by_content_type.map.js

function(doc) {
  emit(doc.content_type, doc);
}

by_content_type.reduce.js

_count

couch.rake

namespace :couchdb do
  task :migrate => :environment do
    databases = Database.all

    if (Rails.env.development? || Rails.env.test?) && ENV['DELAY_COUCH_MIGRATIONS'].nil?
      puts "-> Migrating CouchDB"
      databases.each do |d|
        puts "-> Migrating #{d.couch_db_name}"
        Schema.migrate( CouchRest::database!(d.couch_url))
      end
    else
      puts "-> Delayed Migrating CouchDB"
      databases.each do |d|
        puts "-> Storing Migrate Job for #{d.couch_db_name}"
        Resque.enqueue CouchMigrate, d.couch_url
      end
    end

  end
end

couch_migrate_job.rb

class CouchMigrate
  @queue = :migrations

  def self.perform(db)
    Schema.migrate CouchRest::database!(db)
  end

end

schema.rb

module Schema

  class << self

    @@views = [
      "resources"
    ]
    @@db = nil

    def migrate(db=nil)
      raise "ERROR: You need to provide a CouchRest::Database to migrate." unless (db.present? || !db.kind_of?(::CouchRest::Database))
      @@db = db
      @@views.each do |view|
        klass = "Schema::#{view.camelcase}".constantize.new(db)
        klass.save
      end
    end

  end

end

class Schema::View

  attr_accessor :document, :version, :db

  def view_name
    self.class.to_s.split("::").last.downcase
  end

  def initialize(db)
    @db       ||= db
    @views    ||= self.class.views
    @version  ||= self.class.version
  end

  @@base_path = "#{Rails.root}/app/couch/schema/"

  def views
    tmp = {}
    @views.each do |key, values|
      map_view_path = File.join(@@base_path, view_name, "#{key.to_s}.map.js")
      reduce_view_path = File.join(@@base_path, view_name, "#{key.to_s}.reduce.js")
      puts "Couchdb WARNING: #{map_view_path} not present" unless File.exists?(map_view_path)
      if File.exists?(map_view_path)
        values[:map] = File.open(map_view_path).read
      end
      if File.exists?(reduce_view_path) && values[:reduce]
        values[:reduce] = File.open(reduce_view_path).read
      else
        values.delete(:reduce)
      end
      tmp[key] = values
    end
    tmp
  end

  def design
    d = {
      _id: "_design/#{view_name}",
      version: version,
      views: views
    }
  end

  def get_document
    @db.get(design[:_id])
  end

  def document
    begin
      @document ||= get_document
    rescue RestClient::ResourceNotFound
      return nil
    end
    @document
  end

  def needs_updating?
    current_version = document["version"]
    current_version.nil? || current_version < version
  end

  def save
    if document && needs_updating?
      updated = document.merge(design.stringify_keys)
      puts "Document #{design[:_id]} version:#{design[:version]} updating from version #{document['version']}"
      @db.save_doc( updated )
    elsif !document
      puts "Document #{design[:_id]} version:#{design[:version]} importing new view"
      @db.save_doc( design.stringify_keys )
    else
      puts "Document #{design[:_id]} version:#{design[:version]} no update required"
    end
  end

end

schema_resources.rb

class Schema::Resources < Schema::View

  def self.version
    14
  end

  def self.views
    {
      by_content_type: {
        map: true
      },
      by_content_type_and_code: {
        map: true,
        reduce: true
      },
      by_content_type_and_error_count: {
        map: true,
        reduce: true
      },
      by_run_id: {
        map: true,
        reduce: true
      }
    }
  end

end