Class: Blacklight

Inherits:
Service show all
Includes:
MarcHelper, MetadataHelper, UmlautHttp, XmlSchemaHelper
Defined in:
app/service_adaptors/blacklight.rb

Overview

Searches a Blacklight with the cql extension installed.

Params include:

base_url

required. Complete URL to catalog.atom action. Eg “blacklight.mse.jhu.edu/catalog.atom

bl_fields

required with at least some entries if you want this to do anything. Describe the names of given semantic fields in your BL instance.

  • issn

  • isbn

  • lccn

  • oclcnum

  • id (defaults to 'id')

  • title

  • author

  • serials_limit_clause => not an index name, full URL clause for a limit to apply to known serials searches, for instance “f[]=Serial”

identifier_search

Do catalog search on issn/isbn/oclcnum/lccn/bibId. Default true.

keyword_search

Do catalog search on title/author keywords where applicable. Generally only used when identifier_search finds no hits, if identifier_search is on. Default true.

keyword_per_page

How many records to fetch from blacklight when doing keyword searches.

exclude_holdings

Can be used to exclude certain 'dummy' holdings that have certain collection, location, or other values. Eg: exclude_holdings:

collection_str:
  - World Wide Web
  - Internet
rft_id_bibnum_prefixes

Array of URI prefixes in an rft_id that indicate that the actual solr id comes next. For instance, if your blacklight will send “blacklight.com/catalog/some_id” in an rft_id, then include “blacklight.com/catalog/”. Optional.

Constant Summary

Constants inherited from Service

Service::LinkOutFilterTask, Service::StandardTask

Instance Attribute Summary collapse

Attributes inherited from Service

#group, #name, #priority, #request, #service_id, #status, #task, #url

Instance Method Summary collapse

Methods included from XmlSchemaHelper

xml_ns, #xml_ns, #xml_to_holdings

Methods included from MarcHelper

#add_856_links, #edition_statement, #get_title, #get_years, #gmd_values, #service_type_for_856, #should_skip_856_link?, #strip_gmd

Methods included from MetadataHelper

#get_doi, #get_epage, #get_gpo_item_nums, #get_identifier, #get_isbn, #get_issn, #get_lccn, #get_month, #get_oclcnum, #get_pmid, #get_search_creator, #get_search_terms, #get_search_title, #get_spage, #get_sudoc, #get_top_level_creator, #get_year, #normalize_lccn, #normalize_title, #raw_search_title, title_is_serial?

Methods included from UmlautHttp

#http_fetch, #proxy_like_headers

Methods inherited from Service

#credits, #display_name, #handle_wrapper, #link_out_filter, #preempted_by, required_config_params, #response_url, #translate

Constructor Details

#initialize(config) ⇒ Blacklight


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# File 'app/service_adaptors/blacklight.rb', line 46

def initialize(config)
  # defaults    
  # If you are sending an OpenURL from a library service, you may
  # have the HIP bibnum, and include it in the OpenURL as, eg.
  # rft_id=http://catalog.library.jhu.edu/bib/343434 (except URL-encoded)
  # Then you'd set rft_id_bibnum_prefix to http://catalog.library.jhu.edu/bib/
  @rft_id_bibnum_prefixes = []
  @cql_search_field = "cql"
  @keyword_per_page = 10
  @identifier_search = true
  @keyword_search = true
  @link_to_search = true
  super(config)
  @bl_fields = { "id" => "id "}.merge(@bl_fields)
end

Instance Attribute Details

#base_urlObject (readonly)

Returns the value of attribute base_url


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# File 'app/service_adaptors/blacklight.rb', line 38

def base_url
  @base_url
end

#bl_fieldsObject (readonly)

Returns the value of attribute bl_fields


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# File 'app/service_adaptors/blacklight.rb', line 39

def bl_fields
  @bl_fields
end

#cql_search_fieldObject (readonly)

Returns the value of attribute cql_search_field


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# File 'app/service_adaptors/blacklight.rb', line 38

def cql_search_field
  @cql_search_field
end

#issnObject (readonly)

Returns the value of attribute issn


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# File 'app/service_adaptors/blacklight.rb', line 39

def issn
  @issn
end

Instance Method Details

#add_holdings(holdings_url, options = {}) ⇒ Object

Takes a url that will return atom response of dlf_expanded content. Adds Umlaut “holding” ServiceResponses for dlf_expanded, as appropriate. Returns number of holdings added.


