rails/activerecord/CHANGELOG.md

• Add the ability to nullify the enum column.

  Example:

   class Conversation < ActiveRecord::Base
     enum gender: [:female, :male]
   end
  
   Conversation::GENDER # => { female: 0, male: 1 }
  
   # conversation.update! gender: 0
   conversation.female!
   conversation.female? # => true
   conversation.gender  # => "female"
  
   # conversation.update! gender: nil
   conversation.gender = nil
   conversation.gender.nil? # => true
   conversation.gender      # => nil
  

  Amr Tamimi

• Connection specification now accepts a "url" key. The value of this key is expected to contain a database URL. The database URL will be expanded into a hash and merged.

  Richard Schneeman

• An ArgumentError is now raised on a call to Relation#where.not(nil).

  Example:

  User.where.not(nil)
  
  # Before
  # => 'SELECT `users`.* FROM `users`  WHERE (NOT (NULL))'
  
  # After
  # => ArgumentError, 'Invalid argument for .where.not(), got nil.'
  

  Kuldeep Aggarwal

• Deprecated use of string argument as a configuration lookup in ActiveRecord::Base.establish_connection. Instead, a symbol must be given.

  José Valim

• Fixed update_column, update_columns, and update_all to correctly serialize values for array, hstore and json column types in PostgreSQL.

  Fixes #12261.

  Tadas Tamosauskas, Carlos Antonio da Silva

• Do not consider PostgreSQL array columns as number or text columns.

  The code uses these checks in several places to know what to do with a particular column, for instance AR attribute query methods has a branch like this:

  if column.number?
    !value.zero?
  end
  

  This should never be true for array columns, since it would be the same as running [].zero?, which results in a NoMethodError exception.

  Fixing this by ensuring that array columns in PostgreSQL never return true for number?/text? checks.

  Carlos Antonio da Silva

• When connecting to a non-existant database, the error: ActiveRecord::NoDatabaseError will now be raised. When being used with Rails the error message will include information on how to create a database: rake db:create. Supported adapters: postgresql, mysql, mysql2, sqlite3

  Richard Schneeman

• Do not raise 'can not touch on a new record object' exception on destroying already destroyed belongs_to association with touch: true option.

  Fixes #13445.

  Example:

  # Given Comment has belongs_to :post, touch: true
  comment.post.destroy
  comment.destroy # no longer raises an error
  

  Paul Nikitochkin

• Fix a bug when assigning an array containing string numbers to a PostgreSQL integer array column.

  Fixes #13444.

  Example:

  # Given Book#ratings is of type :integer, array: true
  Book.new(ratings: [1, 2]) # worked before
  Book.new(ratings: ['1', '2']) # now works as well
  

  Damien Mathieu

• Improve the default select when from is used.

  Previously, if you did something like Topic.from(:temp_topics), it would generate SQL like:

  SELECT topics.* FROM temp_topics;
  

  Which is will cause an error since there's not a topics table to select from.

  Now the default if you use from is just *:

  SELECT * FROM temp_topics;
  

  Cody Cutrer

• Fix PostgreSQL insert to properly extract table name from multiline string SQL.

  Previously, executing an insert SQL in PostgreSQL with a command like this:

  insert into articles(
    number)
  values(
    5152
  )
  

  would not work because the adapter was unable to extract the correct articles table name.

  Kuldeep Aggarwal

• Relation no longer has mutator methods like #map! and #delete_if. Convert to an Array by calling #to_a before using these methods.

  It intends to prevent odd bugs and confusion in code that call mutator methods directly on the Relation.

  Example:

  # Instead of this
  Author.where(name: 'Hank Moody').compact!
  
  # Now you have to do this
  authors = Author.where(name: 'Hank Moody').to_a
  authors.compact!
  

  Lauro Caetano

• Better support for where() conditions that use a belongs_to association name.

  Using the name of an association in where previously worked only if the value was a single ActiveRecord::Base object. e.g.

