* Support Ruby 2.3 by not unexpectedly calling `.to_proc` on Hash objects

    Fixes #25010

    *tlrdstd*

## Rails 3.2.22 (Jun 16, 2015) ##

* No changes.


## Rails 3.2.19 (Jul 2, 2014) ##

*   Fix SQL Injection Vulnerability in 'bitstring' quoting.

    Fixes CVE-2014-3482.

    *Rafael Mendonça França*


## Rails 3.2.18 (May 6, 2014) ##

* No changes.


## Rails 3.2.17 (Feb 18, 2014) ##

* No changes.


## Rails 3.2.16 (Dec 3, 2013) ##

* No changes.


## Rails 3.2.15 (Oct 16, 2013) ##

*   When calling the method .find_or_initialize_by_* from a collection_proxy
    it should set the inverse_of relation even when the entry was found on the db.

    *arthurnn*

*   Callbacks on has_many should access the in memory parent if a inverse_of is set.

    *arthurnn*

*   Fix `FinderMethods#last` unscoped primary key.

    Fixes #11917.

    *Eugene Kalenkovich*

*   Load fixtures from linked folders.

    *Kassio Borges*

*   When using optimistic locking, `update` was not passing the column to `quote_value`
    to allow the connection adapter to properly determine how to quote the value. This was
    affecting certain databases that use specific colmn types.

    Fixes: #6763

    *Alfred Wong*


## Rails 3.2.14 (Jul 22, 2013) ##

*   Fix merge error when Equality LHS is non-attribute.
    Backport of #7380.

    *Karmes Alexander*

*   Do not re-create destroyed association when saving the parent object.

    Fixes #11450.

    *Paul Nikitochkin*

*   Do not shallow the original exception in `exec_cache` on PostgreSQL adapter.

    Fixes #11260.

    *Rafael Mendonça França*

*   Fix `ActiveRecord::Store` incorrectly tracking changes of its attributes.
    Fixes #10373.

    *Janko Marohnić*

*   Fix a bug that prevented the use of the default STI inheritance column
    (ActiveRecord::Base.inheritance_column = 'some_column'.)

    *chapmajs + Takehiro Adachi*

*   Fix mysql2 adapter raises the correct exception when executing a query on a
    closed connection.

    *Yves Senn*

*   Fixes bug where `Company.new.contract_ids` would incorrectly load
    all non-associated contracts.

    Example:

        company = Company.new # Company has many :contracts

        # before
        company.contract_ids # => SELECT ... WHERE `contracts`.`company_id` IS NULL

        # after
        company.contract_ids # => []

    *Jared Armstrong*

*   Fix the `:primary_key` option for `has_many` associations.
    Fixes #10693.

    *Yves Senn*

*   fixes bug introduced by #3329.  Now, when autosaving associations,
    deletions happen before inserts and saves.  This prevents a 'duplicate
    unique value' database error that would occur if a record being created had
    the same value on a unique indexed field as that of a record being destroyed.

    Backport of #10417

    *Johnny Holton*

*   Fix that under some conditions, Active Record could produce invalid SQL of the sort:
    "SELECT DISTINCT DISTINCT".

    Backport of #6792.

    *Ben Woosley*

*   Require `ActiveRecord::Base` in railtie hooks for rake_tasks, console and runner to
    avoid circular constant loading issues.

    Backport #7695.

    Fixes #7683 and #882

    *Ben Holley*

*   Maintain context for joins within ActiveRecord::Relation merges.
    Backport #10164.

    *Neeraj Singh + Andrew Horner*

*   Make sure the `EXPLAIN` command is never triggered by a `select_db` call.

    *Daniel Schierbeck*

*   Revert changes on `pluck` that was ignoring the select clause when the relation already
    has one. This caused a regression since it changed the behavior in a stable release.

    Fixes #9777.

    *Rafael Mendonça França*

*   Confirm a record has not already been destroyed before decrementing counter cache.