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# File 'app/service_adaptors/blacklight.rb', line 249

def add_holdings(holdings_url, options = {})
  options[:match_reliability] ||= ServiceResponse::MatchExact
  options[:marc_data] ||= {}
  
  atom = Nokogiri::XML( http_fetch(holdings_url).body )
  content_entries = atom.search("/atom:feed/atom:entry/atom:content", xml_ns)
  
  # For each atom entry, find the dlf_expanded record. For each dlf_expanded
  # record, take all of it's holdingsrec's if it has them, or all of it's
  # items if it doesn't, and add them to list. We wind up with a list
  # of mixed holdingsrec's and items. 
  holdings_xml = content_entries.collect do |dlf_expanded|      
    copies = dlf_expanded.xpath("dlf:record/dlf:holdings/dlf:holdingset/dlf:holdingsrec", xml_ns)
    copies.length > 0 ? copies : dlf_expanded.xpath("dlf:record/dlf:items/dlf:item", xml_ns)
  end.flatten
  
  service_data = holdings_xml.collect do |  |
    atom_entry = .at_xpath("ancestor::atom:entry", xml_ns)
    atom_id = atom_entry.at_xpath("atom:id/text()", xml_ns).to_s

    edition_str = edition_statement(options[:marc_data][atom_id])
    url = atom_entry.at_xpath("atom:link[@rel='alternate'][@type='text/html']/attribute::href", xml_ns).to_s
    
    xml_to_holdings(  ).merge(
      :service => self,
      :match_reliability => options[:match_reliability],
      :edition_str => edition_str,
      :url => url
    )
  end
  
  # strip out holdings that aren't really holdings
  service_data.delete_if do |data|
    @exclude_holdings.collect do |key, values|
      values.include?(data[key.to_sym])
    end.include?(true)
  end

  # Sort by "collection"
  service_data.sort do |a, b|
    a[:collection_str] <=> b[:collection_str]
  end
  
  service_data.each do |data|
    request.add_service_response(data.merge(:service => self, :service_type_value =>"holding"))
  end

  return service_data.length
end

#bib_ids_from_atom_entries(entries) ⇒ Object


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# File 'app/service_adaptors/blacklight.rb', line 332

def bib_ids_from_atom_entries(entries)
  entries.xpath("atom:id/text()", xml_ns).to_a.collect do |atom_id|
        atom_id.to_s =~ /([^\/]+)$/
        $1
  end.compact
end

#blacklight_keyword_search_url(request, options = {}) ⇒ Object

Construct a CQL search against blacklight for author and title, possibly with serial limit. Ask for Atom with embedded MARC back.


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# File 'app/service_adaptors/blacklight.rb', line 193

def blacklight_keyword_search_url(request, options = {})
  options[:format] ||= "atom"
  options[:content_format] ||= "marc"
  
  clauses = []

  # We need both title and author to search keyword style, or
  # we get too many false positives. Except serials we'll do
  # title only. sigh, logic tree. 
  
  # Also need to use appropriate 'container' title if avail, not
  # article title. 
   = request.referent.
  title = ['jtitle']     
  title = ['btitle'] if title.blank?
  title = ['title'] if title.blank?
  # remove sub-title for better search
  title.gsub!(/\:.*\Z/, '') if title

  author = get_top_level_creator(request.referent)
  return nil unless title && (author || (@bl_fields["serials_limit_clause"] && title_is_serial?(request.referent)))
  # phrase search for title, just raw dismax for author
  # Embed quotes inside the quoted value, need to backslash-quote for CQL,
  # and backslash the backslashes for ruby literal. 
  clauses.push("#{@bl_fields["title"]} = \"\\\"#{escape_for_cql_double_quotes title}\\\"\"")    
  clauses.push("#{@bl_fields["author"]} = \"#{escape_for_cql_double_quotes author}\"") if author
  
  url = base_url + "?search_field=#{@cql_search_field}&content_format=#{options[:content_format]}&q=#{CGI.escape(clauses.join(" AND "))}"

  if (@bl_fields["serials_limit_clause"] &&
      title_is_serial?(request.referent))        
    url += "&" + @bl_fields["serials_limit_clause"]
  end
  
  return url
end

#blacklight_precise_search_url(request, format = "marc") ⇒ Object

Send a CQL request for any identifiers present. Ask for for an atom response with embedded marc21 back.


