rails--rails/activerecord/CHANGELOG.md

• Don't autosave unchanged has_one through records.

  Alan Kennedy, Steve Parrington

• Do not dump foreign keys for ignored tables. Yves Senn

• PostgreSQL adapter correctly dumps foreign keys targeting tables outside the schema search path.

  Fixes #16907.

  Matthew Draper, Yves Senn

• When a thread is killed, rollback the active transaction, instead of committing it during the stack unwind. Previously, we could commit half- completed work. This fix only works for Ruby 2.0+; on 1.9, we can't distinguish a thread kill from an ordinary non-local (block) return, so must default to committing.

  Chris Hanks

• A NullRelation should represent nothing. This fixes a bug where Comment.where(post_id: Post.none) returned a non-empty result.

  Fixes #15176.

  Matthew Draper, Yves Senn

• Include default column limits in schema.rb. Allows defaults to be changed in the future without affecting old migrations that assumed old defaults.

  Jeremy Kemper

• MySQL: schema.rb now includes TEXT and BLOB column limits.

  Jeremy Kemper

• MySQL: correct LONGTEXT and LONGBLOB limits from 2GB to their true 4GB.

  Jeremy Kemper

• SQLite3Adapter now checks for views in table_exists?. Fixes #14041.

  Girish Sonawane

• Introduce connection.supports_views? to check whether the current adapter has support for SQL views. Connection adapters should define this method.

  Yves Senn

• Allow included modules to override association methods.

  Fixes #16684.

  Yves Senn

• Schema loading rake tasks (like db:schema:load and db:setup) maintain the database connection to the current environment.

  Fixes #16757.

  Joshua Cody, Yves Senn

• MySQL: set the connection collation along with the charset.

  Sets the connection collation to the database collation configured in database.yml. Otherwise, SET NAMES utf8mb4 will use the default collation for that charset (utf8mb4_general_ci) when you may have chosen a different collation, like utf8mb4_unicode_ci.

  This only applies to literal string comparisons, not column values, so it is unlikely to affect you.

  Jeremy Kemper

• default_sequence_name from the PostgreSQL adapter returns a String.

  Yves Senn

• Fixed a regression where whitespaces were stripped from DISTINCT queries in PostgreSQL.

  Agis Anastasopoulos

  Fixes #16623.

• Fix has_many :through relation merging failing when dynamic conditions are passed as a lambda with an arity of one.

  Fixes #16128.

  Agis Anastasopoulos

• Fixed Relation#exists? to work with polymorphic associations.

  Fixes #15821.

  Kassio Borges

• Currently, Active Record rescues any errors raised within after_rollback/after_create callbacks and prints them to the logs. Future versions of Rails will not rescue these errors anymore and just bubble them up like the other callbacks.

  This commit adds an opt-in flag to enable not rescuing the errors.

  Example:

  # Do not swallow errors in after_commit/after_rollback callbacks.
  config.active_record.raise_in_transactional_callbacks = true
  

  Fixes #13460.

  arthurnn

• Fixed an issue where custom accessor methods (such as those generated by enum) with the same name as a global method are incorrectly overridden when subclassing.

  Fixes #16288.

  Godfrey Chan

• *_was and changes now work correctly for in-place attribute changes as well.

  Sean Griffin

• Fix regression on after_commit that did not fire with nested transactions.

  Fixes #16425.

  arthurnn

• Do not try to write timestamps when a table has no timestamps columns.

  Fixes #8813.

  Sergey Potapov

• index_exists? with :name option does verify specified columns.

  Example:

  add_index :articles, :title, name: "idx_title"
  
  # Before:
  index_exists? :articles, :title, name: "idx_title" # => `true`
  index_exists? :articles, :body, name: "idx_title" # => `true`
  
  # After:
  index_exists? :articles, :title, name: "idx_title" # => `true`
  index_exists? :articles, :body, name: "idx_title" # => `false`
  

  Yves Senn, Matthew Draper

• When calling update_columns on a record that is not persisted, the error message now reflects whether that object is a new record or has been destroyed.

  Lachlan Sylvester

• Define id_was to get the previous value of the primary key.

