Class: JSON::LD::API

Inherits:
Object
  • Object
show all
Includes:
Compact, Expand, Flatten, Frame, FromRDF, ToRDF
Defined in:
lib/json/ld/api.rb

Overview

A JSON-LD processor implementing the JsonLdProcessor interface.

This API provides a clean mechanism that enables developers to convert JSON-LD data into a a variety of output formats that are easier to work with in various programming languages. If a JSON-LD API is provided in a programming environment, the entirety of the following API must be implemented.

See Also:

Author:

Constant Summary collapse

OPEN_OPTS =

Options used for open_file

{
  :headers => %w(Accept: application/ld+json, application/json)
}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Frame

#cleanup_preserve, #frame, #remove_dependents

Methods included from Utils

#blank_node?, #index?, #list?, #node?, #node_reference?, #value?

Methods included from FromRDF

#from_statements

Methods included from Flatten

#generate_node_map

Methods included from ToRDF

#add_quad, #node, #parse_list, #statements

Methods included from Compact

#compact

Methods included from Expand

#expand

Constructor Details

#initialize(input, context, options = {}) {|api| ... } ⇒ API

Initialize the API, reading in any document and setting global options

Parameters:

  • input (String, #read, Hash, Array)
  • context (String, #read, , Hash, Array, JSON::LD::EvaluationContext) —

    An external context to use additionally to the context embedded in input when expanding the input.

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

Options Hash (options):

  • :base (Boolean) —

    The Base IRI to use when expanding the document. This overrides the value of ‘input` if it is a IRI. If not specified and `input` is not an IRI, the base IRI defaults to the current document IRI if in a browser context, or the empty string if there is no document context.

  • :compactArrays (Boolean) — default: true —

    If set to ‘true`, the JSON-LD processor replaces arrays with just one element with that element during compaction. If set to `false`, all arrays will remain arrays even if they have just one element.

  • :conformanceCallback (Proc) —

    The purpose of this option is to instruct the processor about whether or not it should continue processing. If the value is null, the processor should ignore any key-value pair associated with any recoverable conformance issue and continue processing. More details about this feature can be found in the ConformanceCallback section.

  • :flatten (Boolean, String, RDF::URI) —

    If set to a value that is not ‘false`, the JSON-LD processor must modify the output of the Compaction Algorithm or the Expansion Algorithm by coalescing all properties associated with each subject via the Flattening Algorithm. The value of `flatten must` be either an IRI value representing the name of the graph to flatten, or `true`. If the value is `true`, then the first graph encountered in the input document is selected and flattened.

  • :optimize (Boolean) — default: false —

    If set to ‘true`, the JSON-LD processor is allowed to optimize the output of the Compaction Algorithm to produce even compacter representations. The algorithm for compaction optimization is beyond the scope of this specification and thus not defined. Consequently, different implementations MAY implement different optimization algorithms. (Presently, this is a noop).

  • :useNativeTypes (Boolean) — default: true —

    If set to ‘true`, the JSON-LD processor will use native datatypes for expression xsd:integer, xsd:boolean, and xsd:double values, otherwise, it will use the expanded form.

  • :useRdfType (Boolean) — default: false —

    If set to ‘true`, the JSON-LD processor will try to convert datatyped literals to JSON native types instead of using the expanded object form when converting from RDF. `xsd:boolean` values will be converted to `true` or `false`. `xsd:integer` and `xsd:double` values will be converted to JSON numbers.

  • :rename_bnodes (Boolean) — default: true —

    Rename bnodes as part of expansion, or keep them the same.

Yields:

  • (api)

Yield Parameters:



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# File 'lib/json/ld/api.rb', line 73

def initialize(input, context, options = {}, &block)
  @options = {:compactArrays => true}.merge(options)
  options = {:rename_bnodes => true}.merge(options)
  @namer = options[:rename_bnodes] ? BlankNodeNamer.new("t") : BlankNodeMapper.new
  @value = case input
  when Array, Hash then input.dup
  when IO, StringIO then JSON.parse(input.read)
  when String
    content = nil
    @options = {:base => input}.merge(@options)
    RDF::Util::File.open_file(input, OPEN_OPTS) {|f| content = JSON.parse(f.read)}
    content
  end
  @context = EvaluationContext.new(@options)
  @context = @context.parse(context) if context
  
  if block_given?
    case block.arity
      when 0, -1 then instance_eval(&block)
      else block.call(self)
    end
  end
end

Instance Attribute Details

#context ⇒ JSON::LD::EvaluationContext

Input evaluation context

Returns:



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# File 'lib/json/ld/api.rb', line 40

def context
  @context
end

#input ⇒ String, ...