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# File 'app/service_adaptors/blacklight.rb', line 158

def blacklight_precise_search_url(request, format = "marc")

  # Add search clauses for our identifiers, if we have them and have a configured search field for them. 
  clauses = []
  added = []
  ["lccn", "isbn", "oclcnum"].each do |key|
    if bl_fields[key] && request.referent.send(key)
      clauses.push( "#{bl_fields[key]} = \"#{request.referent.send(key)}\"")
      added << key
    end
  end
  # Only add ISSN if we don't have an ISBN, reduces false matches
  if ( !added.include?("isbn") &&
       bl_fields["issn"] && 
       request.referent.issn)
     clauses.push("#{bl_fields["issn"]} = \"#{request.referent.issn}\"")
  end
    
  
  # Add Solr document identifier if we can get one from the URL
  
  if (id = get_solr_id(request.referent))
    clauses.push("#{bl_fields['id']} = \"#{id}\"")
  end
  
  # if we have nothing, we can do no search.
  return nil if clauses.length == 0
  
  cql = clauses.join(" OR ")
  
  return base_url + "?search_field=#{@cql_search_field}&content_format=#{format}&q=#{CGI.escape(cql)}"             
end

#blacklight_url_for_ids(ids, format = "dlf_expanded") ⇒ Object


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# File 'app/service_adaptors/blacklight.rb', line 339

def blacklight_url_for_ids(ids, format="dlf_expanded")
  return nil unless ids.length > 0  

  return base_url + "?search_field=#{@cql_search_field}&content_format=#{format}&q=" + CGI.escape("#{@bl_fields["id"]} any \"#{ids.join(" ")}\"")
end

#escape_for_cql_double_quotes(str) ⇒ Object


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# File 'app/service_adaptors/blacklight.rb', line 238

def escape_for_cql_double_quotes(str)
  str = str.gsub('"', " ")
  str = str.gsub("'", "''")

  return str
end

#filter_keyword_entries(request, atom_entries, options = {}) ⇒ Object


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# File 'app/service_adaptors/blacklight.rb', line 299

def filter_keyword_entries(request, atom_entries, options = {})
  options[:exclude_ids] ||= []
  options[:remove_subtitle] ||= true
  
  title = request.referent['jtitle']     
  title = request.referent['btitle'] if title.blank?
  title = request.referent['title'] if title.blank?
  
  request_title_forms = [
      title.downcase,        
      normalize_title( title )
  ]
  request_title_forms << normalize_title( title, :remove_subtitle => true) if options[:remove_subtitle]
  request_title_forms = request_title_forms.compact.uniq

  # Only keep entries with title match, and that aren't in the
  # exclude_ids list. 
  good_entries = atom_entries.find_all do |atom_entry|
    title = atom_entry.xpath("atom:title/text()", xml_ns).text  
 
    entry_title_forms = [
      title.downcase,
      normalize_title(title)
    ]
    entry_title_forms << normalize_title(title, :remove_subtitle=>true) if options[:remove_subtitle]
    entry_title_forms = entry_title_forms.compact.uniq
    
    ((entry_title_forms & request_title_forms).length > 0 &&
     (bib_ids_from_atom_entries(atom_entry) & options[:exclude_ids]).length == 0)
  end
  return Nokogiri::XML::NodeSet.new( atom_entries.document, good_entries)
end

