Class: Triannon::LdpWriter

Inherits:
Object
  • Object
show all
Defined in:
app/services/triannon/ldp_writer.rb

Overview

writes data/objects to the LDP server; also does deletes

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(anno, id = nil) ⇒ LdpWriter

Returns a new instance of LdpWriter.

Parameters:

  • anno (Triannon::Annotation) —

    a Triannon::Annotation object

  • id (String) (defaults to: nil) —

    the unique id for the LDP container for the passed annotation; defaults to nil



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# File 'app/services/triannon/ldp_writer.rb', line 131

def initialize(anno, id = nil)
  @anno = anno
  @id = id
  base_url = Triannon.config[:ldp]['url'].strip
  base_url.chop! if base_url.end_with?('/')
  container_path = Triannon.config[:ldp]['uber_container']
  if container_path
    container_path.strip!
    container_path = container_path[1..-1] if container_path.start_with?('/')
    container_path.chop! if container_path.end_with?('/')
  end
  @base_uri = "#{base_url}/#{container_path}"
end

Class Method Details

.container_exist?(path) ⇒ Boolean

Returns true if container already exists; false otherwise.

Parameters:

  • path (String) —

    the path part of the container url, after the ldp base url

Returns:

  • (Boolean) —

    true if container already exists; false otherwise



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# File 'app/services/triannon/ldp_writer.rb', line 52

def self.container_exist? path
  base_url = Triannon.config[:ldp]['url'].strip
  path.strip!
  separator = (base_url.end_with?('/') || path.start_with?('/')) ? "" : '/'
  conn = Faraday.new url: base_url + separator + path
  resp = conn.head
  if resp.status.between?(400, 600)
    false
  else
    true
  end
end

.create_anno(anno) ⇒ Object

use LDP protocol to create the OpenAnnotation.Annotation in an RDF store

Parameters:



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# File 'app/services/triannon/ldp_writer.rb', line 9

def self.create_anno(anno)
  if anno && anno.graph
    # TODO:  special case if the Annotation object already has an id --
    #  see https://github.com/sul-dlss/triannon/issues/84
    ldp_writer = Triannon::LdpWriter.new anno
    id = ldp_writer.create_base

    bodies_solns = anno.graph.query([nil, RDF::Vocab::OA.hasBody, nil])
    if bodies_solns.size > 0
      ldp_writer.create_body_container
      ldp_writer.create_body_resources
    end

    targets_solns = anno.graph.query([nil, RDF::Vocab::OA.hasTarget, nil])
    # NOTE:  Annotation is invalid if there are no target statements
    if targets_solns.size > 0
      ldp_writer.create_target_container
      ldp_writer.create_target_resources
    end

    id
  end
end

.create_basic_container(parent_path, slug) ⇒ Boolean

Creates an empty LDP BasicContainer in LDP Storage

Parameters:

  • parent_path (String) —

    the path part, after the ldp base url – in essence, the LDP BasicContainer that will be the parent of the to-be-created BasicContainer.

  • slug (String) —

    the value to send in Http Header ‘Slug’ – this is appended to the parent container’s path to become the id of the newly created BasicContainer

Returns:

  • (Boolean) —

    true if the container was created; false otherwise



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# File 'app/services/triannon/ldp_writer.rb', line 73

def self.create_basic_container parent_path, slug
  if slug.blank?
    puts "create_basic_container called with nil or empty slug, parent_path '#{parent_path}'"
    return false
  end
  base_url = Triannon.config[:ldp]['url'].strip
  base_url.chop! if base_url.end_with?('/')
  slug.strip!
  slug = slug[1..-1] if slug.start_with?('/')
  if parent_path
    parent_path.strip!
    parent_path = parent_path[1..-1] if parent_path.start_with?('/')
    parent_path.chop! if parent_path.end_with?('/')
  end

  full_path = (parent_path ? parent_path + '/' : "") + slug
  full_url = base_url + '/' + full_path

  if container_exist? full_path
    puts "Container #{full_url} already exists."
    false
  else
    g = RDF::Graph.new
    null_rel_uri = RDF::URI.new
    g << [null_rel_uri, RDF.type, RDF::Vocab::LDP.BasicContainer]
    conn = Faraday.new url: base_url + (parent_path ? '/' + parent_path : "")
    resp = conn.post do |req|
      # Note from Fcrepo docs:
      #  https://wiki.duraspace.org/display/FEDORA41/RESTful+HTTP+API+-+Containers#RESTfulHTTPAPI-Containers-BluePOSTCreatenewresourceswithinaLDPcontainer
      #   "If the MIME type corresponds to a supported RDF format or SPARQL-Update, the uploaded content will be
      #   parsed as RDF and used to populate the child node properties.  RDF will be interpreted using the current
      #   resource as the base URI (e.g. <> will be expanded to the current URI)."
      # Thus, the next line is needed even if the body of this POST is empty
      req.headers['Content-Type'] = 'text/turtle'
      req.headers['Slug'] = slug
      req.body = g.to_ttl
    end