  Post.where(author: Author.first)
  

  Any other values, including nil, would cause invalid SQL to be generated. This change supports arguments in the where query conditions where the key is a belongs_to association name and the value is nil, an Array of ActiveRecord::Base objects, or an ActiveRecord::Relation object.

  class Post < ActiveRecord::Base
    belongs_to :author
  end
  

  nil value finds records where the association is not set:

  Post.where(author: nil)
  # SELECT "posts".* FROM "posts" WHERE "posts"."author_id" IS NULL
  

  Array values find records where the association foreign key matches the ids of the passed ActiveRecord models, resulting in the same query as Post.where(author_id: [1,2]):

  authors_array = [Author.find(1), Author.find(2)]
  Post.where(author: authors_array)
  # SELECT "posts".* FROM "posts" WHERE "posts"."author_id" IN (1, 2)
  

  ActiveRecord::Relation values find records using the same query as Post.where(author_id: Author.where(last_name: "Emde"))

  Post.where(author: Author.where(last_name: "Emde"))
  # SELECT "posts".* FROM "posts"
  # WHERE "posts"."author_id" IN (
  #   SELECT "authors"."id" FROM "authors"
  #   WHERE "authors"."last_name" = 'Emde')
  

  Polymorphic belongs_to associations will continue to be handled appropriately, with the polymorphic association_type field added to the query to match the base class of the value. This feature previously only worked when the value was a single ActveRecord::Base.

  class Post < ActiveRecord::Base
    belongs_to :author, polymorphic: true
  end
  
  Post.where(author: Author.where(last_name: "Emde"))
  # Generates a query similar to:
  Post.where(author_id: Author.where(last_name: "Emde"), author_type: "Author")
  

  Martin Emde

• Respect temporary option when dropping tables with MySQL.

  Normal DROP TABLE also works, but commits the transaction.

  drop_table :temporary_table, temporary: true
  

  Cody Cutrer

• Add option to create tables from a query.

  create_table(:long_query, temporary: true,
    as: "SELECT * FROM orders INNER JOIN line_items ON order_id=orders.id")
  

  Generates:

  CREATE TEMPORARY TABLE long_query AS
    SELECT * FROM orders INNER JOIN line_items ON order_id=orders.id
  

  Cody Cutrer

• db:test:clone and db:test:prepare must load Rails environment.

  db:test:clone and db:test:prepare use ActiveRecord::Base. configurations, so we need to load the Rails environment, otherwise the config wont be in place.

  arthurnn

• Use the right column to type cast grouped calculations with custom expressions.

  Fixes #13230.

  Example:

  # Before
  Account.group(:firm_name).sum('0.01 * credit_limit')
  # => { '37signals' => '0.5' }
  
  # After
  Account.group(:firm_name).sum('0.01 * credit_limit')
  # => { '37signals' => 0.5 }
  

  Paul Nikitochkin

• Polymorphic belongs_to associations with the touch: true option set update the timestamps of the old and new owner correctly when moved between owners of different types.

  Example:

  class Rating < ActiveRecord::Base
    belongs_to :rateable, polymorphic: true, touch: true
  end
  
  rating = Rating.create rateable: Song.find(1)
  rating.update_attributes rateable: Book.find(2) # => timestamps of Song(1) and Book(2) are updated
  

  Severin Schoepke

• Improve formatting of migration exception messages: make them easier to read with line breaks before/after, and improve the error for pending migrations.

  John Bachir

• Fix last with offset to return the proper record instead of always the last one.

  Example:

  Model.offset(4).last
  # => returns the 4th record from the end.
  

  Fixes #7441.

  kostya, Lauro Caetano

• type_to_sql returns a String for unmapped columns. This fixes an error when using unmapped array types in PG

  Example:

  change_colum :table, :column, :bigint, array: true
  

  Fixes #13146.

  Jens Fahnenbruck, Yves Senn

• Fix QueryCache to work with nested blocks, so that it will only clear the existing cache after leaving the outer block instead of clearing it right after the inner block is finished.

  Vipul A M

• The ERB in fixture files is no longer evaluated in the context of the main object. Helper methods used by multiple fixtures should be defined on the class object returned by ActiveRecord::FixtureSet.context_class.

  Victor Costan

• Previously, the has_one macro incorrectly accepted the counter_cache option, but never actually supported it. Now it will raise an ArgumentError when using has_one with counter_cache.

  Godfrey Chan

• Implement rename_index natively for MySQL >= 5.7.

  Cody Cutrer

• Fix bug when validating the uniqueness of an aliased attribute.

