rails/activerecord/CHANGELOG.md

• MySQL: ROW_FORMAT=DYNAMIC create table option by default.

  Since MySQL 5.7.9, the innodb_default_row_format option defines the default row format for InnoDB tables. The default setting is DYNAMIC. The row format is required for indexing on varchar(255) with utf8mb4 columns.

  Ryuta Kamizono

• Fix join table column quoting with SQLite.

  Gannon McGibbon

• Allow disabling scopes generated by ActiveRecord.enum.

  Alfred Dominic

• Ensure that delete_all on collection proxy returns affected count.

  Ryuta Kamizono

• Reset scope after delete on collection association to clear stale offsets of removed records.

  Gannon McGibbon

• Add the ability to prevent writes to a database for the duration of a block.

  Allows the application to prevent writes to a database. This can be useful when you're building out multiple databases and want to make sure you're not sending writes when you want a read.

  If while_preventing_writes is called and the query is considered a write query the database will raise an exception regardless of whether the database user is able to write.

  This is not meant to be a catch-all for write queries but rather a way to enforce read-only queries without opening a second connection. One purpose of this is to catch accidental writes, not all writes.

  Eileen M. Uchitelle

• Allow aliased attributes to be used in #update_columns and #update.

  Gannon McGibbon

• Allow spaces in postgres table names.

  Fixes issue where "user post" is misinterpreted as ""user"."post"" when quoting table names with the postgres adapter.

  Gannon McGibbon

• Cached columns_hash fields should be excluded from ResultSet#column_types

  PR #34528 addresses the inconsistent behaviour when attribute is defined for an ignored column. The following test was passing for SQLite and MySQL, but failed for PostgreSQL:

  class DeveloperName < ActiveRecord::Type::String
    def deserialize(value)
      "Developer: #{value}"
    end
  end
  
  class AttributedDeveloper < ActiveRecord::Base
    self.table_name = "developers"
  
    attribute :name, DeveloperName.new
  
    self.ignored_columns += ["name"]
  end
  
  developer = AttributedDeveloper.create
  developer.update_column :name, "name"
  
  loaded_developer = AttributedDeveloper.where(id: developer.id).select("*").first
  puts loaded_developer.name # should be "Developer: name" but it's just "name"
  

  Dmitry Tsepelev

• Make the implicit order column configurable.

  When calling ordered finder methods such as +first+ or +last+ without an explicit order clause, ActiveRecord sorts records by primary key. This can result in unpredictable and surprising behaviour when the primary key is not an auto-incrementing integer, for example when it's a UUID. This change makes it possible to override the column used for implicit ordering such that +first+ and +last+ will return more predictable results.

  Example:

  class Project < ActiveRecord::Base
    self.implicit_order_column = "created_at"
  end
  

  Tekin Suleyman

• Bump minimum PostgreSQL version to 9.3.

  Yasuo Honda

• Values of enum are frozen, raising an error when attempting to modify them.

  Emmanuel Byrd

• Move ActiveRecord::StatementInvalid SQL to error property and include binds as separate error property.

  ActiveRecord::ConnectionAdapters::AbstractAdapter#translate_exception_class now requires binds to be passed as the last argument.

  ActiveRecord::ConnectionAdapters::AbstractAdapter#translate_exception now requires message, sql, and binds to be passed as keyword arguments.

  Subclasses of ActiveRecord::StatementInvalid must now provide sql: and binds: arguments to super.

  Example:

  class MySubclassedError < ActiveRecord::StatementInvalid
    def initialize(message, sql:, binds:)
      super(message, sql: sql, binds: binds)
    end
  end
  

  Gannon McGibbon

• Add an :if_not_exists option to create_table.

  Example:

  create_table :posts, if_not_exists: true do |t|
    t.string :title
  end
  

  That would execute:

  CREATE TABLE IF NOT EXISTS posts (
    ...
  )
  

  If the table already exists, if_not_exists: false (the default) raises an exception whereas if_not_exists: true does nothing.

  fatkodima, Stefan Kanev

• Defining an Enum as a Hash with blank key, or as an Array with a blank value, now raises an ArgumentError.

  Christophe Maximin

• Adds support for multiple databases to rails db:schema:cache:dump and rails db:schema:cache:clear.

  Gannon McGibbon

• update_columns now correctly raises ActiveModel::MissingAttributeError if the attribute does not exist.

  Sean Griffin

• Add support for hash and url configs in database hash of ActiveRecord::Base.connected_to.

  User.connected_to(database: { writing: "postgres://foo" }) do
    User.create!(name: "Gannon")
  end
  
  config = { "adapter" => "sqlite3", "database" => "db/readonly.sqlite3" }
  User.connected_to(database: { reading: config }) do
    User.count
  end
  

  Gannon McGibbon

• Support default expression for MySQL.

  MySQL 8.0.13 and higher supports default value to be a function or expression.

  https://dev.mysql.com/doc/refman/8.0/en/create-table.html

  Ryuta Kamizono

• Support expression indexes for MySQL.

  MySQL 8.0.13 and higher supports functional key parts that index expression values rather than column or column prefix values.

  https://dev.mysql.com/doc/refman/8.0/en/create-index.html

  Ryuta Kamizono

• Fix collection cache key with limit and custom select to avoid ambiguous timestamp column error.

  Fixes #33056.

  Federico Martinez

• Add basic API for connection switching to support multiple databases.

