Module: Ladder::Resource::ClassMethods

Defined in:
lib/ladder/resource.rb

Instance Method Summary collapse

Instance Method Details

#new_from_graph(graph, objects = {}, pattern = nil) ⇒ Ladder::Resource?

Create a new instance of this class, populated with values and related objects from a given RDF::Graph for this model.

By default, the graph will be traversed starting with the first node that matches the same RDF.type as this class; however, an optional RDF::Queryable pattern can be provided, @see RDF::Queryable#query

As nodes are traversed in the graph, the instantiated objects will be added to a Hash that is passed recursively, in order to prevent infinite traversal in the case of cyclic graphs.

Parameters:

  • graph (RDF::Graph) —

    an RDF::Graph to traverse

  • objects (Hash) (defaults to: {}) —

    a keyed Hash of already-created objects in the graph

  • pattern (RDF::Query, RDF::Statement, Array(RDF::Term), Hash) (defaults to: nil) —

    a query pattern

Returns:



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# File 'lib/ladder/resource.rb', line 189

def new_from_graph(graph, objects = {}, pattern = nil)
  # Default to getting the first object in the graph with the same RDF type as this class
  pattern ||= [nil, RDF.type, resource_class.type]

  root_subject = graph.query(pattern).first_subject
  return unless root_subject

  # If the subject is an existing model, just retrieve it
  new_object = Ladder::Resource.from_uri(root_subject) if root_subject.is_a? RDF::URI
  new_object ||= new

  # Add object to stack for recursion
  objects[root_subject] = new_object

  graph.query([root_subject]).each_statement do |statement|
    next if objects[statement.object]

    # TODO: If the object is a list, process members individually
    # list = RDF::List.new statement.object, graph
    # binding.pry unless list.empty?

    # If the object is a BNode, dereference the relation
    if statement.object.is_a? RDF::Node
      klass = new_object.klass_from_predicate(statement.predicate)
      next unless klass

      object = klass.new_from_graph(graph, objects)
      next unless object

      objects[statement.object] = object
      new_object.send(:<<, statement) { object }
    else
      new_object << statement
    end
  end # end each_statement

  new_object
end

#property(field_name, opts = {}) ⇒ ActiveTriples::Resource

Define a Mongoid field/relation on the class as well as an RDF property on the delegated resource

Parameters:

  • field_name (String) —

    ActiveModel attribute name for the field

  • opts (Hash) (defaults to: {}) —

    options to pass to Mongoid / ActiveTriples

Returns:

  • (ActiveTriples::Resource) —

    a modified resource

See Also:

  • ActiveTriples::Resource#property
  • ActiveTriples::Properties


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# File 'lib/ladder/resource.rb', line 159

def property(field_name, opts = {})
  if opts[:class_name]
    mongoid_opts = { autosave: true, index: true }.merge(opts.except(:predicate, :multivalue))
    has_and_belongs_to_many(field_name, mongoid_opts) unless relations.keys.include? field_name.to_s
  else
    mongoid_opts = { localize: true }.merge(opts.except(:predicate, :multivalue))
    field(field_name, mongoid_opts) unless fields[field_name.to_s]
  end

  opts.except!(*mongoid_opts.keys)

  super
end