Class: OpenURL::ContextObject

Inherits:
Object
  • Object
show all
Includes:
EnsureValidEncoding
Defined in:
lib/openurl/context_object.rb

Overview

The ContextObject class is intended to both create new OpenURL 1.0 context objects or parse existing ones, either from Key-Encoded Values (KEVs) or XML.

Create a new ContextObject programmatically 

require 'openurl/context_object'
include OpenURL

ctx = ContextObject.new
ctx.referent.set_format('journal') # important to do this FIRST.

ctx.referent.add_identifier('info:doi/10.1016/j.ipm.2005.03.024')
ctx.referent.set_metadata('issn', '0306-4573')
ctx.referent.set_metadata('aulast', 'Bollen')
ctx.referrer.add_identifier('info:sid/google')
puts ctx.kev
# url_ver=Z39.88-2004&ctx_tim=2007-10-29T12%3A18%3A53-0400&ctx_ver=Z39.88-2004&ctx_enc=info%3Aofi%2Fenc%3AUTF-8&ctx_id=&rft.issn=0306-4573&rft.aulast=Bollen&rft_val_fmt=info%3Aofi%2Ffmt%3Axml%3Axsd%3Ajournal&rft_id=info%3Adoi%2F10.1016%2Fj.ipm.2005.03.024&rfr_id=info%3Asid%2Fgoogle

Create a new ContextObject from an existing kev or XML serialization:

ContextObject.new_from_kev( kev_context_object ) ContextObject.new_from_xml( xml_context_object ) # Can be String or REXML::Document

Serialize a ContextObject to kev or XML :

ctx.kev ctx.xml

Constant Summary collapse

@@defined_entities = 
{"rft"=>"referent", "rfr"=>"referrer", "rfe"=>"referring-entity", "req"=>"requestor", "svc"=>"service-type", "res"=>"resolver"}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ContextObject

Creates a new ContextObject object and initializes the ContextObjectEntities.



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# File 'lib/openurl/context_object.rb', line 49

def initialize()       
  @referent = ContextObjectEntity.new
  @referrer = ContextObjectEntity.new
  @referringEntity = ContextObjectEntity.new
  @requestor = ContextObjectEntity.new
  @serviceType = []
  @resolver = []
  @foreign_keys = {}
  @openurl_ver = "Z39.88-2004"
  @admin = {"ctx_ver"=>{"label"=>"version", "value"=>@openurl_ver}, "ctx_tim"=>{"label"=>"timestamp", "value"=>DateTime.now().to_s}, "ctx_id"=>{"label"=>"identifier", "value"=>""}, "ctx_enc"=>{"label"=>"encoding", "value"=>"info:ofi/enc:UTF-8"}}    
end

Instance Attribute Details

#admin ⇒ Object (readonly)

Returns the value of attribute admin.



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# File 'lib/openurl/context_object.rb', line 41

def admin
  @admin
end

#foreign_keys ⇒ Object

Returns the value of attribute foreign_keys.



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# File 'lib/openurl/context_object.rb', line 43

def foreign_keys
  @foreign_keys
end

#openurl_ver ⇒ Object

Returns the value of attribute openurl_ver.



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# File 'lib/openurl/context_object.rb', line 43

def openurl_ver
  @openurl_ver
end

#referent ⇒ Object

Returns the value of attribute referent.



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# File 'lib/openurl/context_object.rb', line 41

def referent
  @referent
end

#referrer ⇒ Object

Returns the value of attribute referrer.



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# File 'lib/openurl/context_object.rb', line 41

def referrer
  @referrer
end

#referringEntity ⇒ Object

Returns the value of attribute referringEntity.



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# File 'lib/openurl/context_object.rb', line 41

def referringEntity
  @referringEntity
end

#requestor ⇒ Object

Returns the value of attribute requestor.



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# File 'lib/openurl/context_object.rb', line 41

def requestor
  @requestor
end

#resolver ⇒ Object (readonly)

Returns the value of attribute resolver.



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# File 'lib/openurl/context_object.rb', line 41

def resolver
  @resolver
end

#serviceType ⇒ Object (readonly)

Returns the value of attribute serviceType.



