blacklight_oai_provider.rb

require 'dispatcher'
require 'oai'
require 'rsolr'
require 'rsolr-ext'

module OAI_DocumentPatch
	def self.included(base)
		base.extend(ClassMethods)
		base.send(:include, InstanceMethods)
	end
	
	module ClassMethods
	
	end
	
	module InstanceMethods
		def to_oai_dc
			xml = Builder::XmlMarkup.new
			xml.tag!("oai_dc:dc",
				'xmlns:oai_dc' => "http://www.openarchives.org/OAI/2.0/oai_dc/",
				'xmlns:dc' => "http://purl.org/dc/elements/1.1/",
				'xmlns:xsi' => "http://www.w3.org/2001/XMLSchema-instance",
				'xsi:schemaLocation' =>
				%{http://www.openarchives.org/OAI/2.0/oai_dc/
				http://www.openarchives.org/OAI/2.0/oai_dc.xsd}) do
					Blacklight.config[:oai][:map].each do |k, v|
						f = get(k)
						f = [f] if f.class != Array
						begin
							f.each { |r| xml.tag!(v, r) }
						end
					end
				end
			xml.target!		
		end
		
		def timestamp
			Time.parse get('timestamp')
		end
	end
end

module OAI
	module Provider
		class SolrDocumentWrapper < Model
			attr_reader :model, :timestamp_field
			 def initialize(model, options={})
		      @model = model
		      @timestamp_field = options.delete(:timestamp_field) || 'timestamp'
		      @limit = options.delete(:limit)
		
		      unless options.empty?
		        raise ArgumentError.new(
		          "Unsupported options [#{options.keys.join(', ')}]"
		        )
		      end
		    end
		    
		    def deleted? record
		    	false
		    end
		    
		    def earliest
		    	 Time.parse model.search({:sort => 'timestamp asc', :rows => 1}).docs[0].get('timestamp')
		    end
		    
		    def find(selector, options={})
		    	return next_set(options[:resumption_token]) if options[:resumption_token]
		    	if :all == selector
		    		records = model.search({:sort => 'timestamp asc', :rows => @limit}).docs
		    		total = records.count
		    		
		    		if @limit && total >= @limit
		    			return select_partial ResumptionToken.new options.merge({:last => 0})
		    		end
		    	else
		    		records = model.find_by_id({:id => selector}).docs[0]
		    	end	
		    	records
		    end
			
		    def latest
		    	 Time.parse model.search({:sort => 'timestamp desc', :rows => 1}).docs[0].get('timestamp')
		    end
		    
		    def sets
		    
		    end
		    
		    def select_partial token
		    	records = model.search({:sort => 'timestamp asc', :rows => @limit, :start => token.last}).docs
		    
		    	raise OAI::ResumptionTokenException.new unless records
		    	
		     	PartialResult.new(records, token.next(@limit + token.last))
		    end
		    
		    def next_set(token_string)
		    	raise OAI::ResumptionTokenException.new unless @limit
		    	
		    	token = ResumptionToken.parse token_string
		    	select_partial token	    	
		    end
		end
		
		class SolrDocumentProvider < Base
		    repository_name 'My OAI Provider'
		    repository_url 'http://localhost:3000/oai/'
		    record_prefix 'info:fedora'
		    admin_email 'root@localhost'
		    source_model SolrDocumentWrapper.new(SolrDocument)
		end
	end
end

class OaiController < ApplicationController
	def index
		# Remove controller and action from the options.  Rails adds them automatically.
		options = params.delete_if { |k,v| %w{controller action}.include?(k) }
		provider = OAI::Provider::SolrDocumentProvider.new
		response =  provider.process_request(options)
		render :text => response, :content_type => 'text/xml'
	end
end

Dispatcher.to_prepare do
	SolrDocument.send(:include, OAI_DocumentPatch)
end