    *Ben Tucker*

*   Default values for PostgreSQL bigint types now get parsed and dumped to the
    schema correctly.
    Backport #10098.

    *Erik Peterson*

*   Removed warning when `auto_explain_threshold_in_seconds` is set and the
    connection adapter doesn't support explain.
    This is causing a regression since the Active Record Railtie is trying to
    connect to the development database in the application boot.

    *Rafael Mendonça França*

*   Do not reset `inheritance_column` when it's set explicitly.
    Backport of #5327.

    *kennyj + Fred Wu*

*   Fix a problem wrong exception is occured
    when raising no translatable exception in PostgreSQL.

    *kennyj*

*   Resets the postgres search path in the structure.sql after the structure
    is dumped in order to find schema_migrations table when multiples schemas
    are used.
    Fixes #9796.

    *Juan M. Cuello + Dembskiy Alexander*

*   Reload the association target if it's stale. `@stale_state` should be nil
    when a model isn't saved.
    Fixes #7526.

    *Larry Lv*

*   Don't read CSV files during execution of `db:fixtures:load`. CSV support for
    fixtures was removed some time ago but the task was still loading them, even
    though later the code was looking for the related yaml file instead.

    *kennyj*


## Rails 3.2.13 (Mar 18, 2013) ##

*   Chaining multiple preloaded scopes will correctly preload all the scopes
    at the same time.

    *Chris Geihsler*

*   Reverted 921a296a3390192a71abeec6d9a035cc6d1865c8, 'Quote numeric values
    compared to string columns.' This caused several regressions.

    *Steve Klabnik*

*   Fix overriding of attributes by `default_scope` on `ActiveRecord::Base#dup`.

    *Hiroshige UMINO*

*   Fix issue with overriding Active Record reader methods with a composed object
    and using that attribute as the scope of a `uniqueness_of` validation.
    Backport #7072.

    *Peter Brown*

*   Sqlite now preserves custom primary keys when copying or altering tables.
    Fixes #9367.
    Backport #2312.

    *Sean Scally + Yves Senn*

*   Preloading `has_many :through` associations with conditions won't
    cache the `:through` association. This will prevent invalid
    subsets to be cached.
    Fixes #8423.
    Backport #9252.

    Example:

        class User
          has_many :posts
          has_many :recent_comments, -> { where('created_at > ?', 1.week.ago) }, :through => :posts
        end

        a_user = User.includes(:recent_comments).first

        # this is preloaded
        a_user.recent_comments

        # fetching the recent_comments through the posts association won't preload it.
        a_user.posts

    *Yves Senn*

*   Fix handling of dirty time zone aware attributes

    Previously, when `time_zone_aware_attributes` were enabled, after
    changing a datetime or timestamp attribute and then changing it back
    to the original value, `changed_attributes` still tracked the
    attribute as changed. This caused `[attribute]_changed?` and
    `changed?` methods to return true incorrectly.

    Example:

        in_time_zone 'Paris' do
          order = Order.new
          original_time = Time.local(2012, 10, 10)
          order.shipped_at = original_time
          order.save
          order.changed? # => false

          # changing value
          order.shipped_at = Time.local(2013, 1, 1)
          order.changed? # => true

          # reverting to original value
          order.shipped_at = original_time
          order.changed? # => false, used to return true
        end

    Backport of #9073
    Fixes #8898

    *Lilibeth De La Cruz*

*   Fix counter cache columns not updated when replacing `has_many :through`
    associations.
    Backport #8400.
    Fix #7630.

    *Matthew Robertson*

*   Don't update `column_defaults` when calling destructive methods on column with default value.
    Backport c517602.
    Fix #6115.

    *Piotr Sarnacki + Aleksey Magusev + Alan Daud*

*   When `#count` is used in conjunction with `#uniq` we perform `count(:distinct => true)`.
    Fix #6865.

    Example:

      relation.uniq.count # => SELECT COUNT(DISTINCT *)

    *Yves Senn + Kaspar Schiess*

*   Fix `ActiveRecord::Relation#pluck` when columns or tables are reserved words.
    Backport #7536.
    Fix #8968.

