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## Rails 4.0.0 (unreleased) ##
* Added `#none!` method for mutating `ActiveRecord::Relation` objects to a NullRelation.
It acts like `#none` but modifies relation in place.
*Juanjo Bazán*
* Fix bug where `update_columns` and `update_column` would not let you update the primary key column.
*Henrik Nyh*
* The `create_table` method raises an `ArgumentError` when the primary key column is redefined.
Fix #6378
*Yves Senn*
* `ActiveRecord::AttributeMethods#[]` raises `ActiveModel::MissingAttributeError`
error if the given attribute is missing. Fixes #5433.
class Person < ActiveRecord::Base
belongs_to :company
end
# Before:
person = Person.select('id').first
person[:name] # => nil
person.name # => ActiveModel::MissingAttributeError: missing_attribute: name
person[:company_id] # => nil
person.company # => nil
# After:
person = Person.select('id').first
person[:name] # => ActiveModel::MissingAttributeError: missing_attribute: name
person.name # => ActiveModel::MissingAttributeError: missing_attribute: name
person[:company_id] # => ActiveModel::MissingAttributeError: missing_attribute: company_id
person.company # => ActiveModel::MissingAttributeError: missing_attribute: company_id
*Francesco Rodriguez*
* Small binary fields use the `VARBINARY` MySQL type, instead of `TINYBLOB`.
*Victor Costan*
* Decode URI encoded attributes on database connection URLs.
*Shawn Veader*
* Add `find_or_create_by`, `find_or_create_by!` and
`find_or_initialize_by` methods to `Relation`.
These are similar to the `first_or_create` family of methods, but
the behaviour when a record is created is slightly different:
User.where(first_name: 'Penélope').first_or_create
will execute:
User.where(first_name: 'Penélope').create
Causing all the `create` callbacks to execute within the context of
the scope. This could affect queries that occur within callbacks.
User.find_or_create_by(first_name: 'Penélope')
will execute:
User.create(first_name: 'Penélope')
Which obviously does not affect the scoping of queries within
callbacks.
The `find_or_create_by` version also reads better, frankly.
If you need to add extra attributes during create, you can do one of:
User.create_with(active: true).find_or_create_by(first_name: 'Jon')
User.find_or_create_by(first_name: 'Jon') { |u| u.active = true }
The `first_or_create` family of methods have been nodoc'ed in favour
of this API. They may be deprecated in the future but their
implementation is very small and it's probably not worth putting users
through lots of annoying deprecation warnings.
*Jon Leighton*
* Fix bug with presence validation of associations. Would incorrectly add duplicated errors
when the association was blank. Bug introduced in 1fab518c6a75dac5773654646eb724a59741bc13.
*Scott Willson*
* Fix bug where sum(expression) returns string '0' for no matching records.
Fixes #7439
*Tim Macfarlane*
* PostgreSQL adapter correctly fetches default values when using multiple schemas and domains in a db. Fixes #7914
*Arturo Pie*
* Learn ActiveRecord::QueryMethods#order work with hash arguments
When symbol or hash passed we convert it to Arel::Nodes::Ordering.
If we pass invalid direction(like name: :DeSc) ActiveRecord::QueryMethods#order will raise an exception
User.order(:name, email: :desc)
# SELECT "users".* FROM "users" ORDER BY "users"."name" ASC, "users"."email" DESC
*Tima Maslyuchenko*
* Rename `ActiveRecord::Fixtures` class to `ActiveRecord::FixtureSet`.
Instances of this class normally hold a collection of fixtures (records)
loaded either from a single YAML file, or from a file and a folder
with the same name. This change make the class name singular and makes
the class easier to distinguish from the modules like
`ActiveRecord::TestFixtures`, which operates on multiple fixture sets,
or `DelegatingFixtures`, `::Fixtures`, etc.,
and from the class `ActiveRecord::Fixture`, which corresponds to a single
fixture.
*Alexey Muranov*
* 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*
* Support for partial inserts.
When inserting new records, only the fields which have been changed
from the defaults will actually be included in the INSERT statement.
The other fields will be populated by the database.
This is more efficient, and also means that it will be safe to
remove database columns without getting subsequent errors in running
app processes (so long as the code in those processes doesn't
contain any references to the removed column).
The `partial_updates` configuration option is now renamed to
`partial_writes` to reflect the fact that it now impacts both inserts
and updates.
*Jon Leighton*
* Allow before and after validations to take an array of lifecycle events
*John Foley*
* Support for specifying transaction isolation level
If your database supports setting the isolation level for a transaction, you can set
it like so:
Post.transaction(isolation: :serializable) do
# ...
end
Valid isolation levels are:
* `:read_uncommitted`
* `:read_committed`
* `:repeatable_read`
* `:serializable`
You should consult the documentation for your database to understand the
semantics of these different levels:
* http://www.postgresql.org/docs/9.1/static/transaction-iso.html
* https://dev.mysql.com/doc/refman/5.0/en/set-transaction.html
An `ActiveRecord::TransactionIsolationError` will be raised if:
* The adapter does not support setting the isolation level
* You are joining an existing open transaction
* You are creating a nested (savepoint) transaction
The mysql, mysql2 and postgresql adapters support setting the transaction
isolation level. However, support is disabled for mysql versions below 5,
because they are affected by a bug (http://bugs.mysql.com/bug.php?id=39170)
which means the isolation level gets persisted outside the transaction.
*Jon Leighton*
* `ActiveModel::ForbiddenAttributesProtection` is included by default
in Active Record models. Check the docs of `ActiveModel::ForbiddenAttributesProtection`
for more details.