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# File 'lib/openurl/context_object.rb', line 41

def serviceType
  @serviceType
end

Class Method Details

.entities(term) ⇒ Object 



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# File 'lib/openurl/context_object.rb', line 479

def self.entities(term)
  return @@defined_entities[term] if @@defined_entities.keys.index(term)
  return @@defined_entities[@@defined_entities.values.index(term)] if @@defined_entities.values.index(term)
  return nil
  
end

.new_from_context_object(context_object) ⇒ Object

Initialize a new ContextObject object from an existing OpenURL::ContextObject



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# File 'lib/openurl/context_object.rb', line 510

def self.new_from_context_object(context_object)
  co = self.new
  co.import_context_object(context_object)
  return co
end

.new_from_form_vars(params) ⇒ Object

Initialize a new ContextObject object from a CGI.params style hash Expects a hash with default value being nil though, not [] as CGI.params actually returns, beware. Can also accept a Rails-style params hash (single string values, not array values), although this may lose some context object information.



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# File 'lib/openurl/context_object.rb', line 210

def self.new_from_form_vars(params)
  co = self.new
  if ctx_val = (params[:url_ctx_val]||params["url_ctx_val"]) and not ctx_val.empty? # this is where the context object stuff will be
    co.admin.keys.each do | adm |
      if params[adm.to_s]
        if params[adm.to_s].is_a?(Array)
          co.set_administration_key(adm, params[adm.to_s].first) 
        else
          co.set_administration_key(adm, params[adm.to_s]) 
        end
      end
    end
    
    if ctx_format = (params["url_ctx_fmt"]||params[:url_ctx_fmt])
      ctx_format = ctx_format.first if ctx_format.is_a?(Array)
      ctx_val = ctx_val.first if ctx_val.is_a?(Array)        
      if ctx_format  == "info:ofi/fmt:xml:xsd:ctx"
        co.import_xml(ctx_val)
      elsif ctx_format == "info:ofi/fmt:kev:mtx:ctx"
        co.import_kev(ctx_val)
      end
    end  
  else # we'll assume this is standard inline kev
    co.import_hash(params)
  end
  return co
end

.new_from_hash(hash) ⇒ Object

Initialize a new ContextObject object from an existing key/value hash



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# File 'lib/openurl/context_object.rb', line 435

def self.new_from_hash(hash)      
  co = self.new
  co.import_hash(hash)
  return co
end

.new_from_kev(kev) ⇒ Object

Initialize a new ContextObject object from an existing KEV



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# File 'lib/openurl/context_object.rb', line 199

def self.new_from_kev(kev)
  co = self.new
  co.import_kev(kev)
  return co
end

.new_from_xml(xml) ⇒ Object

Initialize a new ContextObject object from an existing XML ContextObject



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# File 'lib/openurl/context_object.rb', line 276

def self.new_from_xml(xml)
  co = self.new
  co.import_xml(xml)
  return co
end

Instance Method Details

#clean_char_encoding!(hash) ⇒ Object

Takes a hash of openurl key/values, as output by CGI.parse from a query string for example (values can be strings or arrays of string). Mutates hash in place.

Force encodes to UTF8 or 8859-1, depending on ctx_enc presence and value.

Replaces any illegal bytes with replacement chars, transcodes to UTF-8 if needed to ensure UTF8 on way out.



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# File 'lib/openurl/context_object.rb', line 292

def clean_char_encoding!(hash)
  # Bail if we're not in ruby 1.9
  return unless "".respond_to? :encoding
  
  source_encoding = "UTF-8"
  if hash["ctx_enc"] == "info:ofi/enc:ISO-8859-1"
    hash.delete("ctx_enc")
    source_encoding = "ISO-8859-1"      
  end
  
  hash.each_pair do |key, values|
    # get a list of all terminal values, whether wrapped
    # in arrays or not. We're going to mutate them. 
    [values].flatten.compact.each do | v |
        v.force_encoding(source_encoding)
        if source_encoding == "UTF-8"
          ensure_valid_encoding!(v, :invalid => :replace )
        else
          # transcode, replacing any bad chars. 
          v.encode!("UTF-8", :invalid => :replace, :undef => :replace )
        end
    end
  end
  
end

#coins(classnames = nil, innerHTML = nil) ⇒ Object

Outputs a COinS (ContextObject in SPANS) span tag for the ContextObject. Arguments are any other CSS classes you want included and the innerHTML content.