  Fixes #12402.

  Lauro Caetano

• Update counter cache on a has_many relationship regardless of default scope.

  Fix #12952.

  Uku Taht

• rename_index adds the new index before removing the old one. This allows to rename indexes on columns with a foreign key and prevents the following error:

  Cannot drop index 'index_engines_on_car_id': needed in a foreign key constraint
  

  Cody Cutrer, Yves Senn

• Raise ActiveRecord::RecordNotDestroyed when a replaced child marked with dependent: destroy fails to be destroyed.

  Fix #12812

  Brian Thomas Storti

• Fix validation on uniqueness of empty association.

  Evgeny Li

• Make ActiveRecord::Relation#unscope affect relations it is merged in to.

  Jon Leighton

• Use strings to represent non-string order_values.

  Yves Senn

• Checks to see if the record contains the foreign key to set the inverse automatically.

  Edo Balvers

• Added ActiveRecord::Base.to_param for convenient "pretty" URLs derived from a model's attribute or method.

  Example:

  class User < ActiveRecord::Base
    to_param :name
  end
  
  user = User.find_by(name: 'Fancy Pants')
  user.id       # => 123
  user.to_param # => "123-fancy-pants"
  

  Javan Makhmali

• Added ActiveRecord::Base.no_touching, which allows ignoring touch on models.

  Example:

  Post.no_touching do
    Post.first.touch
  end
  

  Sam Stephenson, Damien Mathieu

• Prevent the counter cache from being decremented twice when destroying a record on a has_many :through association.

  Fixes #11079.

  Dmitry Dedov

• Unify boolean type casting for MysqlAdapter and Mysql2Adapter. type_cast will return 1 for true and 0 for false.

  Fixes #11119.

  Adam Williams, Yves Senn

• Fix bug where has_one association record update result in crash, when replaced with itself.

  Fixes #12834.

  Denis Redozubov, Sergio Cambra

• Log bind variables after they are type casted. This makes it more transparent what values are actually sent to the database.

  irb(main):002:0> Event.find("im-no-integer")
  # Before: ... WHERE "events"."id" = $1 LIMIT 1  [["id", "im-no-integer"]]
  # After: ... WHERE "events"."id" = $1 LIMIT 1  [["id", 0]]
  

  Yves Senn

• Fix uninitialized constant TransactionState error when Marshall.load is used on an Active Record result.

  Fixes #12790.

  Jason Ayre

• .unscope now removes conditions specified in default_scope.

  Jon Leighton

• Added ActiveRecord::QueryMethods#rewhere which will overwrite an existing, named where condition.

  Examples:

  Post.where(trashed: true).where(trashed: false)                       #=> WHERE `trashed` = 1 AND `trashed` = 0
  Post.where(trashed: true).rewhere(trashed: false)                     #=> WHERE `trashed` = 0
  Post.where(active: true).where(trashed: true).rewhere(trashed: false) #=> WHERE `active` = 1 AND `trashed` = 0
  

  DHH

• Extend ActiveRecord::Base#cache_key to take an optional list of timestamp attributes of which the highest will be used.

  Example:

  # last_reviewed_at will be used, if that's more recent than updated_at, or vice versa
  Person.find(5).cache_key(:updated_at, :last_reviewed_at)
  

  DHH

• Added ActiveRecord::Base#enum for declaring enum attributes where the values map to integers in the database, but can be queried by name.

  Example:

  class Conversation < ActiveRecord::Base
    enum status: [:active, :archived]
  end
  
  Conversation::STATUS # => { active: 0, archived: 1 }
  
  # conversation.update! status: 0
  conversation.active!
  conversation.active? # => true
  conversation.status  # => "active"
  
  # conversation.update! status: 1
  conversation.archived!
  conversation.archived? # => true
  conversation.status    # => "archived"
  
  # conversation.update! status: 1
  conversation.status = :archived
  

  DHH

• ActiveRecord::Base#attribute_for_inspect now truncates long arrays (more than 10 elements).

  Jan Bernacki

• Allow for the name of the schema_migrations table to be configured.

  Jerad Phelps

• Do not add to scope includes values from through associations. Fixed bug when providing includes in through association scope, and fetching targets.