Current input

Returns:



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# File 'lib/json/ld/api.rb', line 35

attr_accessor :value

#namer ⇒ JSON::LD::BlankNodeNamer (readonly)

Current Blank Node Namer

Returns:



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# File 'lib/json/ld/api.rb', line 45

def namer
  @namer
end

#value ⇒ String, ...

Current input

Returns:



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# File 'lib/json/ld/api.rb', line 35

def value
  @value
end

Class Method Details

.compact(input, context, callback = nil, options = {}) {|jsonld| ... } ⇒ Hash

Compacts the given input according to the steps in the Compaction Algorithm. The input must be copied, compacted and returned if there are no errors. If the compaction fails, an appropirate exception must be thrown.

If no context is provided, the input document is compacted using the top-level context of the document

The resulting ‘Hash` is returned via the provided callback.

Note that for Ruby, if the callback is not provided and a block is given, it will be yielded

Parameters:

  • input (String, #read, Hash, Array) —

    The JSON-LD object to copy and perform the compaction upon.

  • context (String, #read, Hash, Array, JSON::LD::EvaluationContext) —

    The base context to use when compacting the input.

  • callback (Proc) (defaults to: nil) —

    (&block) Alternative to using block, with same parameters.

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

    See options in #initialize Other options passed to expand

Yields:

  • jsonld

Yield Parameters:

  • jsonld (Hash) —

    The compacted JSON-LD document

Returns:

  • (Hash) —

    The compacted JSON-LD document

Raises:

See Also:



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# File 'lib/json/ld/api.rb', line 163

def self.compact(input, context, callback = nil, options = {})
  expanded = result = nil

  # 1) Perform the Expansion Algorithm on the JSON-LD input.
  #    This removes any existing context to allow the given context to be cleanly applied.
  expanded = API.expand(input, nil, nil, options.merge(:debug => nil))

  API.new(expanded, context, options) do
    debug(".compact") {"expanded input: #{expanded.to_json(JSON_STATE)}"}
    result = compact(value, nil)

    # xxx) Add the given context to the output
    result = case result
    when Hash then self.context.serialize.merge(result)
    when Array
      kwgraph = self.context.compact_iri('@graph', :quiet => true)
      self.context.serialize.merge(kwgraph => result)
    when String
      kwid = self.context.compact_iri('@id', :quiet => true)
      self.context.serialize.merge(kwid => result)
    end
  end
  callback.call(result) if callback
  yield result if block_given?
  result
end

.expand(input, context = nil, callback = nil, options = {}) {|jsonld| ... } ⇒ Array<Hash>

Expands the given input according to the steps in the Expansion Algorithm. The input must be copied, expanded and returned if there are no errors. If the expansion fails, an appropriate exception must be thrown.

The resulting ‘Array` is returned via the provided callback.

Note that for Ruby, if the callback is not provided and a block is given, it will be yielded

Parameters:

  • input (String, #read, Hash, Array) —

    The JSON-LD object to copy and perform the expansion upon.

  • context (String, #read, Hash, Array, JSON::LD::EvaluationContext) (defaults to: nil) —

    An external context to use additionally to the context embedded in input when expanding the input.

  • callback (Proc) (defaults to: nil) —

    (&block) Alternative to using block, with same parameters.

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

    See options in #initialize

Yields:

  • jsonld

Yield Parameters:

  • jsonld (Array<Hash>) —

    The expanded JSON-LD document

Returns:

  • (Array<Hash>) —

    The expanded JSON-LD document

Raises:

See Also:



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# File 'lib/json/ld/api.rb', line 120

def self.expand(input, context = nil, callback = nil, options = {})
  result = nil
  API.new(input, context, options) do |api|
    result = api.expand(api.value, nil, api.context)
  end

  # If, after the algorithm outlined above is run, the resulting element is an
  # JSON object with just a @graph property, element is set to the value of @graph's value.
  result = result['@graph'] if result.is_a?(Hash) && result.keys == %w(@graph)

  # Finally, if element is a JSON object, it is wrapped into an array.
  result = [result].compact unless result.is_a?(Array)
  callback.call(result) if callback
  yield result if block_given?
  result
end

.flatten(input, graph, context, callback = nil, options = {}) {|jsonld| ... } ⇒ Array<Hash>

Flattens the given input according to the steps in the Flattening Algorithm. The input must be flattened and returned if there are no errors. If the flattening fails, an appropriate exception must be thrown.

