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Rails 4.0.0 (unreleased)

  • Rails now raise an exception when you're trying to run a migration that has an invalid file name. Only lower case letters, numbers, and '_' are allowed in migration's file name. Please see #7419 for more details.

    Jan Bernacki

  • Fix bug when call store_accessor multiple times. Fixes #7532.

    Matt Jones

  • Fix store attributes that show the changes incorrectly. Fixes #7532.

    Matt Jones

  • Fix ActiveRecord::Relation#pluck when columns or tables are reserved words.

    Ian Lesperance

  • Allow JSON columns to be created in PostgreSQL and properly encoded/decoded to/from database.

    Dickson S. Guedes

  • Fix time column type casting for invalid time string values to correctly return nil.

    Adam Meehan

  • Allow to pass Symbol or Proc into :limit option of #accepts_nested_attributes_for

    Mikhail Dieterle

  • ActiveRecord::SessionStore has been extracted from Active Record as activerecord-session_store gem. Please read the file on the gem for the usage. Prem Sichanugrist

  • Fix reset_counters when there are multiple belongs_to association with the same foreign key and one of them have a counter cache. Fixes #5200.

    Dave Desrochers

  • serialized_attributes and _attr_readonly become class method only. Instance reader methods are deprecated.


  • Round usec when comparing timestamp attributes in the dirty tracking. Fixes #6975.


  • Use inversed parent for first and last child of has_many association.

    Ravil Bayramgalin

  • Fix Column.microseconds and Column.fast_string_to_date to avoid converting timestamp seconds to a float, since it occasionally results in inaccuracies with microsecond-precision times. Fixes #7352.

    Ari Pollak

  • Raise ArgumentError if list of attributes to change is empty in update_all.

    Roman Shatsov

  • Fix AR#create to return an unsaved record when AR::RecordInvalid is raised. Fixes #3217.

    Dave Yeu

  • Fixed table name prefix that is generated in engines for namespaced models Wojciech Wnętrzak

  • Make sure :environment task is executed before db:schema:load or db:structure:load Fixes #4772.

    Seamus Abshere

  • Allow Relation#merge to take a proc.

    This was requested by DHH to allow creating of one's own custom association macros.

    For example:

    module Commentable
      def has_many_comments(extra)
        has_many :comments, -> { where(:foo).merge(extra) }
    class Post < ActiveRecord::Base
      extend Commentable
      has_many_comments -> { where(:bar) }

    Jon Leighton

  • Add CollectionProxy#scope

    This can be used to get a Relation from an association.

    Previously we had a #scoped method, but we're deprecating that for AR::Base, so it doesn't make sense to have it here.

    This was requested by DHH, to facilitate code like this:

    Project.scope.order('created_at DESC').page(current_page).tagged_with(@tag).limit(5).scoping do
      @topics      = @project.topics.scope
      @todolists   = @project.todolists.scope
      @attachments = @project.attachments.scope
      @documents   = @project.documents.scope

    Jon Leighton

  • Add Relation#load

    This method explicitly loads the records and then returns self.

    Rather than deciding between "do I want an array or a relation?", most people are actually asking themselves "do I want to eager load or lazy load?" Therefore, this method provides a way to explicitly eager-load without having to switch from a Relation to an array.


    @posts = Post.where(published: true).load

    Jon Leighton

  • Model.all now returns an ActiveRecord::Relation, rather than an array of records. Use `Relation#to_a if you really want an array.

    In some specific cases, this may cause breakage when upgrading. However in most cases the ActiveRecord::Relation will just act as a lazy-loaded array and there will be no problems.

    Note that calling Model.all with options (e.g. Model.all(conditions: '...') was already deprecated, but it will still return an array in order to make the transition easier.

    Model.scoped is deprecated in favour of Model.all.

    Relation#all still returns an array, but is deprecated (since it would serve no purpose if we made it return a Relation).

    Jon Leighton

  • :finder_sql and :counter_sql options on collection associations are deprecated. Please transition to using scopes.