  Example:

  class Vendor < ActiveRecord::Base
    has_many :relationships, -> { includes(:user) }
    has_many :users, through: :relationships
  end
  
  vendor = Vendor.first
  
  # Before
  
  vendor.users.to_a # => Raises exception: not found `:user` for `User`
  
  # After
  
  vendor.users.to_a # => No exception is raised
  

  Fixes #12242, #9517, #10240.

  Paul Nikitochkin

• Type cast json values on write, so that the value is consistent with reading from the database.

  Example:

  x = JsonDataType.new tags: {"string" => "foo", :symbol => :bar}
  
  # Before:
  x.tags # => {"string" => "foo", :symbol => :bar}
  
  # After:
  x.tags # => {"string" => "foo", "symbol" => "bar"}
  

  Severin Schoepke

• ActiveRecord::Store works together with PG hstore columns.

  Fixes #12452.

  Yves Senn

• Fix bug where ActiveRecord::Store used a global Hash to keep track of all registered stored_attributes. Now every subclass of ActiveRecord::Base has it's own Hash.

  Yves Senn

• Save has_one association when primary key is manually set.

  Fixes #12302.

  Lauro Caetano

• Allow any version of BCrypt when using has_secure_password.

  Mike Perham

• Sub-query generated for Relation passed as array condition did not take in account bind values and have invalid syntax.

  Generate sub-query with inline bind values.

  Fixes #12586.

  Paul Nikitochkin

• Fix a bug where rake db:structure:load crashed when the path contained spaces.

  Kevin Mook

• ActiveRecord::QueryMethods#unscope unscopes negative equality

  Allows you to call #unscope on a relation with negative equality operators, i.e. Arel::Nodes::NotIn and Arel::Nodes::NotEqual that have been generated through the use of where.not.

  Eric Hankins

• Raise an exception when model without primary key calls .find_with_ids.

  Shimpei Makimoto

• Make Relation#empty? use exists? instead of count.

  Szymon Nowak

• rake db:structure:dump no longer crashes when the port was specified as Fixnum.

  Kenta Okamoto

• NullRelation#pluck takes a list of columns

  The method signature in NullRelation was updated to mimic that in Calculations.

  Derek Prior

• scope_chain should not be mutated for other reflections.

  Currently scope_chain uses same array for building different scope_chain for different associations. During processing these arrays are sometimes mutated and because of in-place mutation the changed scope_chain impacts other reflections.

  Fix is to dup the value before adding to the scope_chain.

  Fixes #3882.

  Neeraj Singh

• Prevent the inversed association from being reloaded on save.

  Fixes #9499.

  Dmitry Polushkin

• Generate subquery for Relation if it passed as array condition for where method.

  Example:

  # Before
  Blog.where('id in (?)', Blog.where(id: 1))
  # =>  SELECT "blogs".* FROM "blogs"  WHERE "blogs"."id" = 1
  # =>  SELECT "blogs".* FROM "blogs"  WHERE (id IN (1))
  
  # After
  Blog.where('id in (?)', Blog.where(id: 1).select(:id))
  # =>  SELECT "blogs".* FROM "blogs"
  #     WHERE "blogs"."id" IN (SELECT "blogs"."id" FROM "blogs"  WHERE "blogs"."id" = 1)
  

  Fixes #12415.

  Paul Nikitochkin

• For missed association exception message which is raised in ActiveRecord::Associations::Preloader class added owner record class name in order to simplify to find problem code.

  Paul Nikitochkin

• has_and_belongs_to_many is now transparently implemented in terms of has_many :through. Behavior should remain the same, if not, it is a bug.

• create_savepoint, rollback_to_savepoint and release_savepoint accept a savepoint name.

  Yves Senn

• Make next_migration_number accessible for third party generators.

  Yves Senn

• Objects instantiated using a null relationship will now retain the attributes of the where clause.

  Fixes #11676, #11675, #11376.

  Paul Nikitochkin, Peter Brown, Nthalk

• Fixed ActiveRecord::Associations::CollectionAssociation#find when using has_many association with :inverse_of and finding an array of one element, it should return an array of one element too.

  arthurnn

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

  arthurnn

• ActiveRecord::ConnectionAdapters.string_to_time respects string with timezone (e.g. Wed, 04 Sep 2013 20:30:00 JST).