The resulting ‘Array` is returned via the provided callback.

Note that for Ruby, if the callback is not provided and a block is given, it will be yielded. If there is no block, the value will be returned.

Parameters:

  • input (String, #read, Hash, Array) —

    The JSON-LD object or array of JSON-LD objects to flatten or an IRI referencing the JSON-LD document to flatten.

  • graph (String, RDF::URI) —

    The graph in the document that should be flattened. To return the default graph @default has to be passed, for the merged graph @merged and for any other graph the IRI identifying the graph has to be passed. The default value is @merged.

  • context (String, #read, Hash, Array, JSON::LD::EvaluationContext) —

    An optional external context to use additionally to the context embedded in input when expanding the input.

  • callback (Proc) (defaults to: nil) —

    (&block) Alternative to using block, with same parameters.

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

    See options in #initialize Other options passed to expand

Yields:

  • jsonld

Yield Parameters:

  • jsonld (Hash) —

    The framed JSON-LD document

Returns:

  • (Array<Hash>) —

    The framed JSON-LD document

Raises:

See Also:



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# File 'lib/json/ld/api.rb', line 215

def self.flatten(input, graph, context, callback = nil, options = {})
  result = nil
  graph ||= '@merged'

  # Expand input to simplify processing
  expanded_input = API.expand(input)

  # Initialize input using frame as context
  API.new(expanded_input, nil, options) do
    debug(".flatten") {"expanded input: #{value.to_json(JSON_STATE)}"}

    # Generate _nodeMap_
    node_map = Hash.ordered
    self.generate_node_map(value, node_map, (graph.to_s == '@merged' ? '@merged' : '@default'))
    
    result = []

    # If nodeMap has no property graph, return result, otherwise set definitions to its value.
    definitions = node_map.fetch(graph.to_s, {})
    
    # Foreach property and value of definitions
    definitions.keys.sort.each do |prop|
      value = definitions[prop]
      result << value
    end
    
    result
  end

  callback.call(result) if callback
  yield result if block_given?
  result
end

.frame(input, frame, callback = nil, options = {}) {|jsonld| ... } ⇒ Array<Hash>

Frames the given input using the frame according to the steps in the Framing Algorithm. The input is used to build the framed output and is returned if there are no errors. If there are no matches for the frame, null must be returned. Exceptions must be thrown if there are errors.

The resulting ‘Array` is returned via the provided callback.

Note that for Ruby, if the callback is not provided and a block is given, it will be yielded

Parameters:

  • input (String, #read, Hash, Array) —

    The JSON-LD object to copy and perform the framing on.

  • frame (String, #read, Hash, Array) —

    The frame to use when re-arranging the data.

  • callback (Proc) (defaults to: nil) —

    (&block) Alternative to using block, with same parameters.

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

    See options in #initialize Other options passed to expand

Options Hash (options):

  • :embed (Boolean) — default: true —

    a flag specifying that objects should be directly embedded in the output, instead of being referred to by their IRI.

  • :explicit (Boolean) — default: false —

    a flag specifying that for properties to be included in the output, they must be explicitly declared in the framing context.

  • :omitDefault (Boolean) — default: false —

    a flag specifying that properties that are missing from the JSON-LD input should be omitted from the output.

Yields:

  • jsonld

Yield Parameters:

  • jsonld (Hash) —

    The framed JSON-LD document

Returns:

  • (Array<Hash>) —

    The framed JSON-LD document

Raises:

See Also:



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# File 'lib/json/ld/api.rb', line 283

def self.frame(input, frame, callback = nil, options = {})
  result = nil
  match_limit = 0
  framing_state = {
    :embed       => true,
    :explicit    => false,
    :omitDefault => false,
    :embeds      => nil,
  }
  framing_state[:embed] = options[:embed] if options.has_key?(:embed)
  framing_state[:explicit] = options[:explicit] if options.has_key?(:explicit)
  framing_state[:omitDefault] = options[:omitDefault] if options.has_key?(:omitDefault)

  # de-reference frame to create the framing object
  frame = case frame
  when Hash then frame.dup
  when IO, StringIO then JSON.parse(frame.read)
  when String
    content = nil
    RDF::Util::File.open_file(frame, OPEN_OPTS) {|f| content = JSON.parse(f.read)}
    content
  end