    Jon Leighton

  • :insert_sql and :delete_sql options on has_and_belongs_to_many associations are deprecated. Please transition to using has_many :through

    Jon Leighton

  • The migration generator now creates a join table with (commented) indexes every time the migration name contains the word join_table:

    rails g migration create_join_table_for_artists_and_musics artist_id:index music_id

    Aleksey Magusev

  • Add add_reference and remove_reference schema statements. Aliases, add_belongs_to and remove_belongs_to are acceptable. References are reversible. Examples:

    # Create a user_id column
    add_reference(:products, :user)
    # Create a supplier_id, supplier_type columns and appropriate index
    add_reference(:products, :supplier, polymorphic: true, index: true)
    # Remove polymorphic reference
    remove_reference(:products, :supplier, polymorphic: true)

    Aleksey Magusev

  • Add :default and :null options to column_exists?.

    column_exists?(:testings, :taggable_id, :integer, null: false)
    column_exists?(:testings, :taggable_type, :string, default: 'Photo')

    Aleksey Magusev

  • ActiveRecord::Relation#inspect now makes it clear that you are dealing with a Relation object rather than an array:.

    User.where(:age => 30).inspect
    # => <ActiveRecord::Relation [#<User ...>, #<User ...>, ...]>
    User.where(:age => 30).to_a.inspect
    # => [#<User ...>, #<User ...>]

    The number of records displayed will be limited to 10.

    Brian Cardarella, Jon Leighton & Damien Mathieu

  • Add collation and ctype support to PostgreSQL. These are available for PostgreSQL 8.4 or later. Example:

      adapter: postgresql
      host: localhost
      database: rails_development
      username: foo
      password: bar
      encoding: UTF8
      collation: ja_JP.UTF8
      ctype: ja_JP.UTF8


  • Changed validates_presence_of on an association so that children objects do not validate as being present if they are marked for destruction. This prevents you from saving the parent successfully and thus putting the parent in an invalid state.

    Nick Monje & Brent Wheeldon

  • FinderMethods#exists? now returns false with the false argument.

    Egor Lynko

  • Added support for specifying the precision of a timestamp in the postgresql adapter. So, instead of having to incorrectly specify the precision using the :limit option, you may use :precision, as intended. For example, in a migration:

    def change
      create_table :foobars do |t|
        t.timestamps :precision => 0

    Tony Schneider

  • Allow ActiveRecord::Relation#pluck to accept multiple columns. Returns an array of arrays containing the typecasted values:

    Person.pluck(:id, :name)
    # SELECT, FROM people
    # [[1, 'David'], [2, 'Jeremy'], [3, 'Jose']]

    Jeroen van Ingen & Carlos Antonio da Silva

  • Improve the derivation of HABTM join table name to take account of nesting. It now takes the table names of the two models, sorts them lexically and then joins them, stripping any common prefix from the second table name.

    Some examples:

    Top level models (Category <=> Product)
    Old: categories_products
    New: categories_products
    Top level models with a global table_name_prefix (Category <=> Product)
    Old: site_categories_products
    New: site_categories_products
    Nested models in a module without a table_name_prefix method (Admin::Category <=> Admin::Product)
    Old: categories_products
    New: categories_products
    Nested models in a module with a table_name_prefix method (Admin::Category <=> Admin::Product)
    Old: categories_products
    New: admin_categories_products
    Nested models in a parent model (Catalog::Category <=> Catalog::Product)
    Old: categories_products
    New: catalog_categories_products
    Nested models in different parent models (Catalog::Category <=> Content::Page)
    Old: categories_pages
    New: catalog_categories_content_pages

    Andrew White

  • Move HABTM validity checks to ActiveRecord::Reflection. One side effect of this is to move when the exceptions are raised from the point of declaration to when the association is built. This is consistant with other association validity checks.

    Andrew White

  • Added stored_attributes hash which contains the attributes stored using ActiveRecord::Store. This allows you to retrieve the list of attributes you've defined.

    class User < ActiveRecord::Base store :settings, accessors: [:color, :homepage] end

    User.stored_attributes[:settings] # [:color, :homepage]

    Joost Baaij & Carlos Antonio da Silva

  • PostgreSQL default log level is now 'warning', to bypass the noisy notice messages. You can change the log level using the min_messages option available in your config/database.yml.