  Fixes #12278.

  kennyj

• Calling update_attributes will now throw an ArgumentError whenever it gets a nil argument. More specifically, it will throw an error if the argument that it gets passed does not respond to to stringify_keys.

  Example:

  @my_comment.update_attributes(nil)  # => raises ArgumentError
  

  John Wang

• Deprecate quoted_locking_column method, which isn't used anywhere.

  kennyj

• Migration dump UUID default functions to schema.rb.

  Fixes #10751.

  kennyj

• Fixed a bug in ActiveRecord::Associations::CollectionAssociation#find_by_scan when using has_many association with :inverse_of option and UUID primary key.

  Fixes #10450.

  kennyj

• Fix: joins association, with defined in the scope block constraints by using several where constraints and at least of them is not Arel::Nodes::Equality, generates invalid SQL expression.

  Fixes #11963.

  Paul Nikitochkin

• CollectionAssociation#first/#last (e.g. has_many) use a LIMITed query to fetch results rather than loading the entire collection.

  Lann Martin

• Make possible to run SQLite rake tasks without the Rails constant defined.

  Damien Mathieu

• Allow Relation#from to accept other relations with bind values.

  Ryan Wallace

• Fix inserts with prepared statements disabled.

  Fixes #12023.

  Rafael Mendonça França

• Setting a has_one association on a new record no longer causes an empty transaction.

  Dylan Thacker-Smith

• Fix AR::Relation#merge sometimes failing to preserve readonly(false) flag.

  thedarkone

• Re-use order argument pre-processing for reorder.

  Paul Nikitochkin

• Fix PredicateBuilder so polymorphic association keys in where clause can accept objects other than direct descendants of ActiveRecord::Base (decorated models, for example).

  Mikhail Dieterle

• PostgreSQL adapter recognizes negative money values formatted with parentheses (eg. ($1.25) # => -1.25)). Fixes #11899.

  Yves Senn

• Stop interpreting SQL 'string' columns as :string type because there is no common STRING datatype in SQL.

  Ben Woosley

• ActiveRecord::FinderMethods#exists? returns true/false in all cases.

  Xavier Noria

• Assign inet/cidr attribute with nil value for invalid address.

  Example:

  record = User.new
  record.logged_in_from_ip # is type of an inet or a cidr
  
  # Before:
  record.logged_in_from_ip = 'bad ip address' # raise exception
  
  # After:
  record.logged_in_from_ip = 'bad ip address' # do not raise exception
  record.logged_in_from_ip # => nil
  record.logged_in_from_ip_before_type_cast # => 'bad ip address'
  

  Paul Nikitochkin

• add_to_target now accepts a second optional skip_callbacks argument

  If truthy, it will skip the :before_add and :after_add callbacks.

  Ben Woosley

• Fix interactions between :before_add callbacks and nested attributes assignment of has_many associations, when the association was not yet loaded:

  • A :before_add callback was being called when a nested attributes assignment assigned to an existing record.

  • Nested Attributes assignment did not affect the record in the association target when a :before_add callback triggered the loading of the association

  Jörg Schray

• Allow enable_extension migration method to be revertible.

  Eric Tipton

• Type cast hstore values on write, so that the value is consistent with reading from the database.

  Example:

  x = Hstore.new tags: {"bool" => true, "number" => 5}
  
  # Before:
  x.tags # => {"bool" => true, "number" => 5}
  
  # After:
  x.tags # => {"bool" => "true", "number" => "5"}
  

  Yves Senn , Severin Schoepke

• Fix multidimensional PG arrays containing non-string items.

  Yves Senn

• Fixes bug when using includes combined with select, the select statement was overwritten.

  Fixes #11773.

  Edo Balvers

• Load fixtures from linked folders.

  Kassio Borges

• Create a directory for sqlite3 file if not present on the system.

  Richard Schneeman

• Removed redundant override of xml column definition for PG, in order to use xml column type instead of text.

  Paul Nikitochkin, Michael Nikitochkin

• Revert ActiveRecord::Relation#order change that make new order prepend the old one.

  Before:

  User.order("name asc").order("created_at desc")
  # SELECT * FROM users ORDER BY created_at desc, name asc
  

  After:

  User.order("name asc").order("created_at desc")
  # SELECT * FROM users ORDER BY name asc, created_at desc
  

  This also affects order defined in default_scope or any kind of associations.

