Rake tasks to list, export & import Mongo DB collections

gistfile1.rb

  namespace :mongo do
    
    def db_name
      Mongoid.database.name
    end

    def db_connection_options
      host, port  = Mongoid.database.connection.host_to_try
      auths       = Mongoid.database.connection.auths

      auth_string = auths.length > 0 ? "-u #{auths[0]["username"]} -p #{auths[0]["password"]}" : ""
      conn_string = "#{auth_string} --host #{host} --port #{port} -d #{db_name}"
      conn_string
    end
          
    desc "Exports all or the specified Mongo collection to JSON files"
    task :export, [:collection] => :environment do |task, args|
      coll_string = args[:collection] ? "-c #{args[:collection]}" : ""
      data_directory = File.join("db", "data", Time.now.strftime("%Y%m%d-%H%m%S"))
      
      cmd = "mongodump #{db_connection_options} #{coll_string} -o #{data_directory}"      
      puts "Executing: #{cmd}#{File::SEPARATOR}#{db_name}"
      `#{cmd}`
      
      Dir.glob("#{File.join(data_directory, db_name)}#{File::SEPARATOR}*.bson").each do |file_name|
        collection_name = file_name.split(".")[0]
        cmd = "bsondump --type json #{file_name} > #{collection_name}.json"
        puts "Executing: #{cmd}"
        `#{cmd}`
      end
      
      puts "Ok"
    end
    
    desc "Imports all or the specified JSON file to the Mongo collection(s)"
    task :import, [:directory, :collection] => :environment do |task, args|
      if args[:collection]
        cmd = "mongoimport #{db_connection_options} -c #{args[:collection]} --type json --file #{File.join(args[:directory], args[:collection])}.json --upsert"
        puts "Executing: #{cmd}"
        `#{cmd}`
      else
        Dir.glob("#{args[:directory]}#{File::SEPARATOR}*.json").each do |file_name|
          collection_name = file_name.split("\/").last.split(".")[0]
          cmd = "mongoimport #{db_connection_options} -c #{collection_name} --type json --file #{file_name} --upsert"
          puts "Executing: #{cmd}"
          `#{cmd}`
        end
      end
    end

    def mongoid_models
      documents = []
      Dir.glob("app/models/**/*.rb").sort.each do |file|
        model_path = file[0..-4].split('/')[2..-1]
        begin
          klass = model_path.map { |path| path.camelize }.join('::').constantize
          if klass.ancestors.include?(Mongoid::Document) && !klass.embedded
            documents << klass
          end
        rescue => e
          # Just for non-mongoid objects that dont have the embedded
          # attribute at the class level.
        end
      end
      documents
    end
    
    desc "List all Mongo DB collections in the database that have a corresponding model class in the application"
    task :list_collections => :environment do
      
      documents = []
      Dir.glob("app/models/**/*.rb").sort.each do |file|
        model_path = file[0..-4].split('/')[2..-1]
        begin
          klass = model_path.map { |path| path.camelize }.join('::').constantize
          documents << klass if klass.ancestors.include?(Mongoid::Document) && !klass.embedded
        rescue
          # Just for non-mongoid objects that dont have the embedded attribute at the class level.
        end
      end
     
      collections = Mongoid.master.collection_names.reject {|cn| cn == "system.indexes" }
      collections.each do |collection|
        puts collection if documents.include?(collection.classify.constantize) rescue NameError # ignore collection if no corresponding model exists
      end
    end
  end