  • Add uuid datatype support to PostgreSQL adapter. Konstantin Shabanov

  • Added ActiveRecord::Migration.check_pending! that raises an error if migrations are pending. Richard Schneeman

  • Added #destroy! which acts like #destroy but will raise an ActiveRecord::RecordNotDestroyed exception instead of returning false.

    Marc-André Lafortune

  • Allow blocks for count with ActiveRecord::Relation, to work similar as Array#count:

    Person.where("age > 26").count { |person| person.gender == 'female' }

    Chris Finne & Carlos Antonio da Silva

  • Added support to CollectionAssociation#delete for passing fixnum or string values as record ids. This finds the records responding to the id and executes delete on them.

    class Person < ActiveRecord::Base
      has_many :pets
    person.pets.delete("1") # => [#<Pet id: 1>]
    person.pets.delete(2, 3) # => [#<Pet id: 2>, #<Pet id: 3>]

    Francesco Rodriguez

  • Deprecated most of the 'dynamic finder' methods. All dynamic methods except for find_by_... and find_by_...! are deprecated. Here's how you can rewrite the code:

    • find_all_by_... can be rewritten using where(...)
    • find_last_by_... can be rewritten using where(...).last
    • scoped_by_... can be rewritten using where(...)
    • find_or_initialize_by_... can be rewritten using where(...).first_or_initialize
    • find_or_create_by_... can be rewritten using where(...).first_or_create
    • find_or_create_by_...! can be rewritten using where(...).first_or_create!

    The implementation of the deprecated dynamic finders has been moved to the activerecord-deprecated_finders gem. See below for details.

    Jon Leighton

  • Deprecated the old-style hash based finder API. This means that methods which previously accepted "finder options" no longer do. For example this:

    Post.find(:all, :conditions => { :comments_count => 10 }, :limit => 5)

    Should be rewritten in the new style which has existed since Rails 3:

    Post.where(comments_count: 10).limit(5)

    Note that as an interim step, it is possible to rewrite the above as:

    Post.all.merge(:where => { :comments_count => 10 }, :limit => 5)

    This could save you a lot of work if there is a lot of old-style finder usage in your application.

    Relation#merge now accepts a hash of options, but they must be identical to the names of the equivalent finder method. These are mostly identical to the old-style finder option names, except in the following cases:

    • :conditions becomes :where
    • :include becomes :includes
    • :extend becomes :extending

    The code to implement the deprecated features has been moved out to the activerecord-deprecated_finders gem. This gem is a dependency of Active Record in Rails 4.0. It will no longer be a dependency from Rails 4.1, but if your app relies on the deprecated features then you can add it to your own Gemfile. It will be maintained by the Rails core team until Rails 5.0 is released.

    Jon Leighton

  • It's not possible anymore to destroy a model marked as read only.

    Johannes Barre

  • Added ability to ActiveRecord::Relation#from to accept other ActiveRecord::Relation objects

    Record.from(subquery) Record.from(subquery, :a)

    Radoslav Stankov

  • Added custom coders support for ActiveRecord::Store. Now you can set your custom coder like this:

    store :settings, accessors: [ :color, :homepage ], coder: JSON

    Andrey Voronkov

  • mysql and mysql2 connections will set SQL_MODE=STRICT_ALL_TABLES by default to avoid silent data loss. This can be disabled by specifying strict: false in your database.yml.

    Michael Pearson

  • Added default order to first to assure consistent results among diferent database engines. Introduced take as a replacement to the old behavior of first.

    Marcelo Silveira

  • Added an :index option to automatically create indexes for references and belongs_to statements in migrations.

    The references and belongs_to methods now support an index option that receives either a boolean value or an options hash that is identical to options available to the add_index method:

    create_table :messages do |t| t.references :person, :index => true end

    Is the same as:

    create_table :messages do |t| t.references :person end add_index :messages, :person_id

    Generators have also been updated to use the new syntax.