  Currently when we call id_was and we have a custom primary key name, Active Record will return the current value of the primary key. This makes it impossible to correctly do an update operation if you change the id.

  Fixes #16413.

  Rafael Mendonça França

• Deprecate DatabaseTasks.load_schema to act on the current connection. Use .load_schema_current instead. In the future load_schema will require the configuration to act on as an argument.

  Yves Senn

• Fixed automatic maintaining test schema to properly handle sql structure schema format.

  Fixes #15394.

  Wojciech Wnętrzak

• Fix type casting to Decimal from Float with large precision.

  Tomohiro Hashidate

• Deprecate Reflection#source_macro

  Reflection#source_macro is no longer needed in Active Record source so it has been deprecated. Code that used source_macro was removed in #16353.

  Eileen M. Uchtitelle, Aaron Patterson

• No verbose backtrace by db:drop when database does not exist.

  Fixes #16295.

  Kenn Ejima

• Add support for Postgresql JSONB.

  Example:

  create_table :posts do |t|
    t.jsonb :meta_data
  end
  

  Philippe Creux, Chris Teague

• db:purge with MySQL respects Rails.env.

  Yves Senn

• change_column_default :table, :column, nil with PostgreSQL will issue a DROP DEFAULT instead of a DEFAULT NULL query.

  Fixes #16261.

  Matthew Draper, Yves Senn

• Allow to specify a type for the foreign key column in references and add_reference.

  Example:

  change_table :vehicle do |t|
    t.references :station, type: :uuid
  end
  

  Andrey Novikov, Łukasz Sarnacki

• create_join_table removes a common prefix when generating the join table. This matches the existing behavior of HABTM associations.

  Fixes #13683.

  Stefan Kanev

• Do not swallow errors on compute_type when having a bad alias_method on a class.

  arthurnn

• PostgreSQL invalid uuid are convert to nil.

  Abdelkader Boudih

• Restore 4.0 behavior for using serialize attributes with JSON as coder.

  With 4.1.x, serialize started returning a string when JSON was passed as the second attribute. It will now return a hash as per previous versions.

  Example:

  class Post < ActiveRecord::Base
    serialize :comment, JSON
  end
  
  class Comment
    include ActiveModel::Model
    attr_accessor :category, :text
  end
  
  post = Post.create!
  post.comment = Comment.new(category: "Animals", text: "This is a comment about squirrels.")
  post.save!
  
  # 4.0
  post.comment # => {"category"=>"Animals", "text"=>"This is a comment about squirrels."}
  
  # 4.1 before
  post.comment # => "#<Comment:0x007f80ab48ff98>"
  
  # 4.1 after
  post.comment # => {"category"=>"Animals", "text"=>"This is a comment about squirrels."}
  

  When using JSON as the coder in serialize, Active Record will use the new ActiveRecord::Coders::JSON coder which delegates its dump/load to ActiveSupport::JSON.encode/decode. This ensures special objects are dumped correctly using the #as_json hook.

  To keep the previous behaviour, supply a custom coder instead (example).

  Fixes #15594.

  Jenn Cooper

• Do not use RENAME INDEX syntax for MariaDB 10.0.

  Fixes #15931.

  Jeff Browning

• Calling #empty? on a has_many association would use the value from the counter cache if one exists.

  David Verhasselt

• Fix the schema dump generated for tables without constraints and with primary key with default value of custom PostgreSQL function result.

  Fixes #16111.

  Andrey Novikov

• Fix the SQL generated when a delete_all is run on an association to not produce an IN statements.

  Before:

  UPDATE "categorizations" SET "category_id" = NULL WHERE "categorizations"."category_id" = 1 AND "categorizations"."id" IN (1, 2)

  After:

  UPDATE "categorizations" SET "category_id" = NULL WHERE "categorizations"."category_id" = 1

  Eileen M. Uchitelle, Aaron Patterson

• Avoid type casting boolean and ActiveSupport::Duration values to numeric values for string columns. Otherwise, in some database, the string column values will be coerced to a numeric allowing false or 0.seconds match any string starting with a non-digit.

  Example:

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

  Dylan Thacker-Smith

• Add a :required option to singular associations, providing a nicer API for presence validations on associations.