    *Ian Lesperance + Yves Senn + Kaspar Schiess*

*   Don't run explain on slow queries for database adapters that don't support it.
    Backport #6197.

    *Blake Smith*

*   Revert round usec when comparing timestamp attributes in the dirty tracking.
    Fixes #8460.

    *Andrew White*

*   Revert creation of through association models when using `collection=[]`
    on a `has_many :through` association from an unsaved model.
    Fix #7661, #8269.

    *Ernie Miller*

*   Fix undefined method `to_i` when calling `new` on a scope that uses an
    Array; Fix FloatDomainError when setting integer column to NaN.
    Fixes #8718, #8734, #8757.

    *Jason Stirk + Tristan Harward*

*   Serialized attributes can be serialized in integer columns.
    Fix #8575.

    *Rafael Mendonça França*

*   Keep index names when using `alter_table` with sqlite3.
    Fix #3489.
    Backport #8522.

    *Yves Senn*

*   Recognize migrations placed in directories containing numbers and 'rb'.
    Fix #8492.
    Backport of #8500.

    *Yves Senn*

*   Add `ActiveRecord::Base.cache_timestamp_format` class attribute to control
    the format of the timestamp value in the cache key.
    This allows users to improve the precision of the cache key.
    Fixes #8195.

    *Rafael Mendonça França*

*   Add `:nsec` date format. This can be used to improve the precision of cache key.
    Please note that this format only works with Ruby 1.9, Ruby 1.8 will ignore it completely.

    *Jamie Gaskins*

*   Unscope `update_column(s)` query to ignore default scope.

    When applying `default_scope` to a class with a where clause, using
    `update_column(s)` could generate a query that would not properly update
    the record due to the where clause from the `default_scope` being applied
    to the update query.

        class User < ActiveRecord::Base
          default_scope where(active: true)
        end

        user = User.first
        user.active = false
        user.save!

        user.update_column(:active, true) # => false

    In this situation we want to skip the default_scope clause and just
    update the record based on the primary key. With this change:

        user.update_column(:active, true) # => true

    Backport of #8436 fix.

    *Carlos Antonio da Silva*

*   Fix performance problem with primary_key method in PostgreSQL adapter when having many schemas.
    Uses pg_constraint table instead of pg_depend table which has many records in general.
    Fix #8414

    *kennyj*

*   Do not instantiate intermediate Active Record objects when eager loading.
    These records caused `after_find` to run more than expected.
    Fix #3313
    Backport of #8403

    *Yves Senn*

*   Fix `pluck` to work with joins. Backport of #4942.

    *Carlos Antonio da Silva*

*   Fix a problem with `translate_exception` method in a non English environment.
    Backport of #6397.

    *kennyj*

*   Fix dirty attribute checks for TimeZoneConversion with nil and blank
    datetime attributes. Setting a nil datetime to a blank string should not
    result in a change being flagged.
    Fixes #8310.
    Backport of #8311.

    *Alisdair McDiarmid*

*   Prevent mass assignment to the type column of polymorphic associations when using `build`.
    Fixes #8265.
    Backport of #8291.

    *Yves Senn*

*   When running migrations on Postgresql, the `:limit` option for `binary` and `text` columns is
    silently dropped.
    Previously, these migrations caused sql exceptions, because Postgresql doesn't support limits
    on these types.

    *Victor Costan*

*   `#pluck` can be used on a relation with `select` clause.
    Fixes #7551.
    Backport of #8176.

    Example:

        Topic.select([:approved, :id]).order(:id).pluck(:id)

    *Yves Senn*

*   Use `nil?` instead of `blank?` to check whether dynamic finder with a bang
    should raise RecordNotFound.
    Fixes #7238.

    *Nikita Afanasenko*

*   Fix deleting from a HABTM join table upon destroying an object of a model
    with optimistic locking enabled.
    Fixes #5332.