    [Joshua Wood]

  • Added bang methods for mutating ActiveRecord::Relation objects. For example, while foo.where(:bar) will return a new object leaving foo unchanged, foo.where!(:bar) will mutate the foo object

    Jon Leighton

  • Added #find_by and #find_by! to mirror the functionality provided by dynamic finders in a way that allows dynamic input more easily:

    Post.find_by name: 'Spartacus', rating: 4
    Post.find_by "published_at < ?", 2.weeks.ago
    Post.find_by! name: 'Spartacus'

    Jon Leighton

  • Added ActiveRecord::Base#slice to return a hash of the given methods with their names as keys and returned values as values.

    Guillermo Iguaran

  • Deprecate eager-evaluated scopes.

    Don't use this:

    scope :red, where(color: 'red')
    default_scope where(color: 'red')

    Use this:

    scope :red, -> { where(color: 'red') }
    default_scope { where(color: 'red') }

    The former has numerous issues. It is a common newbie gotcha to do the following:

    scope :recent, where(published_at: - 2.weeks)

    Or a more subtle variant:

    scope :recent, -> { where(published_at: - 2.weeks) }
    scope :recent_red, recent.where(color: 'red')

    Eager scopes are also very complex to implement within Active Record, and there are still bugs. For example, the following does not do what you expect:

    scope :remove_conditions, except(:where)
    where(...).remove_conditions # => still has conditions

    Jon Leighton

  • Remove IdentityMap

    IdentityMap has never graduated to be an "enabled-by-default" feature, due to some inconsistencies with associations, as described in this commit:

    Hence the removal from the codebase, until such issues are fixed.

    Carlos Antonio da Silva

  • Added the schema cache dump feature.

    Schema cache dump feature was implemetend. This feature can dump/load internal state of SchemaCache instance because we want to boot rails more quickly when we have many models.

    Usage notes:

    1) execute rake task. RAILS_ENV=production bundle exec rake db:schema:cache:dump => generate db/schema_cache.dump

    2) add config.active_record.use_schema_cache_dump = true in config/production.rb. BTW, true is default.

    3) boot rails. RAILS_ENV=production bundle exec rails server => use db/schema_cache.dump

    4) If you remove clear dumped cache, execute rake task. RAILS_ENV=production bundle exec rake db:schema:cache:clear => remove db/schema_cache.dump


  • Added support for partial indices to PostgreSQL adapter

    The add_index method now supports a where option that receives a string with the partial index criteria.

    add_index(:accounts, :code, :where => "active")
    CREATE INDEX index_accounts_on_code ON accounts(code) WHERE active

    Marcelo Silveira

  • Implemented ActiveRecord::Relation#none method

    The none method returns a chainable relation with zero records (an instance of the NullRelation class).

    Any subsequent condition chained to the returned relation will continue generating an empty relation and will not fire any query to the database.

    Juanjo Bazán

  • Added the ActiveRecord::NullRelation class implementing the null object pattern for the Relation class. Juanjo Bazán

  • Added new :dependent => :restrict_with_error option. This will add an error to the model, rather than raising an exception.

    The :restrict option is renamed to :restrict_with_exception to make this distinction explicit.

    Manoj Kumar & Jon Leighton

  • Added create_join_table migration helper to create HABTM join tables

    create_join_table :products, :categories
    # =>
    # create_table :categories_products, :id => false do |td|
    #   td.integer :product_id, :null => false
    #   td.integer :category_id, :null => false
    # end

    Rafael Mendonça França

  • The primary key is always initialized in the @attributes hash to nil (unless another value has been specified).

  • In previous releases, the following would generate a single query with an OUTER JOIN comments, rather than two separate queries:

        .where(" = 'foo'")

    This behaviour relies on matching SQL string, which is an inherently flawed idea unless we write an SQL parser, which we do not wish to do.

    Therefore, it is now deprecated.

    To avoid deprecation warnings and for future compatibility, you must explicitly state which tables you reference, when using SQL snippets:

        .where(" = 'foo'")

    Note that you do not need to explicitly specify references in the following cases, as they can be automatically inferred:

    Post.where(comments: { name: 'foo' })
    Post.where('' => 'foo')

    You also do not need to worry about this unless you are doing eager loading. Basically, don't worry unless you see a deprecation warning or (in future releases) an SQL error due to a missing JOIN.