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# File 'lib/openurl/context_object.rb', line 167

def coins (classnames=nil, innerHTML=nil)      
  return "<span class='Z3988 #{classnames}' title='"+CGI.escapeHTML(self.kev(true))+"'>#{innerHTML}</span>"
end

#deep_copy ⇒ Object 



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# File 'lib/openurl/context_object.rb', line 70

def deep_copy
  cloned = ContextObject.new
  cloned.import_context_object( self )
  return cloned
end

#get_entity_obj(abbr) ⇒ Object

Takes a string abbreviated entity (‘rfr’, ‘rft’, etc.), returns the appropriate ContextObjectEntity object for this ContextObject, in some cases lazily creating and assigning it. @@defined_entities = “rfr”=>“referrer”, “rfe”=>“referring-entity”, “req”=>“requestor”, “svc”=>“service-type”, “res”=>“resolver”



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# File 'lib/openurl/context_object.rb', line 459

def get_entity_obj(abbr)
  ivar_name = @@defined_entities[abbr]

  return nil unless ivar_name

  return case ivar_name
    when "service-type"        
      @serviceType << ContextObjectEntity.new if @serviceType.empty?
      @serviceType.first
    when "resolver"
      @resolver << ContextObjectEntity.new if @resolver.empty?
      @resolver.first
    when "referring-entity"
      instance_variable_get("@referringEntity")
    else
      instance_variable_get("@#{ivar_name}")
    end
end

#import_context_object(context_object) ⇒ Object

Imports an existing OpenURL::ContextObject object and sets the appropriate entity values.



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# File 'lib/openurl/context_object.rb', line 489

def import_context_object(context_object)
  @admin.each_key { |k|
    self.set_administration_key(k, context_object.admin[k]["value"])
  }	
  ["@referent", "@referringEntity", "@requestor", "@referrer"].each do | ent |
    self.instance_variable_set(ent.to_sym, Marshal::load(Marshal.dump(context_object.instance_variable_get(ent.to_sym))))
  end
  context_object.serviceType.each { |svc|        
    @serviceType << Marshal::load(Marshal.dump(svc))          
  }
  context_object.resolver.each { |res|
    @resolver << Marshal::load(Marshal.dump(res))                  
  }      
  context_object.foreign_keys.each do | key, val |
    self.foreign_keys[key] = val
  end
end

#import_hash(hash) ⇒ Object

Imports an existing hash of ContextObject values and sets the appropriate entities.



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# File 'lib/openurl/context_object.rb', line 320

def import_hash(hash)    
  clean_char_encoding!(hash) 
  
  ref = {}
  {"@referent"=>"rft", "@referrer"=>"rfr", "@referringEntity"=>"rfe",
    "@requestor"=>"req"}.each do | ent, abbr |
    next unless hash["#{abbr}_val_fmt"]    
    val = hash["#{abbr}_val_fmt"]
    val = val[0] if val.is_a?(Array)
    self.instance_variable_set(ent.to_sym, ContextObjectEntityFactory.format(val))
  end
  
  {"@serviceType"=>"svc","@resolver"=>"res"}.each do | ent, abbr |
    next unless hash["#{abbr}_val_fmt"]
    val = hash["#{abbr}_val_fmt"]
    val = val[0] if val.is_a?(Array)        
    self.instance_variable_set(ent.to_sym, [ContextObjectEntityFactory.format(val)])
  end  

  openurl_keys = ["url_ver", "url_tim", "url_ctx_fmt"]
  hash.each do |key, value|      
    val = value
    val = value[0] if value.is_a?(Array)

    next if value.nil? || value.empty?
    