  Sean Griffin

• Fixed error in reset_counters when associations have select scope. (Call to count generates invalid SQL.)

  Cade Truitt

• After a successful reload, new_record? is always false.

  Fixes #12101.

  Matthew Draper

• PostgreSQL renaming table doesn't attempt to rename non existent sequences.

  Abdelkader Boudih

• Move 'dependent: :destroy' handling for belongs_to from before_destroy to after_destroy callback chain

  Fixes #12380.

  Ivan Antropov

• Detect in-place modifications on String attributes.

  Before this change, an attribute modified in-place had to be marked as changed in order for it to be persisted in the database. Now it is no longer required.

  Before:

  user = User.first
  user.name << ' Griffin'
  user.name_will_change!
  user.save
  user.reload.name # => "Sean Griffin"
  

  After:

  user = User.first
  user.name << ' Griffin'
  user.save
  user.reload.name # => "Sean Griffin"
  

  Sean Griffin

• Add ActiveRecord::Base#validate! that raises RecordInvalid if the record is invalid.

  Bogdan Gusiev, Marc Schütz

• Support for adding and removing foreign keys. Foreign keys are now a part of schema.rb. This is supported by Mysql2Adapter, MysqlAdapter and PostgreSQLAdapter.

  Many thanks to Matthew Higgins for laying the foundation with his work on foreigner.

  Example:

  # within your migrations:
  add_foreign_key :articles, :authors
  remove_foreign_key :articles, :authors
  

  Yves Senn

• Fix subtle bugs regarding attribute assignment on models with no primary key. 'id' will no longer be part of the attributes hash.

  Sean Griffin

• Deprecate automatic counter caches on has_many :through. The behavior was broken and inconsistent.

  Sean Griffin

• preload preserves readonly flag for associations.

  See #15853.

  Yves Senn

• Assume numeric types have changed if they were assigned to a value that would fail numericality validation, regardless of the old value. Previously this would only occur if the old value was 0.

  Example:

  model = Model.create!(number: 5)
  model.number = '5wibble'
  model.number_changed? # => true
  

  Fixes #14731.

  Sean Griffin

• reload no longer merges with the existing attributes. The attribute hash is fully replaced. The record is put into the same state as it would be with Model.find(model.id).

  Sean Griffin

• The object returned from select_all must respond to column_types. If this is not the case a NoMethodError is raised.

  Sean Griffin

• Detect in-place modifications of PG array types

  Sean Griffin

• Add bin/rake db:purge task to empty the current database.

  Yves Senn

• Deprecate serialized_attributes without replacement.

  Sean Griffin

• Correctly extract IPv6 addresses from DATABASE_URI: the square brackets are part of the URI structure, not the actual host.

  Fixes #15705.

  Andy Bakun, Aaron Stone

• Ensure both parent IDs are set on join records when both sides of a through association are new.

  Sean Griffin

• ActiveRecord::Dirty now detects in-place changes to mutable values. Serialized attributes on ActiveRecord models will no longer save when unchanged.

  Fixes #8328.

  Sean Griffin

• Pluck now works when selecting columns from different tables with the same name.

  Fixes #15649.

  Sean Griffin

• Remove cache_attributes and friends. All attributes are cached.

  Sean Griffin

• Remove deprecated method ActiveRecord::Base.quoted_locking_column.

  Akshay Vishnoi

• ActiveRecord::FinderMethods.find with block can handle proc parameter as Enumerable#find does.

  Fixes #15382.

  James Yang

• Make timezone aware attributes work with PostgreSQL array columns.

  Fixes #13402.

  Kuldeep Aggarwal, Sean Griffin

• ActiveRecord::SchemaMigration has no primary key regardless of the primary_key_prefix_type configuration.

  Fixes #15051.

  JoseLuis Torres, Yves Senn

• rake db:migrate:status works with legacy migration numbers like 00018_xyz.rb.

  Fixes #15538.

  Yves Senn

• Baseclass becomes! subclass.

  Before this change, a record which changed its STI type, could not be updated.

  Fixes #14785.