    if resp.status == 201
      new_url = resp.headers['Location'] ? resp.headers['Location'] : resp.headers['location']
      if new_url == full_url
        puts "Created Basic Container #{new_url}"
        true
      else
        puts "Created Basic Container #{new_url} instead of #{full_url}"
        false
      end
    else
      puts "Unable to create Basic Container #{full_url}:  LDP Storage response status #{resp.status}; body #{resp.body}"
      false
    end
  end
end

.delete_container(id) ⇒ Object Also known as: delete_anno

deletes the indicated container and all its child containers from the LDP

store

Parameters:

  • id (String) —

    the unique id for the LDP container for an annotation. May be a compound id, such as uuid1/t/uuid2, in which case the LDP container object uuid2 and its children are deleted from the LDP store, but LDP containers uuid1/t and uuid1 are not deleted from the LDP store.



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# File 'app/services/triannon/ldp_writer.rb', line 40

def self.delete_container id
  if id && id.size > 0
    ldpw = Triannon::LdpWriter.new nil
    ldpw.delete_containers id
  end
end

Instance Method Details

#create_base ⇒ String

creates a stored LDP container for this object’s Annotation, without its

targets or bodies (as those are put in descendant containers)
SIDE EFFECT:  assigns the uuid of the container created to @id

Returns:

  • (String) —

    the unique id for the LDP container created for this annotation



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# File 'app/services/triannon/ldp_writer.rb', line 150

def create_base
  if @anno.graph.query([nil, RDF::Triannon.externalReference, nil]).count > 0
    fail Triannon::ExternalReferenceError, "Incoming annotations may not have http://triannon.stanford.edu/ns/externalReference as a predicate."
  end

  if @anno.graph.id_as_url && @anno.graph.id_as_url.size > 0
    fail Triannon::ExternalReferenceError, "Incoming new annotations may not have an existing id (yet)."
  end

  # TODO:  special case if the Annotation object already has an id --
  #  see https://github.com/sul-dlss/triannon/issues/84

  # we need to work with a copy of the graph so we don't change @anno.graph
  g = RDF::Graph.new
  @anno.graph.each { |s|
    g << s
  }
  g = OA::Graph.new(g)
  g.remove_non_base_statements
  g.make_null_relative_uri_out_of_blank_node

  @id = create_resource g.to_ttl
end

#create_body_container ⇒ Object

creates the LDP container for any and all bodies for this annotation



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# File 'app/services/triannon/ldp_writer.rb', line 175

def create_body_container
  create_direct_container RDF::Vocab::OA.hasBody
end

#create_body_resources ⇒ Object

create the body resources inside the (already created) body container



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# File 'app/services/triannon/ldp_writer.rb', line 185

def create_body_resources
  create_resources_in_container RDF::Vocab::OA.hasBody
end

#create_target_container ⇒ Object

creates the LDP container for any and all targets for this annotation



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# File 'app/services/triannon/ldp_writer.rb', line 180

def create_target_container
  create_direct_container RDF::Vocab::OA.hasTarget
end

#create_target_resources ⇒ Object

create the target resources inside the (already created) target container



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# File 'app/services/triannon/ldp_writer.rb', line 190

def create_target_resources
  create_resources_in_container RDF::Vocab::OA.hasTarget
end

#delete_containers(ldp_container_uris) ⇒ Object

Returns true if a resource was deleted; false otherwise.

Parameters:

  • ldp_container_uris (Array<String>) —

    an Array of ids for LDP containers. (can also be a String) e.g. [@base_uri/(uuid1)/t/(uuid2), @base_uri/(uuid1)/t/(uuid3)] or [@base_uri/(uuid)] or (uuid)

Returns:

  • true if a resource was deleted; false otherwise



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# File 'app/services/triannon/ldp_writer.rb', line 198

def delete_containers ldp_container_uris
  return false if !ldp_container_uris || ldp_container_uris.empty?
  if ldp_container_uris.kind_of? String
    ldp_container_uris = [ldp_container_uris]
  end
  something_deleted = false
  ldp_container_uris.each { |uri|
    ldp_id = uri.to_s.split(@base_uri + '/').last
    resp = conn.delete { |req| req.url ldp_id }
    if resp.status != 204
      fail Triannon::LDPStorageError.new("Unable to delete LDP container #{ldp_id}", resp.status, resp.body)
    end
    something_deleted = true
  }
  something_deleted
end