    if openurl_keys.include?(key)          
      next # None of these matter much for our purposes
    elsif @admin.has_key?(key)          
      self.set_administration_key(key, val) 
    elsif key.match(/^[a-z]{3}_val_fmt/)        
      next
    elsif key.match(/^[a-z]{3}_ref/)
      # determines if we have a by-reference context object
      (entity, v, fmt) = key.split("_")
      ent = self.get_entity_obj(entity)
      unless ent
        self.foreign_keys[key] = val
        next
      end
      # by-reference requires two fields, format and location, if this is
      # the first field we've run across, set a place holder until we get
      # the other value          
      unless ref[entity]
        if fmt
          ref_key = "format"
        else 
          ref_key = "location"
        end
        ref[entity] = [ref_key, val]
      else
        if ref[entity][0] == "format"              
          instance_variable_get("@#{ent}").set_reference(val, ref[entity][1])
        else
          instance_variable_get("@#{ent}").set_reference(ref[entity][1], val)
        end
      end
    elsif key.match(/^[a-z]{3}_id$/)
      # Get the entity identifier
      (entity, v) = key.split("_")
      ent = self.get_entity_obj(entity)
      unless ent
        self.foreign_keys[key] = val
        next
      end
      # May or may not be an array, turn it into one.
      [value].flatten.each do | id |
        ent.add_identifier(id)
      end
              
    elsif key.match(/^[a-z]{3}_dat$/)
      # Get any private data          
      (entity, v) = key.split("_")
      ent = self.get_entity_obj(entity)
      unless ent
        self.foreign_keys[key] = val
        next
      end          
      ent.set_private_data(val)  
    else
      # collect the entity metadata
      keyparts = key.split(".")            
      if keyparts.length > 1
        # This is 1.0 OpenURL
        ent = self.get_entity_obj(keyparts[0])
        unless ent
          self.foreign_keys[key] = val
          next
        end            
        ent.set_metadata(keyparts[1], val)
      else
        # This is a 0.1 OpenURL.  Your mileage may vary on how accurately
        # this maps.
        if key == 'id'
          if value.is_a?(Array)
            value.each do | id |
              @referent.add_identifier(id)
            end
          else
            @referent.add_identifier(val)
          end              
        elsif key == 'sid'
          @referrer.set_identifier("info:sid/"+val.to_s) 
        elsif key == 'pid'
          @referent.set_private_data(val.to_s)           
        else 
          @referent.set_metadata(key, val)
        end
      end
    end
  end  
  

  
  # Initialize a new ContextObject object from an existing key/value hash
  def self.new_from_hash(hash)      
    co = self.new
    co.import_hash(hash)
    return co
  end
  
  # if we don't have a referent format (most likely because we have a 0.1
  # OpenURL), try to determine something from the genre.  If that doesn't 
  # exist, just call it a journal since most 0.1 OpenURLs would be one,
  # anyway.
  unless @referent.format        
    fmt = case @referent.metadata['genre']
    when /article|journal|issue|proceeding|conference|preprint/ then 'journal'
    when /book|bookitem|report|document/ then 'book'
    else 'journal'
    end
    @referent.set_format(fmt)
  end
end

#import_kev(kev) ⇒ Object

Imports an existing Key-encoded value string and sets the appropriate entities.



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# File 'lib/openurl/context_object.rb', line 182

def import_kev(kev)      
  co = CGI::parse(kev)
  co2 = {}
  co.each do |key, val|
    if val.is_a?(Array)
      if val.length == 1
        co2[key] = val[0]
      else
        co2[key] = val
      end        
    end      	
  end
  self.import_hash(co2)
end

#import_xml(xml) ⇒ Object

Imports an existing XML encoded context object and sets the appropriate entities



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# File 'lib/openurl/context_object.rb', line 241

def import_xml(xml)			
  if xml.is_a?(String)        
    xml.force_encoding("UTF-8") if xml.respond_to? :force_encoding
    ensure_valid_encoding!(xml, :invalid => :replace)
    doc = REXML::Document.new xml.gsub(/>[\s\t]*\n*[\s\t]*</, '><').strip
  elsif xml.is_a?(REXML::Document)
    doc = xml
  else
    raise ArgumentError, "Argument must be an REXML::Document or well-formed XML string"
  end
  
  # Cut to the context object
  ctx = REXML::XPath.first(doc, ".//ctx:context-object", {"ctx"=>"info:ofi/fmt:xml:xsd:ctx"})



  

  
  ctx.attributes.each do |attr, val|				
    @admin.each do |adm, vals|
      self.set_administration_key(adm, val) if vals["label"] == attr											
    end
  end
  ctx.to_a.each do | ent |
    if @@defined_entities.value?(ent.name())
      self.import_entity(ent)
    else
      self.import_custom_node(ent)
    end
  end
end

#kev(no_date = false) ⇒ Object

Output the ContextObject as a Key-encoded value string. Pass a boolean true argument if you do not want the ctx_tim key included.