• Add ability to define how a class is converted to Arel predicates. For example, adding a very vendor specific regex implementation:

  regex_handler = proc do |column, value|
    Arel::Nodes::InfixOperation.new('~', column, value.source)
  end
  ActiveRecord::PredicateBuilder.register_handler(Regexp, regex_handler)
  

  Sean Griffin & @joannecheng

• Don't allow quote_value to be called without a column.

  Some adapters require column information to do their job properly. By enforcing the provision of the column for this internal method we ensure that those using adapters that require column information will always get the proper behavior.

  Ben Woosley

• 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 column types.

  Fixes #6763.

  Alfred Wong

• rescue from all exceptions in ConnectionManagement#call

  Fixes #11497.

  As ActiveRecord::ConnectionAdapters::ConnectionManagement middleware does not rescue from Exception (but only from StandardError), the Connection Pool quickly runs out of connections when multiple erroneous Requests come in right after each other.

  Rescuing from all exceptions and not just StandardError, fixes this behaviour.

  Vipul A M

• change_column for PostgreSQL adapter respects the :array option.

  Yves Senn

• Remove deprecation warning from attribute_missing for attributes that are columns.

  Arun Agrawal

• Remove extra decrement of transaction deep level.

  Fixes #4566.

  Paul Nikitochkin

• Reset @column_defaults when assigning locking_column. We had a potential problem. For example:

  class Post < ActiveRecord::Base self.column_defaults # if we call this unintentionally before setting locking_column ... self.locking_column = 'my_locking_column' end

  Post.column_defaults["my_locking_column"] => nil # expected value is 0 !

  kennyj

• Remove extra select and update queries on save/touch/destroy ActiveRecord model with belongs to reflection with option touch: true.

  Fixes #11288.

  Paul Nikitochkin

• Remove deprecated nil-passing to the following SchemaCache methods: primary_keys, tables, columns and columns_hash.

  Yves Senn

• Remove deprecated block filter from ActiveRecord::Migrator#migrate.

  Yves Senn

• Remove deprecated String constructor from ActiveRecord::Migrator.

  Yves Senn

• Remove deprecated scope use without passing a callable object.

  Arun Agrawal

• Remove deprecated transaction_joinable= in favor of begin_transaction with :joinable option.

  Arun Agrawal

• Remove deprecated decrement_open_transactions.

  Arun Agrawal

• Remove deprecated increment_open_transactions.

  Arun Agrawal

• Remove deprecated PostgreSQLAdapter#outside_transaction? method. You can use #transaction_open? instead.

  Yves Senn

• Remove deprecated ActiveRecord::Fixtures.find_table_name in favor of ActiveRecord::Fixtures.default_fixture_model_name.

  Vipul A M

• Removed deprecated columns_for_remove from SchemaStatements.

  Neeraj Singh

• Remove deprecated SchemaStatements#distinct.

  Francesco Rodriguez

• Move deprecated ActiveRecord::TestCase into the rails test suite. The class is no longer public and is only used for internal Rails tests.

  Yves Senn

• Removed support for deprecated option :restrict for :dependent in associations.

  Neeraj Singh

• Removed support for deprecated delete_sql in associations.

  Neeraj Singh

• Removed support for deprecated insert_sql in associations.

  Neeraj Singh

• Removed support for deprecated finder_sql in associations.

  Neeraj Singh

• Support array as root element in JSON fields.

  Alexey Noskov & Francesco Rodriguez

• Removed support for deprecated counter_sql in associations.

  Neeraj Singh

• Do not invoke callbacks when delete_all is called on collection.

  Method delete_all should not be invoking callbacks and this feature was deprecated in Rails 4.0. This is being removed. delete_all will continue to honor the :dependent option. However if :dependent value is :destroy then the :delete_all deletion strategy for that collection will be applied.

  User can also force a deletion strategy by passing parameter to delete_all. For example you can do @post.comments.delete_all(:nullify).

  Neeraj Singh

• Calling default_scope without a proc will now raise ArgumentError.

  Neeraj Singh

• Removed deprecated method type_cast_code from Column.

  Neeraj Singh

• Removed deprecated options delete_sql and insert_sql from HABTM association.

