From 53f18f2c5475809f7f6c5576aba89d6340a57c06 Mon Sep 17 00:00:00 2001 From: Aaron Weiner Date: Wed, 27 Feb 2013 18:17:29 -0500 Subject: [PATCH] More helpful error message when instantiating an abstract class Calling a literal ActiveRecord::Base.new raises NoMethodError, since it ends up calling Class.abstract_class? which does not exist. Similarly, instantiating an actual abstract class hits the database, when conventionally it should immediately throw NotImplementedError. ActiveRecord::Base can't be made abstract without breaking many, many things, so check for it separately. --- activerecord/CHANGELOG.md | 4 ++++ activerecord/lib/active_record/inheritance.rb | 3 +++ activerecord/test/cases/base_test.rb | 14 ++++++++++++++ 3 files changed, 21 insertions(+) diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index 2eaf388095..2f96a7b5cf 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,5 +1,9 @@ ## Rails 4.0.0 (unreleased) ## +* Throw `NotImplementedError` when trying to instantiate Base or an abstract class. + + *Aaron Weiner* + * Postgresql timestamp with time zone (timestamptz) datatype now returns a ActiveSupport::TimeWithZone instance instead of a string diff --git a/activerecord/lib/active_record/inheritance.rb b/activerecord/lib/active_record/inheritance.rb index e630897a4b..13a8352f13 100644 --- a/activerecord/lib/active_record/inheritance.rb +++ b/activerecord/lib/active_record/inheritance.rb @@ -15,6 +15,9 @@ module ActiveRecord # and if the inheritance column is attr accessible, it initializes an # instance of the given subclass instead of the base class def new(*args, &block) + if abstract_class? || self == Base + raise NotImplementedError, "#{self} is an abstract class and can not be instantiated." + end if (attrs = args.first).is_a?(Hash) if subclass = subclass_from_attrs(attrs) return subclass.new(*args, &block) diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb index af1845c937..8e6e462404 100644 --- a/activerecord/test/cases/base_test.rb +++ b/activerecord/test/cases/base_test.rb @@ -307,6 +307,20 @@ class BasicsTest < ActiveRecord::TestCase assert_equal("last_read", ex.errors[0].attribute) end + def test_initialize_abstract_class + e = assert_raises(NotImplementedError) do + FirstAbstractClass.new + end + assert_equal("FirstAbstractClass is an abstract class and can not be instantiated.", e.message) + end + + def test_initialize_base + e = assert_raises(NotImplementedError) do + ActiveRecord::Base.new + end + assert_equal("ActiveRecord::Base is an abstract class and can not be instantiated.", e.message) + end + def test_create_after_initialize_without_block cb = CustomBulb.create(:name => 'Dude') assert_equal('Dude', cb.name)