Module: FedoraLens::Lenses

Included in:
TestClass
Defined in:
lib/fedora_lens/lenses.rb

Class Method Summary collapse

Class Method Details

.as_dom ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 87

def as_dom
  Lens[
    # TODO figure out a memoizing strategy so we don't parse multiple times
    get: lambda {|xml| Nokogiri::XML(xml)},
    put: lambda {|xml, value| value.to_xml},
    create: lambda {|value| value.to_xml}
  ]
end

.at_css(selector) ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 96

def at_css(selector)
  Lens[
    get: lambda {|doc| doc.at_css(selector).content},
    put: lambda {|doc, value| 
    doc.at_css(selector).content = value; doc},
    # can't do a css create because we don't know the structure
  ]
end

.compose(outer, inner) ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 185

def compose(outer, inner)
  Lens[
    get: lambda do |source|
      inner.get(outer.get(source))
    end,
    put: lambda do |source, value|
      outer.put(source, inner.put(outer.get(source), value))
    end
  ]
end

.empty_property(graph, rdf_subject, predicate, should_delete) ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 105

def empty_property(graph, rdf_subject, predicate, should_delete)
  if should_delete
    graph.query([rdf_subject, predicate, nil]).each_statement do |statement|
      if should_delete.call(statement.object)
        graph.delete(statement)
      end
    end
  else
    graph.delete([rdf_subject, predicate, nil])
  end
end

.get_predicate(predicate, opts = {}) ⇒ Object

Parameters:

  • predicate (RDF::URI)
  • opts (Hash) (defaults to: {})

Options Hash (opts):

  • :select (Proc) —

    a proc that takes the object and returns true if it should be included in this subset of the predicates. Used for storing different classes of objects under different attribute names even though they all use the same predicate.



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# File 'lib/fedora_lens/lenses.rb', line 125

def get_predicate(predicate, opts = {})
  Lens[
    get: lambda do |orm|
      values = orm.value(predicate)
      if opts[:select]
        values.select { |val| opts[:select].call(val) }
      else
        values
      end
    end,
    put: lambda do |orm, values|
      empty_property(orm.graph, orm.resource.subject_uri, predicate, opts[:select])
      Array(values).each do |value|
        next if value.nil?
        orm.graph.insert([orm.resource.subject_uri, predicate, value])
      end
      orm
    end,
    create: lambda do |values|
      orm = Ldp::Orm.new(Ldp::Resource::RdfSource.new(FedoraLens.connection, '', RDF::Graph.new))
      values.each do |value|
        orm.graph.insert([orm.resource.subject_uri, predicate, value])
      end
      orm
    end
  ]
end

.hash_update ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 64

def hash_update
  Lens[
    get: lambda {|hash| hash[key]},
    put: lambda {|hash, pair| hash.merge(pair[0] => pair[1])}
  ]
end

.literal_to_string ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 24

def literal_to_string
  Lens[
    get: :to_s.to_proc,
    put: lambda do |source, value|
      if source.is_a?(RDF::Literal)
        RDF::Literal.new(value, language: source.language, datatype: source.datatype)
      else
        RDF::Literal.new(value)
      end
    end
  ]
end

.literals_to_strings ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 37

def literals_to_strings
  Lens[
    get: lambda do |source|
      source.map(&:to_s)
    end,
    put: lambda do |sources, values|
      Array(values).map do |value|
        RDF::Literal.new(value)
      end
    end
  ]
end

.load_model(klass) ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 153

def load_model(klass)
  Lens[
    get: lambda do |id|
      klass.find(id)
    end,
    put: lambda do |id, model|
      model.save
      id
    end
  ]
end

.load_or_build_orm ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 165

def load_or_build_orm
  Lens[
    get: lambda do |uri|
      if uri.present?
        Ldp::Orm.new(Ldp::Resource::RdfSource.new(FedoraLens.connection, uri.to_s))
      else
        Ldp::Orm.new(Ldp::Resource::RdfSource.new(FedoraLens.connection, nil, RDF::Graph.new))
      end
    end,
    put: lambda do |uri, orm|
      if orm.resource.subject.present?
        orm.save
      else
        orm.resource.create
      end
      orm.resource.subject_uri
    end
  ]
end

.orm_to_hash(name_to_lens) ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 71

def orm_to_hash(name_to_lens)
  Lens[
    get: lambda do |orm|
      name_to_lens.inject({}) do |hash, (key, lens)|
        hash.merge(key => lens.get(orm))
      end
    end,
    put: lambda do |orm, hash|
      name_to_lens.each do |(key, lens)|
        lens.put(orm, hash[key])
      end
      orm
    end
  ]
end

.single ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 16

def single
  Lens[
    get: :first.to_proc,
    put: lambda {|source, value| source[0] = value; source},
    create: lambda {|value| [value]}
  ]
end

.uris_to_ids(&block) ⇒ Object

Parameters:

  • class_lambda (Proc) —

    returns an object which implements uri_to_id and id_to_uri



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# File 'lib/fedora_lens/lenses.rb', line 51

def uris_to_ids(&block)
  Lens[
    get: lambda do |source|
      source.map { |uri| yield.uri_to_id(URI.parse(uri).to_s) }
    end,
    put: lambda do |sources, values|
      Array(values).compact.map do |value|
        RDF::URI.new(yield.id_to_uri(value))
      end
    end
  ]
end

.zip(first, second) ⇒ Object 



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# File 'lib/fedora_lens/lenses.rb', line 196

def zip(first, second)
end