*Guillermo Iguaran*
* Remove integration between Active Record and
`ActiveModel::MassAssignmentSecurity`, `protected_attributes` gem
should be added to use `attr_accessible`/`attr_protected`. Mass
assignment options has been removed from all the AR methods that
used it (ex. `AR::Base.new`, `AR::Base.create`, `AR::Base#update_attributes`, etc).
*Guillermo Iguaran*
* Fix the return of querying with an empty hash.
Fix #6971.
User.where(token: {})
Before:
#=> SELECT * FROM users;
After:
#=> SELECT * FROM users WHERE 1 = 2;
*Damien Mathieu*
* 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*
* You can now override the generated accessor methods for stored attributes
and reuse the original behavior with `read_store_attribute` and `write_store_attribute`,
which are counterparts to `read_attribute` and `write_attribute`.
*Matt Jones*
* Accept belongs_to (including polymorphic) association keys in queries.
The following queries are now equivalent:
Post.where(author: author)
Post.where(author_id: author)
PriceEstimate.where(estimate_of: treasure)
PriceEstimate.where(estimate_of_type: 'Treasure', estimate_of_id: treasure)
*Peter Brown*
* Use native `mysqldump` command instead of `structure_dump` method
when dumping the database structure to a sql file. Fixes #5547.
*kennyj*
* PostgreSQL inet and cidr types are converted to `IPAddr` objects.
*Dan McClain*
* PostgreSQL array type support. Any datatype can be used to create an
array column, with full migration and schema dumper support.
To declare an array column, use the following syntax:
create_table :table_with_arrays do |t|
t.integer :int_array, array: true
# integer[]
t.integer :int_array, array: true, length: 2
# smallint[]
t.string :string_array, array: true, length: 30
# char varying(30)[]
end
This respects any other migration detail (limits, defaults, etc).
Active Record will serialize and deserialize the array columns on
their way to and from the database.
One thing to note: PostgreSQL does not enforce any limits on the
number of elements, and any array can be multi-dimensional. Any
array that is multi-dimensional must be rectangular (each sub array
must have the same number of elements as its siblings).
If the `pg_array_parser` gem is available, it will be used when
parsing PostgreSQL's array representation.
*Dan McClain*
* Attribute predicate methods, such as `article.title?`, will now raise
`ActiveModel::MissingAttributeError` if the attribute being queried for
truthiness was not read from the database, instead of just returning `false`.
*Ernie Miller*
* `ActiveRecord::SchemaDumper` uses Ruby 1.9 style hash, which means that the
schema.rb file will be generated using this new syntax from now on.
*Konstantin Shabanov*
* Map interval with precision to string datatype in PostgreSQL. Fixes #7518.
*Yves Senn*
* Fix eagerly loading associations without primary keys. Fixes #4976.
*Kelley Reynolds*
* 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 calling `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 `README.md` 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.
*kennyj*
* 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 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*
* 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) }
end
end
class Post < ActiveRecord::Base
extend Commentable
has_many_comments -> { where(:bar) }
end
*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
end
*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.
Example:
@posts = Post.where(published: true).load
*Jon Leighton*
* `Relation#order`: make new order prepend old one.
User.order("name asc").order("created_at desc")
# SELECT * FROM users ORDER BY created_at desc, name asc
This also affects order defined in `default_scope` or any kind of associations.
*Bogdan Gusiev*
* `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*
* Added `#update_columns` method which updates the attributes from
the passed-in hash without calling save, hence skipping validations and
callbacks. `ActiveRecordError` will be raised when called on new objects
or when at least one of the attributes is marked as read only.
post.attributes # => {"id"=>2, "title"=>"My title", "body"=>"My content", "author"=>"Peter"}
post.update_columns(title: 'New title', author: 'Sebastian') # => true
post.attributes # => {"id"=>2, "title"=>"New title", "body"=>"My content", "author"=>"Sebastian"}
*Sebastian Martinez + Rafael Mendonça França*
* 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:
development:
adapter: postgresql
host: localhost
database: rails_development
username: foo
password: bar
encoding: UTF8
collation: ja_JP.UTF8
ctype: ja_JP.UTF8
*kennyj*
* 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
end
end
*Tony Schneider*
* Allow `ActiveRecord::Relation#pluck` to accept multiple columns. Returns an
array of arrays containing the typecasted values:
Person.pluck(:id, :name)
# SELECT people.id, people.name 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.
*kennyj*
* 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
end
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
`find_or_create_by(...)` or where(...).first_or_create`
* `find_or_create_by_...!` can be rewritten using
`find_or_create_by!(...) or `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
different 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: Time.now - 2.weeks)
Or a more subtle variant:
scope :recent, -> { where(published_at: Time.now - 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:
https://github.com/rails/rails/commit/302c912bf6bcd0fa200d964ec2dc4a44abe328a6
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
*kennyj*
* 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')
Generates
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).
*Aaron Paterson*
* In previous releases, the following would generate a single query with
an `OUTER JOIN comments`, rather than two separate queries:
Post.includes(:comments)
.where("comments.name = '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:
Post.includes(:comments)
.where("comments.name = 'foo'")
.references(:comments)
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('comments.name' => 'foo')
Post.order('comments.name')
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`.
*Aaron Patterson*
* Connections *must* be closed at the end of a thread. If not, your
connection pool can fill and an exception will be raised.
*Aaron Patterson*
* PostgreSQL hstore records can be created.
*Aaron Patterson*
* PostgreSQL hstore types are automatically deserialized from the database.
*Aaron Patterson*
Please check [3-2-stable](https://github.com/rails/rails/blob/3-2-stable/activerecord/CHANGELOG.md) for previous changes.
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