  # Expand frame to simplify processing
  expanded_frame = API.expand(frame)
  
  # Expand input to simplify processing
  expanded_input = API.expand(input)

  # Initialize input using frame as context
  API.new(expanded_input, nil, options) do
    #debug(".frame") {"context from frame: #{context.inspect}"}
    #debug(".frame") {"expanded frame: #{expanded_frame.to_json(JSON_STATE)}"}
    #debug(".frame") {"expanded input: #{value.to_json(JSON_STATE)}"}

    # Get framing nodes from expanded input, replacing Blank Node identifiers as necessary
    all_nodes = Hash.ordered
    depth do
      generate_node_map(value, all_nodes, '@merged')
    end
    @node_map = all_nodes['@merged']
    debug(".frame") {"node_map: #{@node_map.to_json(JSON_STATE)}"}

    result = []
    frame(framing_state, @node_map, expanded_frame[0], result, nil)
    debug(".frame") {"after frame: #{result.to_json(JSON_STATE)}"}
    
    # Initalize context from frame
    @context = depth {@context.parse(frame['@context'])}
    # Compact result
    compacted = depth {compact(result, nil)}
    compacted = [compacted] unless compacted.is_a?(Array)

    # Add the given context to the output
    kwgraph = context.compact_iri('@graph', :quiet => true)
    result = context.serialize.merge({kwgraph => compacted})
    debug(".frame") {"after compact: #{result.to_json(JSON_STATE)}"}
    result = cleanup_preserve(result)
  end

  callback.call(result) if callback
  yield result if block_given?
  result
end

.fromRDF(input, callback = nil, options = {}) {|jsonld| ... } ⇒ Array<Hash>

Take an ordered list of RDF::Statements and turn them into a JSON-LD document.

The resulting ‘Array` is returned via the provided callback.

Note that for Ruby, if the callback is not provided and a block is given, it will be yielded

Parameters:

  • input (Array<RDF::Statement>)
  • callback (Proc) (defaults to: nil) —

    (&block) Alternative to using block, with same parameteres.

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

    See options in #initialize

Yields:

  • jsonld

Yield Parameters:

  • jsonld (Hash) —

    The JSON-LD document in expanded form

Returns:

  • (Array<Hash>) —

    The JSON-LD document in expanded form



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# File 'lib/json/ld/api.rb', line 404

def self.fromRDF(input, callback = nil, options = {}, &block)
  options = {:useNativeTypes => true}.merge(options)
  result = nil

  API.new(nil, nil, options) do |api|
    result = api.from_statements(input)
  end

  callback ||= block if block_given?
  callback.call(result) if callback
  result
end

.toRDF(input, context = nil, callback = nil, options = {}) {|statement| ... } ⇒ Array<RDF::Statement>

Processes the input according to the RDF Conversion Algorithm, calling the provided callback for each triple generated.

Note that for Ruby, if the callback is not provided and a block is given, it will be yielded

Parameters:

  • input (String, #read, Hash, Array) —

    The JSON-LD object to process when outputting statements.

  • context (String, #read, Hash, Array, JSON::LD::EvaluationContext) (defaults to: nil) —

    An external context to use additionally to the context embedded in input when expanding the input.

  • callback (Proc) (defaults to: nil) —

    (&block) Alternative to using block, with same parameteres.

  • options ({Symbol,String => Object}) (defaults to: {}) —

    See options in #initialize Options passed to expand

Yields:

  • statement

Yield Parameters:

  • statement (RDF::Statement)

Returns:

  • (Array<RDF::Statement>) —

    if no block given

Raises:



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# File 'lib/json/ld/api.rb', line 366

def self.toRDF(input, context = nil, callback = nil, options = {}, &block)
  results = []
  API.new(input, context, options) do |api|
    # 1) Perform the Expansion Algorithm on the JSON-LD input.
    #    This removes any existing context to allow the given context to be cleanly applied.
    result = api.expand(api.value, nil, api.context)

    api.send(:debug, ".expand") {"expanded input: #{result.to_json(JSON_STATE)}"}
    # Start generating statements
    api.statements("", result, nil, nil, nil) do |statement|
      callback ||= block if block_given?
      if callback
        callback.call(statement)
      else
        results << statement
      end
    end
  end
  results
end