  Matthew Draper, Earl St Sauver, Edo Balvers

• Remove deprecated ActiveRecord::Migrator.proper_table_name. Use the proper_table_name instance method on ActiveRecord::Migration instead.

  Akshay Vishnoi

• Fix regression on eager loading association based on SQL query rather than existing column.

  Fixes #15480.

  Lauro Caetano, Carlos Antonio da Silva

• Deprecate returning nil from column_for_attribute when no column exists. It will return a null object in Rails 5.0

  Sean Griffin

• Implemented ActiveRecord::Base#pretty_print to work with PP.

  Ethan

• Preserve type when dumping PostgreSQL point, bit, bit varying and money columns.

  Yves Senn

• New records remain new after YAML serialization.

  Sean Griffin

• PostgreSQL support default values for enum types. Fixes #7814.

  Yves Senn

• PostgreSQL default_sequence_name respects schema. Fixes #7516.

  Yves Senn

• Fixed columns_for_distinct of postgresql adapter to work correctly with orders without sort direction modifiers.

  Nikolay Kondratyev

• PostgreSQL reset_pk_sequence! respects schemas. Fixes #14719.

  Yves Senn

• Keep PostgreSQL hstore and json attributes as Hash in @attributes. Fixes duplication in combination with store_accessor.

  Fixes #15369.

  Yves Senn

• rake railties:install:migrations respects the order of railties.

  Arun Agrawal

• Fix redefine a has_and_belongs_to_many inside inherited class Fixing regression case, where redefining the same has_and_belongs_to_many definition into a subclass would raise.

  Fixes #14983.

  arthurnn

• Fix has_and_belongs_to_many public reflection. When defining a has_and_belongs_to_many, internally we convert that to two has_many. But as reflections is a public API, people expect to see the right macro.

  Fixes #14682.

  arthurnn

• Fixed serialization for records with an attribute named format.

  Fixes #15188.

  Godfrey Chan

• When a group is set, sum, size, average, minimum and maximum on a NullRelation should return a Hash.

  Kuldeep Aggarwal

• Fixed serialized fields returning serialized data after being updated with update_column.

  Simon Hørup Eskildsen

• Fixed polymorphic eager loading when using a String as foreign key.

  Fixes #14734.

  Lauro Caetano

• Change belongs_to touch to be consistent with timestamp updates

  If a model is set up with a belongs_to: touch relationship the parent record will only be touched if the record was modified. This makes it consistent with timestamp updating on the record itself.

  Brock Trappitt

• Fixed the inferred table name of a has_and_belongs_to_many auxiliar table inside a schema.

  Fixes #14824.

  Eric Chahin

• Remove unused :timestamp type. Transparently alias it to :datetime in all cases. Fixes inconsistencies when column types are sent outside of ActiveRecord, such as for XML Serialization.

  Sean Griffin

• Fix bug that added table_name_prefix and table_name_suffix to extension names in PostgreSQL when migrating.

  Joao Carlos

• The :index option in migrations, which previously was only available for references, now works with any column types.

  Marc Schütz

• Add support for counter name to be passed as parameter on CounterCache::ClassMethods#reset_counters.

  jnormore

• Restrict deletion of record when using delete_all with uniq, group, having or offset.

  In these cases the generated query ignored them and that caused unintended records to be deleted.

  Fixes #11985.

  Leandro Facchinetti

• Floats with limit >= 25 that get turned into doubles in MySQL no longer have their limit dropped from the schema.

  Fixes #14135.

  Aaron Nelson

• Fix how to calculate associated class name when using namespaced has_and_belongs_to_many association.

  Fixes #14709.

  Kassio Borges

• ActiveRecord::Relation::Merger#filter_binds now compares equivalent symbols and strings in column names as equal.

  This fixes a rare case in which more bind values are passed than there are placeholders for them in the generated SQL statement, which can make PostgreSQL throw a StatementInvalid exception.

  Nat Budin

• Fix stored_attributes to correctly merge the details of stored attributes defined in parent classes.

  Fixes #14672.

  Brad Bennett, Jessica Yao, Lakshmi Parthasarathy

• change_column_default allows [] as argument to change_column_default.

  Fixes #11586.