    *Nick Rogers*

*   Use query cache/uncache when using ENV["DATABASE_URL"].
    Fixes #6951.
    Backport of #8074.

    *kennyj*

*   Do not create useless database transaction when building `has_one` association.

    Example:

        User.has_one :profile
        User.new.build_profile

    Backport of #8154.

    *Bogdan Gusiev*

*   `AR::Base#attributes_before_type_cast` now returns unserialized values for serialized attributes.

    *Nikita Afanasenko*

*   Fix issue that raises `NameError` when overriding the `accepts_nested_attributes` in child classes.

    Before:

        class Shared::Person < ActiveRecord::Base
          has_one :address

          accepts_nested_attributes :address, :reject_if => :all_blank
        end

        class Person < Shared::Person
          accepts_nested_attributes :address
        end

        Person
        #=> NameError: method `address_attributes=' not defined in Person

    After:

        Person
        #=> Person(id: integer, ...)

    Fixes #8131.

    *Gabriel Sobrinho, Ricardo Henrique*


## Rails 3.2.12 (Feb 11, 2013) ##

*   Quote numeric values being compared to non-numeric columns. Otherwise,
    in some database, the string column values will be coerced to a numeric
    allowing 0, 0.0 or false to match any string starting with a non-digit.

    Example:

        App.where(apikey: 0) # => SELECT * FROM users WHERE apikey = '0'

    *Dylan Smith*


## Rails 3.2.11 (Jan 8, 2013) ##

*   Fix querying with an empty hash *Damien Mathieu* [CVE-2013-0155]


## Rails 3.2.10 (Jan 2, 2013) ##

*   CVE-2012-5664 options hashes should only be extracted if there are extra
    parameters


## Rails 3.2.9 (Nov 12, 2012) ##

*   Fix `find_in_batches` crashing when IDs are strings and start option is not specified.

    *Alexis Bernard*

*   Fix issue with collection associations calling first(n)/last(n) and attempting
    to set the inverse association when `:inverse_of` was used. Fixes #8087.

    *Carlos Antonio da Silva*

*   Fix bug when Column is trying to type cast boolean values to integer.
    Fixes #8067.

    *Rafael Mendonça França*

*   Fix bug where `rake db:test:prepare` tries to load the structure.sql into development database.
    Fixes #8032.

    *Grace Liu + Rafael Mendonça França*

*   Fixed support for `DATABASE_URL` environment variable for rake db tasks. *Grace Liu*

*   Fix bug where `update_columns` and `update_column` would not let you update the primary key column.

    *Henrik Nyh*

*   Decode URI encoded attributes on database connection URLs.

    *Shawn Veader*

*   Fix AR#dup to nullify the validation errors in the dup'ed object. Previously the original
    and the dup'ed object shared the same errors.

    *Christian Seiler*

*   Synchronize around deleting from the reserved connections hash.
    Fixes #7955

*   PostgreSQL adapter correctly fetches default values when using
    multiple schemas and domains in a db. Fixes #7914

    *Arturo Pie*

*   Fix deprecation notice when loading a collection association that
    selects columns from other tables, if a new record was previously
    built using that association.

    *Ernie Miller*

*   The postgres adapter now supports tables with capital letters.
    Fix #5920

    *Yves Senn*

*   `CollectionAssociation#count` returns `0` without querying if the
    parent record is not persisted.

    Before:

        person.pets.count
        # SELECT COUNT(*) FROM "pets" WHERE "pets"."person_id" IS NULL
        # => 0

    After:

        person.pets.count
        # fires without sql query
        # => 0

    *Francesco Rodriguez*

*   Fix `reset_counters` crashing on `has_many :through` associations.
    Fix #7822.

    *lulalala*

*   ConnectionPool recognizes checkout_timeout spec key as taking
    precedence over legacy wait_timeout spec key, can be used to avoid
    conflict with mysql2 use of wait_timeout.  Closes #7684.