#get_solr_id(rft) ⇒ Object


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# File 'app/service_adaptors/blacklight.rb', line 346

def get_solr_id(rft)
  rft.identifiers.each do |id|
    @rft_id_bibnum_prefixes.each do |prefix|
      if id[0, prefix.length] == prefix
        return id[prefix.length, id.length]
      end
    end
  end

  return nil    
end

#handle(request) ⇒ Object


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# File 'app/service_adaptors/blacklight.rb', line 70

def handle(request)
  ids_processed = []
  holdings_added = 0
  
  if (@identifier_search && url = blacklight_precise_search_url(request) )
    doc = Nokogiri::XML( http_fetch(url).body )
    
    ids_processed.concat( bib_ids_from_atom_entries( doc.xpath("atom:feed/atom:entry", xml_ns) ) )

    # namespaces make xpath harder than it should be, but css
    # selector still easy, thanks nokogiri! Grab the marc from our
    # results. 
    marc_matches = doc.xpath("atom:feed/atom:entry/atom:content[@type='application/marc']", xml_ns).collect do |encoded_marc21|
      MARC::Reader.decode( Base64.decode64(encoded_marc21.text).force_encoding("UTF-8") )        
    end

    add_856_links(request, marc_matches )

    # Got to make a second fetch for dlf_expanded info, cause BL doens't
    # (yet) let us ask for more than one at once
    holdings_url = blacklight_precise_search_url( request, "dlf_expanded" )
    holdings_added += add_holdings( holdings_url ) if holdings_url
  end

  #keyword search.    
  if (@keyword_search &&
      url = blacklight_keyword_search_url(request))
          
      doc = Nokogiri::XML( http_fetch(url).body )
      # filter out matches whose titles don't really match at all, or
      # which have already been seen in identifier search. 
      entries = filter_keyword_entries(request, doc.xpath("atom:feed/atom:entry", xml_ns) , :exclude_ids => ids_processed, :remove_subtitle => (! title_is_serial?(request.referent)) )
      
      
      marc_by_atom_id = {}
      
      # Grab the marc from our entries. Important not to do a // xpath
      # search, or we'll wind up matching parent elements not actually
      # included in our 'entries' list. 
      marc_matches = entries.xpath("atom:content[@type='application/marc']", xml_ns).collect do |encoded_marc21|
        marc = MARC::Reader.decode( Base64.decode64(encoded_marc21.text).force_encoding("UTF-8") )

        marc_by_atom_id[ encoded_marc21.at_xpath("ancestor::atom:entry/atom:id/text()", xml_ns).to_s  ] = marc
        
        marc
      end
     
      # We've filtered out those we consider just plain bad
      # matches, everything else we're going to call
      # an approximate match. Sort so that those with
      # a date close to our request date are first.
      if ( year = get_year(request.referent))
        marc_matches = marc_matches.partition {|marc| get_years(marc).include?( year )}.flatten
      end
      # And add in the 856's
      add_856_links(request, marc_matches, :match_reliability => ServiceResponse::MatchUnsure)

      # Fetch and add in the holdings
      url = blacklight_url_for_ids(bib_ids_from_atom_entries(entries))
      
      holdings_added += add_holdings( url, :match_reliability => ServiceResponse::MatchUnsure, :marc_data => marc_by_atom_id ) if url
      
      if (@link_to_search && holdings_added ==0)
        hit_count = doc.at_xpath("atom:feed/opensearch:totalResults/text()", xml_ns).to_s.to_i
        html_result_url = doc.at_xpath("atom:feed/atom:link[@rel='alternate'][@type='text/html']/attribute::href", xml_ns).to_s

        if hit_count > 0          
          request.add_service_response(             
            :service => self,
            :source_name => @display_name,
            :count => hit_count,
            :display_text => "#{hit_count} possible #{case; when hit_count > 1 ; 'matches' ; else; 'match' ; end} in #{@display_name}", 
            :url => html_result_url,
            :service_type_value => :holding_search )
        end
      end
  end


  
  
  return request.dispatched(self, true)


end

#service_types_generatedObject

Standard method, used by background service updater. See Service docs.


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# File 'app/service_adaptors/blacklight.rb', line 63

def service_types_generated    
  types = [ ServiceTypeValue[:fulltext], ServiceTypeValue[:holding], ServiceTypeValue[:table_of_contents], ServiceTypeValue[:relevant_link] ]
  
  return types
end