  Yves Senn

• Handle name and "char" column types in the PostgreSQL adapter.

  name and "char" are special character types used internally by PostgreSQL and are used by internal system catalogs. These field types can sometimes show up in structure-sniffing queries that feature internal system structures or with certain PostgreSQL extensions.

  J Smith, Yves Senn

• Fix PostgreSQLAdapter::OID::Float#type_cast to convert Infinity and NaN PostgreSQL values into a native Ruby Float::INFINITY and Float::NAN

  Before:

  Point.create(value: 1.0/0)
  Point.last.value # => 0.0
  

  After:

  Point.create(value: 1.0/0)
  Point.last.value # => Infinity
  

  Innokenty Mikhailov

• Allow the PostgreSQL adapter to handle bigserial primary key types again.

  Fixes #10410.

  Patrick Robertson

• Deprecate joining, eager loading and preloading of instance dependent associations without replacement. These operations happen before instances are created. The current behavior is unexpected and can result in broken behavior.

  Fixes #15024.

  Yves Senn

• Fixed has_and_belongs_to_many's CollectionAssociation size calculation.

  has_and_belongs_to_many should fall back to using the normal CollectionAssociation's size calculation if the collection is not cached or loaded.

  Fixes #14913, #14914.

  Fred Wu

• Return a non zero status when running rake db:migrate:status and migration table does not exist.

  Paul B.

• Add support for module-level table_name_suffix in models.

  This makes table_name_suffix work the same way as table_name_prefix when using namespaced models.

  Jenner LaFave

• Revert the behaviour of ActiveRecord::Relation#join changed through 4.0 => 4.1 to 4.0.

  In 4.1.0 Relation#join is delegated to Arel#SelectManager. In 4.0 series it is delegated to Array#join.

  Bogdan Gusiev

• Log nil binary column values correctly.

  When an object with a binary column is updated with a nil value in that column, the SQL logger would throw an exception when trying to log that nil value. This only occurs when updating a record that already has a non-nil value in that column since an initial nil value isn't included in the SQL anyway (at least, when dirty checking is enabled.) The column's new value will now be logged as <NULL binary data> to parallel the existing <N bytes of binary data> for non-nil values.

  James Coleman

• Rails will now pass a custom validation context through to autosave associations in order to validate child associations with the same context.

  Fixes #13854.

  Eric Chahin, Aaron Nelson, Kevin Casey

• Stringify all variables keys of MySQL connection configuration.

  When sql_mode variable for MySQL adapters set in configuration as String was ignored and overwritten by strict mode option.

  Fixes #14895.

  Paul Nikitochkin

• Ensure SQLite3 statements are closed on errors.

  Fixes #13631.

  Timur Alperovich

• Give ActiveRecord::PredicateBuilder private methods the privacy they deserve.

  Hector Satre

• When using a custom join_table name on a habtm, rails was not saving it on Reflections. This causes a problem when rails loads fixtures, because it uses the reflections to set database with fixtures.

  Fixes #14845.

  Kassio Borges

• Reset the cache when modifying a Relation with cached Arel. Additionally display a warning message to make the user aware.

  Yves Senn

• PostgreSQL should internally use :datetime consistently for TimeStamp. Assures different spellings of timestamps are treated the same.

  Example:

  mytimestamp.simplified_type('timestamp without time zone')
  # => :datetime
  mytimestamp.simplified_type('timestamp(6) without time zone')
  # => also :datetime (previously would be :timestamp)
  

  See #14513.

  Jefferson Lai

• ActiveRecord::Base.no_touching no longer triggers callbacks or start empty transactions.

  Fixes #14841.

  Lucas Mazza

• Fix name collision with Array#select! with Relation#select!.

  Fixes #14752.

  Earl St Sauver

• Fixed unexpected behavior for has_many :through associations going through a scoped has_many.

  If a has_many association is adjusted using a scope, and another has_many :through uses this association, then the scope adjustment is unexpectedly neglected.

  Fixes #14537.

  Jan Habermann

• @destroyed should always be set to false when an object is duped.

  Kuldeep Aggarwal

• Fixed has_many association to make it support irregular inflections.