    *jrochkind*

*   Rename field_changed? to _field_changed? so that users can create a field named field

    *Akira Matsuda*, backported by *Steve Klabnik*

*   Fix creation of through association models when using `collection=[]`
    on a `has_many :through` association from an unsaved model.
    Fix #7661.

    *Ernie Miller*

*   Explain only normal CRUD sql (select / update / insert / delete).
    Fix problem that explains unexplainable sql. Closes #7544 #6458.

    *kennyj*

*   Backport test coverage to ensure that PostgreSQL auto-reconnect functionality
    remains healthy.

    *Steve Jorgensen*

*   Use config['encoding'] instead of config['charset'] when executing
    databases.rake in the mysql/mysql2. A correct option for a database.yml
    is 'encoding'.

    *kennyj*

*   Fix ConnectionAdapters::Column.type_cast_code integer conversion,
    to always convert values to integer calling #to_i. Fixes #7509.

    *Thiago Pradi*

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

    *Adam Meehan*

*   Fix `becomes` when using a configured `inheritance_column`.

    *Yves Senn*

*   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*

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

    *kennyj*

*   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*

*   Fix `increment!`, `decrement!`, `toggle!` that was skipping callbacks.
    Fixes #7306.

    *Rafael Mendonça França*

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

    *Dave Yeu*

*   Remove unnecessary transaction when assigning has_one associations with a nil or equal value.
    Fix #7191.

    *kennyj*

*   Allow store to work with an empty column.
    Fix #4840.

    *Jeremy Walker*

*   Remove prepared statement from system query in postgresql adapter.
    Fix #5872.

    *Ivan Evtuhovich*

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

    *Seamus Abshere*


## 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.

    CVE-2012-2695

*   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


## Rails 3.2.3 (March 30, 2012) ##

*   Added find_or_create_by_{attribute}! dynamic method. *Andrew White*

*   Whitelist all attribute assignment by default. Change the default for newly generated applications to whitelist all attribute assignment.  Also update the generated model classes so users are reminded of the importance of attr_accessible. *NZKoz*

*   Update ActiveRecord::AttributeMethods#attribute_present? to return false for empty strings. *Jacobkg*

*   Fix associations when using per class databases. *larskanis*

*   Revert setting NOT NULL constraints in add_timestamps *fxn*

*   Fix mysql to use proper text types. Fixes #3931. *kennyj*

*   Fix #5069 - Protect foreign key from mass assignment through association builder. *byroot*


## Rails 3.2.2 (March 1, 2012) ##

*   No changes.


## Rails 3.2.1 (January 26, 2012) ##

*   The threshold for auto EXPLAIN is ignored if there's no logger. *fxn*

*   Call `to_s` on the value passed to `table_name=`, in particular symbols
    are supported (regression). *Sergey Nartimov*

*   Fix possible race condition when two threads try to define attribute
    methods for the same class. *Jon Leighton*


## Rails 3.2.0 (January 20, 2012) ##

*   Added a `with_lock` method to ActiveRecord objects, which starts
    a transaction, locks the object (pessimistically) and yields to the block.
    The method takes one (optional) parameter and passes it to `lock!`.

    Before:

        class Order < ActiveRecord::Base
          def cancel!
            transaction do
              lock!
              # ... cancelling logic
            end
          end
        end

    After:

        class Order < ActiveRecord::Base
          def cancel!
            with_lock do
              # ... cancelling logic
            end
          end
        end

    *Olek Janiszewski*

*   'on' and 'ON' boolean columns values are type casted to true
    *Santiago Pastorino*

*   Added ability to run migrations only for given scope, which allows
    to run migrations only from one engine (for example to revert changes
    from engine that you want to remove).

    Example:
      rake db:migrate SCOPE=blog

    *Piotr Sarnacki*

*   Migrations copied from engines are now scoped with engine's name,
    for example 01_create_posts.blog.rb. *Piotr Sarnacki*

*   Implements `AR::Base.silence_auto_explain`. This method allows the user to
    selectively disable automatic EXPLAINs within a block. *fxn*

*   Implements automatic EXPLAIN logging for slow queries.