  Removed deprecated options finder_sql and counter_sql from collection association.

  Neeraj Singh

• Remove deprecated ActiveRecord::Base#connection method. Make sure to access it via the class.

  Yves Senn

• Remove deprecation warning for auto_explain_threshold_in_seconds.

  Yves Senn

• Remove deprecated :distinct option from Relation#count.

  Yves Senn

• Removed deprecated methods partial_updates, partial_updates? and partial_updates=.

  Neeraj Singh

• Removed deprecated method scoped.

  Neeraj Singh

• Removed deprecated method default_scopes?.

  Neeraj Singh

• Remove implicit join references that were deprecated in 4.0.

  Example:

  # before with implicit joins
  Comment.where('posts.author_id' => 7)
  
  # after
  Comment.references(:posts).where('posts.author_id' => 7)
  

  Yves Senn

• Apply default scope when joining associations. For example:

  class Post < ActiveRecord::Base
    default_scope -> { where published: true }
  end
  
  class Comment
    belongs_to :post
  end
  

  When calling Comment.joins(:post), we expect to receive only comments on published posts, since that is the default scope for posts.

  Before this change, the default scope from Post was not applied, so we'd get comments on unpublished posts.

  Jon Leighton

• Remove activerecord-deprecated_finders as a dependency.

  Łukasz Strzałkowski

• Remove Oracle / Sqlserver / Firebird database tasks that were deprecated in 4.0.

  kennyj

• find_each now returns an Enumerator when called without a block, so that it can be chained with other Enumerable methods.

  Ben Woosley

• ActiveRecord::Result.each now returns an Enumerator when called without a block, so that it can be chained with other Enumerable methods.

  Ben Woosley

• Flatten merged join_values before building the joins.

  While joining_values special treatment is given to string values. By flattening the array it ensures that string values are detected as strings and not arrays.

  Fixes #10669.

  Neeraj Singh and iwiznia

• Do not load all child records for inverse case.

  currently post.comments.find(Comment.first.id) would load all comments for the given post to set the inverse association.

  This has a huge performance penalty. Because if post has 100k records and all these 100k records would be loaded in memory even though the comment id was supplied.

  Fix is to use in-memory records only if loaded? is true. Otherwise load the records using full sql.

  Fixes #10509.

  Neeraj Singh

• inspect on Active Record model classes does not initiate a new connection. This means that calling inspect, when the database is missing, will no longer raise an exception. Fixes #10936.

  Example:

  Author.inspect # => "Author(no database connection)"
  

  Yves Senn

• Handle single quotes in PostgreSQL default column values. Fixes #10881.

  Dylan Markow

• Log the sql that is actually sent to the database.

  If I have a query that produces sql WHERE "users"."name" = 'a b' then in the log all the whitespace is being squeezed. So the sql that is printed in the log is WHERE "users"."name" = 'a b'.

  Do not squeeze whitespace out of sql queries. Fixes #10982.

  Neeraj Singh

• Fixture setup no longer depends on ActiveRecord::Base.configurations. This is relevant when ENV["DATABASE_URL"] is used in place of a database.yml.

  Yves Senn

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

  Yves Senn

• Ambiguous reflections are on :through relationships are no longer supported. For example, you need to change this:

  class Author < ActiveRecord::Base
    has_many :posts
    has_many :taggings, through: :posts
  end
  
  class Post < ActiveRecord::Base
    has_one :tagging
    has_many :taggings
  end
  
  class Tagging < ActiveRecord::Base
  end
  

  To this:

  class Author < ActiveRecord::Base
    has_many :posts
    has_many :taggings, through: :posts, source: :tagging
  end
  
  class Post < ActiveRecord::Base
    has_one :tagging
    has_many :taggings
  end
  
  class Tagging < ActiveRecord::Base
  end
  

  Aaron Patterson

• Remove column restrictions for count, let the database raise if the SQL is invalid. The previous behavior was untested and surprising for the user. Fixes #5554.

  Example:

  User.select("name, username").count
  # Before => SELECT count(*) FROM users
  # After => ActiveRecord::StatementInvalid
  
  # you can still use `count(:all)` to perform a query unrelated to the
  # selected columns
  User.select("name, username").count(:all) # => SELECT count(*) FROM users
  

  Yves Senn

• Rails now automatically detects inverse associations. If you do not set the :inverse_of option on the association, then Active Record will guess the inverse association based on heuristics.