  Fixes #8928.

  arthurnn, Javier Goizueta

• Fixed a problem where count used with a grouping was not returning a Hash.

  Fixes #14721.

  Eric Chahin

• sanitize_sql_like helper method to escape a string for safe use in an SQL LIKE statement.

  Example:

  class Article
    def self.search(term)
      where("title LIKE ?", sanitize_sql_like(term))
    end
  end
  
  Article.search("20% _reduction_")
  # => Query looks like "... title LIKE '20\% \_reduction\_' ..."
  

  Rob Gilson, Yves Senn

• Do not quote uuid default value on change_column.

  Fixes #14604.

  Eric Chahin

• The comparison between Relation and CollectionProxy should be consistent.

  Example:

  author.posts == Post.where(author_id: author.id)
  # => true
  Post.where(author_id: author.id) == author.posts
  # => true
  

  Fixes #13506.

  Lauro Caetano

• Calling delete_all on an unloaded CollectionProxy no longer generates an SQL statement containing each id of the collection:

  Before:

  DELETE FROM `model` WHERE `model`.`parent_id` = 1
  AND `model`.`id` IN (1, 2, 3...)
  

  After:

  DELETE FROM `model` WHERE `model`.`parent_id` = 1
  

  Eileen M. Uchitelle, Aaron Patterson

• Fixed error for aggregate methods (empty?, any?, count) with select which created invalid SQL.

  Fixes #13648.

  Simon Woker

• PostgreSQL adapter only warns once for every missing OID per connection.

  Fixes #14275.

  Matthew Draper, Yves Senn

• PostgreSQL adapter automatically reloads it's type map when encountering unknown OIDs.

  Fixes #14678.

  Matthew Draper, Yves Senn

• Fix insertion of records via has_many :through association with scope.

  Fixes #3548.

  Ivan Antropov

• Auto-generate stable fixture UUIDs on PostgreSQL.

  Fixes #11524.

  Roderick van Domburg

• Fixed a problem where an enum would overwrite values of another enum with the same name in an unrelated class.

  Fixes #14607.

  Evan Whalen

• PostgreSQL and SQLite string columns no longer have a default limit of 255.

  Fixes #13435, #9153.

  Vladimir Sazhin, Toms Mikoss, Yves Senn

• Make possible to have an association called records.

  Fixes #11645.

  prathamesh-sonpatki

• to_sql on an association now matches the query that is actually executed, where it could previously have incorrectly accrued additional conditions (e.g. as a result of a previous query). CollectionProxy now always defers to the association scope's arel method so the (incorrect) inherited one should be entirely concealed.

  Fixes #14003.

  Jefferson Lai

• Block a few default Class methods as scope name.

  For instance, this will raise:

  scope :public, -> { where(status: 1) }
  

  arthurnn

• Fixed error when using with_options with lambda.

  Fixes #9805.

  Lauro Caetano

• Switch sqlite3:/// URLs (which were temporarily deprecated in 4.1) from relative to absolute.

  If you still want the previous interpretation, you should replace sqlite3:///my/path with sqlite3:my/path.

  Matthew Draper

• Treat blank UUID values as nil.

  Example:

  Sample.new(uuid_field: '') #=> <Sample id: nil, uuid_field: nil>
  

  Dmitry Lavrov

• Enable support for materialized views on PostgreSQL >= 9.3.

  Dave Lee

• The PostgreSQL adapter supports custom domains. Fixes #14305.

  Yves Senn

• PostgreSQL Column#type is now determined through the corresponding OID. The column types stay the same except for enum columns. They no longer have nil as type but enum.

  See #7814.

  Yves Senn

• Fixed error when specifying a non-empty default value on a PostgreSQL array column.

  Fixes #10613.

  Luke Steensen

• Fixed error where .persisted? throws SystemStackError for an unsaved model with a custom primary key that didn't save due to validation error.

  Fixes #14393.

  Chris Finne

• Introduce validate as an alias for valid?.

  This is more intuitive when you want to run validations but don't care about the return value.

  Henrik Nyh

• Create indexes inline in CREATE TABLE for MySQL.

  This is important, because adding an index on a temporary table after it has been created would commit the transaction.

