Class: JSON::LD::Resource

Inherits:
Object
  • Object
show all
Defined in:
lib/json/ld/resource.rb

Overview

Simple Ruby reflector class to provide native access to JSON-LD objects

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(node_definition, options = {}) ⇒ Resource

A new resource from the parsed graph

Parameters:

  • node_definition (Hash{String => Object})
  • options (Hash{Symbol => Object}) (defaults to: {})

Options Hash (options):

  • :context (String) —

    Resource context, used for finding appropriate collection and JSON-LD context.

  • :clean (Boolean) — default: false
  • :compact (Boolean) — default: false —

    Assume ‘node_definition` is in expanded form and compact using `context`.

  • :reconciled (Boolean) — default: !new —

    node_definition is not based on Mongo IDs and must be reconciled against Mongo, or merged into another resource.

  • :new (Boolean) — default: true —

    This is a new resource, not yet saved to Mongo

  • :stub (Boolean) — default: false —

    This is a stand-in for another resource that has not yet been retrieved (or created) from Mongo



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# File 'lib/json/ld/resource.rb', line 81

def initialize(node_definition, options = {})
  @context_name = options[:context]
  @context = self.class.set_context(@context_name)
  @clean = options.fetch(:clean, false)
  @new = options.fetch(:new, true)
  @reconciled = options.fetch(:reconciled, !@new)
  @resolved = false
  @attributes = if options[:compact]
    JSON::LD::API.compact(node_definition, @context)
  else
    node_definition
  end
  @id = @attributes['@id']
  @anon = @id.nil? || @id.to_s[0,2] == '_:'
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method, *args) ⇒ Object

Access individual fields, from subject definition



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# File 'lib/json/ld/resource.rb', line 231

def method_missing(method, *args)
  property(method.to_s)
end

Instance Attribute Details

#attributes ⇒ Object (readonly)

Object representation of resource



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# File 'lib/json/ld/resource.rb', line 8

def attributes
  @attributes
end

#context ⇒ Object (readonly)

Context associated with this resource



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# File 'lib/json/ld/resource.rb', line 18

def context
  @context
end

#id ⇒ Object (readonly)

ID of this resource



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# File 'lib/json/ld/resource.rb', line 13

def id
  @id
end

Class Method Details

.set_context(ctx) ⇒ JSON::LD::EvaluationContext

Manage contexts used by resources.

Parameters:

  • ctx (String)

Returns:



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# File 'lib/json/ld/resource.rb', line 58

def self.set_context(ctx)
  (@@contexts ||= {})[ctx] = JSON::LD::EvaluationContext.new.parse(ctx)
end

Instance Method Details

#anonymous? ⇒ Boolean

Anonymous resources have BNode ids or no schema:url

Returns:

  • (Boolean) 


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# File 'lib/json/ld/resource.rb', line 44

def anonymous?; @anon; end

#clean? ⇒ Boolean

Is this resource clean (i.e., saved to mongo?)

Returns:

  • (Boolean) 


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# File 'lib/json/ld/resource.rb', line 23

def clean?; @clean; end

#deresolve ⇒ Hash

Reverse resolution of resource attributes. Just returns ‘attributes` if resource is unresolved. Otherwise, replaces `Resource` values with node references.

Result is expanded and re-compacted to get to normalized representation.

Returns:

  • (Hash) —

    deresolved attribute hash



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# File 'lib/json/ld/resource.rb', line 112

def deresolve
  node_definition = if resolved?
    deresolved = attributes.keys.inject({}) do |memo, prop|
      value = attributes[prop]
      memo[prop] = case value
      when Resource
        {'id' => value.id}
      when Array
        value.map do |v|
          v.is_a?(Resource) ? {'id' => v.id} : v
        end
      else
        value
      end
      memo
    end
    deresolved
  else
    attributes
  end

  compacted = nil
  JSON::LD::API.expand(node_definition, @context) do |expanded|
    compacted = JSON::LD::API.compact(expanded, @context)
  end
  compacted.delete_if {|k, v| k == '@context'}
end

#dirty? ⇒ Boolean

Is this resource dirty (i.e., not yet saved to mongo?)