    A new configuration parameter `config.active_record.auto_explain_threshold_in_seconds`
    determines what's to be considered a slow query. Setting that to `nil` disables
    this feature. Defaults are 0.5 in development mode, and `nil` in test and production
    modes.

    As of this writing there's support for SQLite, MySQL (mysql2 adapter), and
    PostgreSQL.

    *fxn*

*   Implemented ActiveRecord::Relation#pluck method

    Method returns Array of column value from table under ActiveRecord model

        Client.pluck(:id)

    *Bogdan Gusiev*

*   Automatic closure of connections in threads is deprecated.  For example
    the following code is deprecated:

    Thread.new { Post.find(1) }.join

    It should be changed to close the database connection at the end of
    the thread:

    Thread.new {
      Post.find(1)
      Post.connection.close
    }.join

    Only people who spawn threads in their application code need to worry
    about this change.

*   Deprecated:

      * `set_table_name`
      * `set_inheritance_column`
      * `set_sequence_name`
      * `set_primary_key`
      * `set_locking_column`

    Use an assignment method instead. For example, instead of `set_table_name`, use `self.table_name=`:

         class Project < ActiveRecord::Base
           self.table_name = "project"
         end

    Or define your own `self.table_name` method:

         class Post < ActiveRecord::Base
           def self.table_name
             "special_" + super
           end
         end
         Post.table_name # => "special_posts"

    *Jon Leighton*

*   Generated association methods are created within a separate module to allow overriding and
    composition using `super`. For a class named `MyModel`, the module is named
    `MyModel::GeneratedFeatureMethods`. It is included into the model class immediately after
    the `generated_attributes_methods` module defined in ActiveModel, so association methods
    override attribute methods of the same name. *Josh Susser*

*   Implemented ActiveRecord::Relation#explain. *fxn*

*   Add ActiveRecord::Relation#uniq for generating unique queries.

    Before:

        Client.select('DISTINCT name')

    After:

        Client.select(:name).uniq

    This also allows you to revert the unqueness in a relation:

        Client.select(:name).uniq.uniq(false)

    *Jon Leighton*

*   Support index sort order in sqlite, mysql and postgres adapters. *Vlad Jebelev*

*   Allow the :class_name option for associations to take a symbol (:Client) in addition to
    a string ('Client').

    This is to avoid confusing newbies, and to be consistent with the fact that other options
    like :foreign_key already allow a symbol or a string.

    *Jon Leighton*

*   In development mode the db:drop task also drops the test database. For symmetry with
    the db:create task. *Dmitriy Kiriyenko*

*   Added ActiveRecord::Base.store for declaring simple single-column key/value stores *DHH*

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

        u = User.new(color: 'black', homepage: '37signals.com')
        u.color                          # Accessor stored attribute
        u.settings[:country] = 'Denmark' # Any attribute, even if not specified with an accessor


*   MySQL: case-insensitive uniqueness validation avoids calling LOWER when
    the column already uses a case-insensitive collation. Fixes #561.

    *Joseph Palermo*

*   Transactional fixtures enlist all active database connections. You can test
    models on different connections without disabling transactional fixtures.

    *Jeremy Kemper*

*   Add first_or_create, first_or_create!, first_or_initialize methods to Active Record. This is a
    better approach over the old find_or_create_by dynamic methods because it's clearer which
    arguments are used to find the record and which are used to create it:

        User.where(:first_name => "Scarlett").first_or_create!(:last_name => "Johansson")

    *Andrés Mejía*

*   Fix nested attributes bug where _destroy parameter is taken into account
    during :reject_if => :all_blank (fixes #2937)

    *Aaron Christy*

*   Add ActiveSupport::Cache::NullStore for use in development and testing.

    *Brian Durand*

Please check [3-1-stable](https://github.com/rails/rails/blob/3-1-stable/activerecord/CHANGELOG.md) for previous changes.