  It also allows creating and dropping indexed tables with fewer queries and fewer permissions required.

  Example:

  create_table :temp, temporary: true, as: "SELECT id, name, zip FROM a_really_complicated_query" do |t|
    t.index :zip
  end
  # => CREATE TEMPORARY TABLE temp (INDEX (zip)) AS SELECT id, name, zip FROM a_really_complicated_query
  

  Cody Cutrer, Steve Rice, Rafael Mendonça Franca

• Use singular table name in generated migrations when ActiveRecord::Base.pluralize_table_names is false.

  Fixes #13426.

  Kuldeep Aggarwal

• touch accepts many attributes to be touched at once.

  Example:

  # touches :signed_at, :sealed_at, and :updated_at/on attributes.
  Photo.last.touch(:signed_at, :sealed_at)
  

  James Pinto

• rake db:structure:dump only dumps schema information if the schema migration table exists.

  Fixes #14217.

  Yves Senn

• Reap connections that were checked out by now-dead threads, instead of waiting until they disconnect by themselves. Before this change, a suitably constructed series of short-lived threads could starve the connection pool, without ever having more than a couple alive at the same time.

  Matthew Draper

• pk_and_sequence_for now ensures that only the pg_depend entries pointing to pg_class, and thus only sequence objects, are considered.

  Josh Williams

• where.not adds references for includes like normal where calls do.

  Fixes #14406.

  Yves Senn

• Extend fixture $LABEL replacement to allow string interpolation.

  Example:

  martin:
    email: $LABEL@email.com
  
  users(:martin).email # => martin@email.com
  

  Eric Steele

• Add support for Relation be passed as parameter on QueryCache#select_all.

  Fixes #14361.

  arthurnn

• Passing an Active Record object to find or exists? is now deprecated. Call .id on the object first.

  Aaron Patterson

• Only use BINARY for MySQL case sensitive uniqueness check when column has a case insensitive collation.

  Ryuta Kamizono

• Support for MySQL 5.6 fractional seconds.

  arthurnn, Tatsuhiko Miyagawa

• Support for Postgres citext data type enabling case-insensitive where values without needing to wrap in UPPER/LOWER sql functions.

  Troy Kruthoff, Lachlan Sylvester

• Only save has_one associations if record has changes. Previously after save related callbacks, such as #after_commit, were triggered when the has_one object did not get saved to the db.

  Alan Kennedy

• Allow strings to specify the #order value.

  Example:

  Model.order(id: 'asc').to_sql == Model.order(id: :asc).to_sql
  

  Marcelo Casiraghi, Robin Dupret

• Dynamically register PostgreSQL enum OIDs. This prevents "unknown OID" warnings on enum columns.

  Dieter Komendera

• includes is able to detect the right preloading strategy when string joins are involved.

  Fixes #14109.

  Aaron Patterson, Yves Senn

• Fixed error with validation with enum fields for records where the value for any enum attribute is always evaluated as 0 during uniqueness validation.

  Fixes #14172.

  Vilius Luneckas Ahmed AbouElhamayed

• before_add callbacks are fired before the record is saved on has_and_belongs_to_many associations and on has_many :through associations. Before this change, before_add callbacks would be fired before the record was saved on has_and_belongs_to_many associations, but not on has_many :through associations.

  Fixes #14144.

• Fixed STI classes not defining an attribute method if there is a conflicting private method defined on its ancestors.

  Fixes #11569.

  Godfrey Chan

• Coerce strings when reading attributes. Fixes #10485.

  Example:

  book = Book.new(title: 12345)
  book.save!
  book.title # => "12345"
  

  Yves Senn

• Deprecate half-baked support for PostgreSQL range values with excluding beginnings. We currently map PostgreSQL ranges to Ruby ranges. This conversion is not fully possible because the Ruby range does not support excluded beginnings.

  The current solution of incrementing the beginning is not correct and is now deprecated. For subtypes where we don't know how to increment (e.g. #succ is not defined) it will raise an ArgumentException for ranges with excluding beginnings.

  Yves Senn

• Support for user created range types in PostgreSQL.

  Yves Senn

Please check 4-1-stable for previous changes.