Returns:

  • (Boolean) 


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# File 'lib/json/ld/resource.rb', line 28

def dirty?; !clean?; end

#hash ⇒ Fixnum

Return a hash of this object, suitable for use by for ETag

Returns:

  • (Fixnum) 


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# File 'lib/json/ld/resource.rb', line 99

def hash
  self.deresolve.hash
end

#inspect ⇒ Object 



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# File 'lib/json/ld/resource.rb', line 235

def inspect
  "<Resource" +
  attributes.map do |k, v|
    "\n  #{k}: #{v.inspect}"
  end.join(" ") +
  ">"
end

#merge(resource) ⇒ Resource

Merge resources FIXME: If unreconciled or unresolved resources are merged against reconciled/resolved resources, they will appear to not match, even if they are really the same thing.

Parameters:

Returns:



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# File 'lib/json/ld/resource.rb', line 199

def merge(resource)
  if attributes.neq?(resource.attributes)
    resource.attributes.each do |p, v|
      next if p == 'id'
      if v.nil? or (v.is_a?(Array) and v.empty?)
        attributes.delete(p)
      else
        attributes[p] = v
      end
    end
    @resolved = @clean = false
  end
  self
end

#new? ⇒ Boolean

Is this a new resource, which has not yet been synched or created within the DB?

Returns:

  • (Boolean) 


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# File 'lib/json/ld/resource.rb', line 52

def new?; !!@new; end

#property(prop_name) ⇒ Object

Access individual fields, from subject definition



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# File 'lib/json/ld/resource.rb', line 228

def property(prop_name); @attributes.fetch(prop_name, nil); end

#reconciled? ⇒ Boolean

Has this resource been reconciled against a mongo ID?

Returns:

  • (Boolean) 


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# File 'lib/json/ld/resource.rb', line 33

def reconciled?; @reconciled; end

#resolve(reference_map) ⇒ Resource

Update node references using the provided map. This replaces node references with Resources, either stub or instantiated.

Node references with ids not in the reference_map will cause stub resources to be added to the map.

Parameters:

Returns:



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# File 'lib/json/ld/resource.rb', line 158

def resolve(reference_map)
  return if resolved?
  def update_obj(obj, reference_map)
    case obj
    when Array
      obj.map {|o| update_obj(o, reference_map)}
    when Hash
      if obj.node_ref?
        reference_map[obj['id']] ||= Resource.new(obj,
          :context => @context_name,
          :clean => false,
          :stub => true
          )
      else
        obj.keys.each do |k|
          obj[k] = update_obj(obj[k], reference_map)
        end
        obj
      end
    else
      obj
    end
  end

  #$logger.debug "resolve(0): #{attributes.inspect}"
  @attributes.each do |k, v|
    next if %w(id type).include?(k)
    @attributes[k] = update_obj(@attributes[k], reference_map)
  end
  #$logger.debug "resolve(1): #{attributes.inspect}"
  @resolved = true
  self
end

#resolved? ⇒ Boolean

Has this resource been resolved so that all references are to other Resources?

Returns:

  • (Boolean) 


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# File 'lib/json/ld/resource.rb', line 39

def resolved?; @resolved; end

#save ⇒ Boolean

Override this method to implement save using an appropriate storage mechanism.

Save the object to the Mongo collection use Upsert to create things that don’t exist. First makes sure that the resource is valid.

Returns:

  • (Boolean) —

    true or false if resource not saved

Raises:

  • (NotImplemented) 


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# File 'lib/json/ld/resource.rb', line 223

def save
  raise NotImplemented
end

#stub? ⇒ Boolean

Is this a stub resource, which has not yet been synched or created within the DB?

Returns:

  • (Boolean) 


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# File 'lib/json/ld/resource.rb', line 48

def stub?; !!@stub; end

#to_json(options = nil) ⇒ String

Serialize to JSON-LD, minus ‘@context` using a deresolved version of the attributes

Parameters:

  • options (Hash) (defaults to: nil)

Returns:

  • (String) —

    serizlied JSON representation of resource



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# File 'lib/json/ld/resource.rb', line 145

def to_json(options = nil)
  deresolve.to_json(options)
end

#update_obj(obj, reference_map) ⇒ Object 



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# File 'lib/json/ld/resource.rb', line 160

def update_obj(obj, reference_map)
  case obj
  when Array
    obj.map {|o| update_obj(o, reference_map)}
  when Hash
    if obj.node_ref?
      reference_map[obj['id']] ||= Resource.new(obj,
        :context => @context_name,
        :clean => false,
        :stub => true
        )
    else
      obj.keys.each do |k|
        obj[k] = update_obj(obj[k], reference_map)
      end
      obj
    end
  else
    obj
  end
end