contributing

This repository uses Git Flow to mange development and release activity. All submissions must be on a feature branch based on the develop branch to ease staging and integration.

  • Do your best to adhere to the existing coding conventions and idioms.
  • Don't use hard tabs, and don't leave trailing whitespace on any line.
  • Do document every method you add using YARD annotations. Read the tutorial or just look at the existing code for examples.
  • Don't touch the .gemspec, VERSION or AUTHORS files. If you need to change them, do so on your private branch only.
  • Do feel free to add yourself to the CREDITS file and the corresponding list in the the README. Alphabetical order applies.
  • Do note that in order for us to merge any non-trivial changes (as a rule of thumb, additions larger than about 15 lines of code), we need an explicit public domain dedication on record from you.

Support

The preferred method to report issues is the issue queue at http://github.com/ruby-rdf/rdf-do/issues. You'll get the the most attention if you submit a failing test for a bug, or a pending test for a feature.

We'd also like to hear from you on the mailing list: http://lists.w3.org/Archives/Public/public-rdf-ruby

Miscellany