  Note that automatic inverse detection only works on has_many, has_one, and belongs_to associations. Extra options on the associations will also prevent the association's inverse from being found automatically.

  The automatic guessing of the inverse association uses a heuristic based on the name of the class, so it may not work for all associations, especially the ones with non-standard names.

  You can turn off the automatic detection of inverse associations by setting the :inverse_of option to false like so:

  class Taggable < ActiveRecord::Base
    belongs_to :tag, inverse_of: false
  end
  

  John Wang

• Fix add_column with array option when using PostgreSQL. Fixes #10432

  Adam Anderson

• Usage of implicit_readonly is being removed. Please use readonlymethod explicitly to mark records asreadonly. Fixes #10615.

  Example:

  user = User.joins(:todos).select("users.*, todos.title as todos_title").readonly(true).first
  user.todos_title = 'clean pet'
  user.save! # will raise error
  

  Yves Senn

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

  Yves Senn

• Fix bug where tiny types are incorrectly coerced as boolean when the length is more than 1.

  Fixes #10620.

  Aaron Patterson

• Also support extensions in PostgreSQL 9.1. This feature has been supported since 9.1.

  kennyj

• Deprecate ConnectionAdapters::SchemaStatements#distinct, as it is no longer used by internals.

  Ben Woosley

• Fix pending migrations error when loading schema and ActiveRecord::Base.table_name_prefix is not blank.

  Call assume_migrated_upto_version on connection to prevent it from first being picked up in method_missing.

  In the base class, Migration, method_missing expects the argument to be a table name, and calls proper_table_name on the arguments before sending to connection. If table_name_prefix or table_name_suffix is used, the schema version changes to prefix_version_suffix, breaking rake test:prepare.

  Fixes #10411.

  Kyle Stevens

• Method read_attribute_before_type_cast should accept input as symbol.

  Neeraj Singh

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

  Ben Tucker

• Fixed a bug in ActiveRecord#sanitize_sql_hash_for_conditions in which self.class is an argument to PredicateBuilder#build_from_hash causing PredicateBuilder to call non-existent method Class#reflect_on_association.

  Zach Ohlgren

• While removing index if column option is missing then raise IrreversibleMigration exception.

  Following code should raise IrreversibleMigration. But the code was failing since options is an array and not a hash.

  def change
    change_table :users do |t|
      t.remove_index [:name, :email]
    end
  end
  

  Fix was to check if the options is a Hash before operating on it.

  Fixes #10419.

  Neeraj Singh

• Do not overwrite manually built records during one-to-one nested attribute assignment

  For one-to-one nested associations, if you build the new (in-memory) child object yourself before assignment, then the NestedAttributes module will not overwrite it, e.g.:

  class Member < ActiveRecord::Base
    has_one :avatar
    accepts_nested_attributes_for :avatar
  
    def avatar
      super || build_avatar(width: 200)
    end
  end
  
  member = Member.new
  member.avatar_attributes = {icon: 'sad'}
  member.avatar.width # => 200
  

  Olek Janiszewski

• 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.

  Johnny Holton

• Handle aliased attributes in ActiveRecord::Relation.

  When using symbol keys, ActiveRecord will now translate aliased attribute names to the actual column name used in the database:

  With the model

  class Topic
    alias_attribute :heading, :title
  end
  

  The call

  Topic.where(heading: 'The First Topic')
  

  should yield the same result as

  Topic.where(title: 'The First Topic')
  

  This also applies to ActiveRecord::Relation::Calculations calls such as Model.sum(:aliased) and Model.pluck(:aliased).

  This will not work with SQL fragment strings like Model.sum('DISTINCT aliased').

  Godfrey Chan

• Mute psql output when running rake db:schema:load.

  Godfrey Chan

• Trigger a save on has_one association=(associate) when the associate contents have changed.

  Fix #8856.

  Chris Thompson

• Abort a rake task when missing db/structure.sql like db:schema:load task.

  kennyj

• rake:db:test:prepare falls back to original environment after execution.

  Slava Markevich

Please check 4-0-stable for previous changes.