clarkdave · July 18, 2019 15:37 · kernel-io · Aug 3, 2014 · aks · May 18, 2015
diff --git a/pg_enum.rb b/pg_enum.rb
 ##
 # This provides `create_enum` and `drop_enum` methods for migrations, which creates
 # a Postgres ENUM type with the provided values.
 #
 # It'll also dump these into the schema.rb to be loaded into another DB (e.g. rake db:test:load)
 #
 # In order to reference the new enums as actual types, ActiveRecord needs to know about them, so
 # make sure they are all represented in the `types` array below
 #
 # Then you can reference them in your migrations, e.g.
 # 
 # create_table :example do
 #   t.state :state
 #   t.location :location
 #   t.method :method
 # end
 ##

 types = %w(state location method)

 module PgEnum
  
  # provide the enum DDL methods
  module PostgreSQLAdapter
    def create_enum(name, values)
      values = values.map {|v| "'#{v}'"}
      execute "CREATE TYPE #{name} AS ENUM (#{values.join(', ')})"
    end

    def drop_enum(name)
      execute "DROP TYPE #{name}"
    end
  end

  # provide support for writing out the 'create_enum' calls in schema.rb
  module SchemaDumper
    extend ActiveSupport::Concern

    included do
      alias_method_chain :tables, :enums
    end

    def tables_with_enums(stream)
      enums(stream)
      tables_without_enums(stream)
    end

    private
    def enums(stream)
      enums = @connection.select_all("SELECT typname FROM pg_type WHERE typtype = 'e'").map{|r| r['typname']}

      statements = []

      enums.each do |enum|
        values = @connection.select_all(
          "SELECT e.enumlabel FROM pg_enum e JOIN pg_type t ON e.enumtypid = t.oid WHERE t.typname = '#{enum}'"
        ).map {|v| v['enumlabel'].inspect }.join(', ')

        statements << "  create_enum(#{enum.inspect}, [#{values}])"
      end

      stream.puts statements.join("\n")
      stream.puts
    end
  end
 end


 class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
  include PgEnum::PostgreSQLAdapter
 end

 module ActiveRecord::ConnectionAdapters
  include PgEnum::PostgreSQLAdapter
 end

 class ActiveRecord::SchemaDumper
  include PgEnum::SchemaDumper
 end

 # make activerecord aware of our enum types

 types.each do |type|
  ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::NATIVE_DATABASE_TYPES[type.to_sym] = { name: type }

  ActiveRecord::ConnectionAdapters::Column.class_eval do
    
    define_method("simplified_type_with_#{type}") do |field_type|
      if field_type == type
        field_type.to_sym
      else
        send("simplified_type_without_#{type}", field_type)
      end
    end

    alias_method_chain :simplified_type, type
  end

  ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::TableDefinition.class_eval do

    define_method(type) do |*args|
      options = args.extract_options!
      column(args[0], type, options)
    end
  end

  ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::OID.alias_type type, 'text'
  
  ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.tap do |clazz|
    clazz::OID.register_type(type, clazz::OID::Identity.new)
  end
 end
	##
	# This provides `create_enum` and `drop_enum` methods for migrations, which creates
	# a Postgres ENUM type with the provided values.
	#
	# It'll also dump these into the schema.rb to be loaded into another DB (e.g. rake db:test:load)
	#
	# In order to reference the new enums as actual types, ActiveRecord needs to know about them, so
	# make sure they are all represented in the `types` array below
	#
	# Then you can reference them in your migrations, e.g.
	#
	# create_table :example do
	# t.state :state
	# t.location :location
	# t.method :method
	# end
	##

	types = %w(state location method)

	module PgEnum

	# provide the enum DDL methods
	module PostgreSQLAdapter
	def create_enum(name, values)
	values = values.map {\|v\| "'#{v}'"}
	execute "CREATE TYPE #{name} AS ENUM (#{values.join(', ')})"
	end

	def drop_enum(name)
	execute "DROP TYPE #{name}"
	end
	end

	# provide support for writing out the 'create_enum' calls in schema.rb
	module SchemaDumper
	extend ActiveSupport::Concern

	included do
	alias_method_chain :tables, :enums
	end

	def tables_with_enums(stream)
	enums(stream)
	tables_without_enums(stream)
	end

	private
	def enums(stream)
	enums = @connection.select_all("SELECT typname FROM pg_type WHERE typtype = 'e'").map{\|r\| r['typname']}

	statements = []

	enums.each do \|enum\|
	values = @connection.select_all(
	"SELECT e.enumlabel FROM pg_enum e JOIN pg_type t ON e.enumtypid = t.oid WHERE t.typname = '#{enum}'"
	).map {\|v\| v['enumlabel'].inspect }.join(', ')

	statements << " create_enum(#{enum.inspect}, [#{values}])"
	end

	stream.puts statements.join("\n")
	stream.puts
	end
	end
	end


	class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter
	include PgEnum::PostgreSQLAdapter
	end

	module ActiveRecord::ConnectionAdapters
	include PgEnum::PostgreSQLAdapter
	end

	class ActiveRecord::SchemaDumper
	include PgEnum::SchemaDumper
	end

	# make activerecord aware of our enum types

	types.each do \|type\|
	ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::NATIVE_DATABASE_TYPES[type.to_sym] = { name: type }

	ActiveRecord::ConnectionAdapters::Column.class_eval do

	define_method("simplified_type_with_#{type}") do \|field_type\|
	if field_type == type
	field_type.to_sym
	else
	send("simplified_type_without_#{type}", field_type)
	end
	end

	alias_method_chain :simplified_type, type
	end

	ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::TableDefinition.class_eval do

	define_method(type) do \|*args\|
	options = args.extract_options!
	column(args[0], type, options)
	end
	end

	ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::OID.alias_type type, 'text'

	ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.tap do \|clazz\|
	clazz::OID.register_type(type, clazz::OID::Identity.new)
	end
	end