    [Jon Leighton]

  • Support for the schema_info table has been dropped. Please switch to schema_migrations.

  • Connections must be closed at the end of a thread. If not, your connection pool can fill and an exception will be raised.

  • Added the ActiveRecord::Model module which can be included in a class as an alternative to inheriting from ActiveRecord::Base:

    class Post
      include ActiveRecord::Model

    Please note:

    • Up until now it has been safe to assume that all AR models are descendants of ActiveRecord::Base. This is no longer a safe assumption, but it may transpire that there are areas of the code which still make this assumption. So there may be 'teething difficulties' with this feature. (But please do try it and report bugs.)

    • Plugins & libraries etc that add methods to ActiveRecord::Base will not be compatible with ActiveRecord::Model. Those libraries should add to ActiveRecord::Model instead (which is included in Base), or better still, avoid monkey-patching AR and instead provide a module that users can include where they need it.

    • To minimise the risk of conflicts with other code, it is advisable to include ActiveRecord::Model early in your class definition.

    Jon Leighton

  • PostgreSQL hstore records can be created.

  • PostgreSQL hstore types are automatically deserialized from the database.

Rails 3.2.8 (Aug 9, 2012)

  • Do not consider the numeric attribute as changed if the old value is zero and the new value is not a string. Fixes #7237.

    Rafael Mendonça França

  • Removes the deprecation of update_attribute. fxn

  • Reverted the deprecation of composed_of. Rafael Mendonça França

  • Reverted the deprecation of *_sql association options. They will be deprecated in 4.0 instead. Jon Leighton

  • Do not eager load AR session store. ActiveRecord::SessionStore depends on the abstract store in Action Pack. Eager loading this class would break client code that eager loads Active Record standalone. Fixes #7160

    Xavier Noria

  • Do not set RAILS_ENV to "development" when using db:test:prepare and related rake tasks. This was causing the truncation of the development database data when using RSpec. Fixes #7175.

    Rafael Mendonça França

Rails 3.2.7 (Jul 26, 2012)

  • :finder_sql and :counter_sql options on collection associations are deprecated. Please transition to using scopes.

    Jon Leighton

  • :insert_sql and :delete_sql options on has_and_belongs_to_many associations are deprecated. Please transition to using has_many :through

    Jon Leighton

  • composed_of has been deprecated. You'll have to write your own accessor and mutator methods if you'd like to use value objects to represent some portion of your models.

    Steve Klabnik

  • update_attribute has been deprecated. Use update_column if you want to bypass mass-assignment protection, validations, callbacks, and touching of updated_at. Otherwise please use update_attributes.

    Steve Klabnik

Rails 3.2.6 (Jun 12, 2012)

  • protect against the nesting of hashes changing the table context in the next call to build_from_hash. This fix covers this case as well.


  • Revert earlier 'perf fix' (see 3.2.4 changelog / GH #6289). This change introduced a regression (GH #6609). assoc.clear and assoc.delete_all have loaded the association before doing the delete since at least Rails 2.3. Doing the delete without loading the records means that the before_remove and after_remove callbacks do not get invoked. Therefore, this change was less a fix a more an optimisation, which should only have gone into master.

    Jon Leighton

Rails 3.2.5 (Jun 1, 2012)

  • Restore behavior of Active Record 3.2.3 scopes. A series of commits relating to preloading and scopes caused a regression.

    Andrew White

Rails 3.2.4 (May 31, 2012)

  • Perf fix: Don't load the records when doing assoc.delete_all. GH #6289. Jon Leighton

  • Association preloading shouldn't be affected by the current scoping. This could cause infinite recursion and potentially other problems. See GH #5667. Jon Leighton

  • Datetime attributes are forced to be changed. GH #3965

  • Fix attribute casting. GH #5549

  • Fix #5667. Preloading should ignore scoping.

  • Predicate builder should not recurse for determining where columns. Thanks to Ben Murphy for reporting this! CVE-2012-2661

Please check 3-2-stable for previous changes.

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