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# File 'lib/openurl/context_object.rb', line 114

def kev(no_date=false)
  kevs = ["url_ver=#{self.openurl_ver}", "url_ctx_fmt=#{CGI.escape("info:ofi/fmt:kev:mtx:ctx")}"]
  
  # Loop through the administrative metadata      
  @admin.each_key do |k|
    next if k == "ctx_tim" && no_date                    
    kevs.push(k+"="+CGI.escape(@admin[k]["value"].to_s)) if @admin[k]["value"]                  
  end

  {@referent=>"rft", @referringEntity=>"rfe", @requestor=>"req", @referrer=>"rfr"}.each do | ent, abbr |
    kevs.push(ent.kev(abbr)) unless ent.empty?                  
  end
  
  {@serviceType=>"svc", @resolver=>"res"}.each do |entCont, abbr|        
    entCont.each do |ent|
      next if ent.empty?          
      kevs.push(ent.kev(abbr))
    end
  end        
  return kevs.join("&")
end

#set_administration_key(key, val) ⇒ Object

Sets a ContextObject administration field.

Raises:

  • (ArgumentException) 


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# File 'lib/openurl/context_object.rb', line 174

def set_administration_key(key, val)
  raise ArgumentException, "#{key} is not a valid admin key!" unless @admin.keys.index(key)
  @admin[key]["value"] = val
end

#to_hash ⇒ Object

Outputs the ContextObject as a ruby hash—hash version of the kev format. Outputting a context object as a hash is imperfect, because context objects can have multiple elements with the same key–and because some keys depend on SAP1 vs SAP2. So this function is really deprecated, but here because we have so much code dependent on it.



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# File 'lib/openurl/context_object.rb', line 142

def to_hash            
  co_hash = {"url_ver"=>self.openurl_ver, "url_ctx_fmt"=>"info:ofi/fmt:kev:mtx:ctx"}           
  
  @admin.each_key do |k|
    co_hash[k]=@admin[k]["value"] if @admin[k]["value"]
  end

  {@referent=>"rft", @referringEntity=>"rfe", @requestor=>"req", @referrer=>"rfr"}.each do | ent, abbr |
    co_hash.merge!(ent.to_hash(abbr)) unless ent.empty?
  end

  # svc  and res are arrays of ContextObjectEntity
  {@serviceType=>"svc", @resolver=>"res"}.each do |ent_list, abbr|        
    ent_list.each do |ent|
      co_hash.merge!(ent.to_hash(abbr)) unless ent.empty?
    end
  end        
  return co_hash
end

#xml ⇒ Object

Serialize the ContextObject to XML.



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# File 'lib/openurl/context_object.rb', line 78

def xml      
  doc = REXML::Document.new()
  coContainer = doc.add_element "ctx:context-objects"
  coContainer.add_namespace("ctx","info:ofi/fmt:xml:xsd:ctx")
  coContainer.add_namespace("xsi", "http://www.w3.org/2001/XMLSchema-instance")
  coContainer.add_attribute("xsi:schemaLocation", "info:ofi/fmt:xml:xsd:ctx http://www.openurl.info/registry/docs/info:ofi/fmt:xml:xsd:ctx")
  co = coContainer.add_element "ctx:context-object"
  @admin.each_key do |k|
    next if k == "ctx_enc"
    co.add_attribute(@admin[k]["label"], @admin[k]["value"])
  end

  [{@referent=>"rft"}, 
    {@referringEntity=>"rfe"}, {@requestor=>"req"},        
    {@referrer=>"rfr"}].each do | entity |
    
    entity.each do | ent, label |
      ent.xml(co, label) unless ent.empty?
    end
  end
  
  [{@serviceType=>"svc"}, {@resolver=>"res"}].each do |entity|
    entity.each do | entCont, label |        
      entCont.each do |ent|
        ent.xml(co, label) unless ent.empty?                      
      end
    end
  end

  return doc.to_s
end