couch-client.rb

require 'rest_client'
require 'json'
require 'pp'

COUCHDB = "http://localhost:5984/dbname"

filters_doc = {
  "_id" => "_design/app",
  "filters" => {
      "people"=> "function(doc, req) { return doc.type == 'person' }"
  }
}

class JsonApiClient < RestClient::Resource
	DEFAULT_OPTIONS = {:content_type => :json, :accept => :json}

	def get_with_json(*args, &block)
		r = get_without_json(*args,&block)
		JSON.parse(r)
	end

	alias_method :get_without_json, :get
	alias_method :get, :get_with_json

	def post_with_json(content, options={}, &block)
		options = options.merge(DEFAULT_OPTIONS)
		content = parse_content(content)
		r = post_without_json(content, options, &block)
		JSON.parse(r)
	end

	alias_method :post_without_json, :post
	alias_method :post, :post_with_json

	def put_with_json(content, options={}, &block)
		options = options.merge(DEFAULT_OPTIONS)
		content = parse_content(content)
		r = put_without_json(content, options, &block)
		JSON.parse(r)
	end

	alias_method :put_without_json, :put
	alias_method :put, :put_with_json

	def delete_with_json(*args, &block)
		r = delete_without_json(*args,&block)
		JSON.parse(r)
	end

	alias_method :delete_without_json, :delete
	alias_method :delete, :delete_with_json

	private

	def parse_content(content)
		content = content.to_json if content.is_a? Hash
		content
	end

end

class CouchClient < JsonApiClient
	def create_or_update(doc)
		id = doc["_id"] || doc[:_id]
		rev = self[id].get["_rev"]
		doc["_rev"] = rev
		# update
		self[id].put(doc)
		rescue RestClient::ResourceNotFound
			# create
			self.post(doc)
	end

	def changes(params={}, &block)
		loop do
		  res = self["_changes"].get(params: params)
		  params[:since] = res["last_seq"]
		  res["results"].each(&block)
		  break if res["results"].empty?
		end
		params[:since] || 0
	end
end


couch = CouchClient.new(COUCHDB)

couch.create_or_update(filters_doc)

since = couch[".since"].get{|r| r }["since"] || 0

since = couch.changes(since: since, limit: 50, filter:"app/people", include_docs: "true") do |hash|
	if hash["deleted"]
		puts "deleted: #{hash['id']}"
	else
		puts "updated: #{hash['id']}"
		pp hash["doc"]
	end
end

puts since
couch.create_or_update(_id: ".since", type: "metadata", since: since)