  1. Adds a connects_to method for models to connect to multiple databases. Example:

  class AnimalsModel < ApplicationRecord
    self.abstract_class = true
  
    connects_to database: { writing: :animals_primary, reading: :animals_replica }
  end
  
  class Dog < AnimalsModel
    # connected to both the animals_primary db for writing and the animals_replica for reading
  end
  

  2. Adds a connected_to block method for switching connection roles or connecting to a database that the model didn't connect to. Connecting to the database in this block is useful when you have another defined connection, for example slow_replica that you don't want to connect to by default but need in the console, or a specific code block.

  ActiveRecord::Base.connected_to(role: :reading) do
    Dog.first # finds dog from replica connected to AnimalsBase
    Book.first # doesn't have a reading connection, will raise an error
  end
  

  ActiveRecord::Base.connected_to(database: :slow_replica) do
    SlowReplicaModel.first # if the db config has a slow_replica configuration this will be used to do the lookup, otherwise this will throw an exception
  end
  

  Eileen M. Uchitelle

• Enum raises on invalid definition values

  When defining a Hash enum it can be easy to use [] instead of {}. This commit checks that only valid definition values are provided, those can be a Hash, an array of Symbols or an array of Strings. Otherwise it raises an ArgumentError.

  Fixes #33961

  Alberto Almagro

• Reloading associations now clears the Query Cache like Persistence#reload does.

  class Post < ActiveRecord::Base
    has_one :category
    belongs_to :author
    has_many :comments
  end
  
  # Each of the following will now clear the query cache.
  post.reload_category
  post.reload_author
  post.comments.reload
  

  Christophe Maximin

• Added index option for change_table migration helpers. With this change you can create indexes while adding new columns into the existing tables.

  Example:

  change_table(:languages) do |t|
    t.string :country_code, index: true
  end
  

  Mehmet Emin İNAÇ

• Fix transaction reverting for migrations.

  Before: Commands inside a transaction in a reverted migration ran uninverted. Now: This change fixes that by reverting commands inside transaction block.

  fatkodima, David Verhasselt

• Raise an error instead of scanning the filesystem root when fixture_path is blank.

  Gannon McGibbon, Max Albrecht

• Allow ActiveRecord::Base.configurations= to be set with a symbolized hash.

  Gannon McGibbon

• Don't update counter cache unless the record is actually saved.

  Fixes #31493, #33113, #33117.

  Ryuta Kamizono

• Deprecate ActiveRecord::Result#to_hash in favor of ActiveRecord::Result#to_a.

  Gannon McGibbon, Kevin Cheng

• SQLite3 adapter supports expression indexes.

  create_table :users do |t|
    t.string :email
  end
  
  add_index :users, 'lower(email)', name: 'index_users_on_email', unique: true
  

  Gray Kemmey

• Allow subclasses to redefine autosave callbacks for associated records.

  Fixes #33305.

  Andrey Subbota

• Bump minimum MySQL version to 5.5.8.

  Yasuo Honda

• Use MySQL utf8mb4 character set by default.

  utf8mb4 character set with 4-Byte encoding supports supplementary characters including emoji. The previous default 3-Byte encoding character set utf8 is not enough to support them.

  Yasuo Honda

• Fix duplicated record creation when using nested attributes with create_with.

  Darwin Wu

• Configuration item config.filter_parameters could also filter out sensitive values of database columns when call #inspect. We also added ActiveRecord::Base::filter_attributes/= in order to specify sensitive attributes to specific model.

  Rails.application.config.filter_parameters += [:credit_card_number, /phone/]
  Account.last.inspect # => #<Account id: 123, name: "DHH", credit_card_number: [FILTERED], telephone_number: [FILTERED] ...>
  SecureAccount.filter_attributes += [:name]
  SecureAccount.last.inspect # => #<SecureAccount id: 42, name: [FILTERED], credit_card_number: [FILTERED] ...>
  

  Zhang Kang, Yoshiyuki Kinjo

• Deprecate column_name_length, table_name_length, columns_per_table, indexes_per_table, columns_per_multicolumn_index, sql_query_length, and joins_per_query methods in DatabaseLimits.

  Ryuta Kamizono

• ActiveRecord::Base.configurations now returns an object.

  ActiveRecord::Base.configurations used to return a hash, but this is an inflexible data model. In order to improve multiple-database handling in Rails, we've changed this to return an object. Some methods are provided to make the object behave hash-like in order to ease the transition process. Since most applications don't manipulate the hash we've decided to add backwards-compatible functionality that will throw a deprecation warning if used, however calling ActiveRecord::Base.configurations will use the new version internally and externally.

  For example, the following database.yml:

  development:
    adapter: sqlite3
    database: db/development.sqlite3
  

  Used to become a hash:

  { "development" => { "adapter" => "sqlite3", "database" => "db/development.sqlite3" } }
  

  Is now converted into the following object:

  #<ActiveRecord::DatabaseConfigurations:0x00007fd1acbdf800 @configurations=[
    #<ActiveRecord::DatabaseConfigurations::HashConfig:0x00007fd1acbded10 @env_name="development",
      @spec_name="primary", @config={"adapter"=>"sqlite3", "database"=>"db/development.sqlite3"}>
    ]
  

  Iterating over the database configurations has also changed. Instead of calling hash methods on the configurations hash directly, a new method configs_for has been provided that allows you to select the correct configuration. env_name, and spec_name arguments are optional. For example these return an array of database config objects for the requested environment and a single database config object will be returned for the requested environment and specification name respectively.

  ActiveRecord::Base.configurations.configs_for(env_name: "development")
  ActiveRecord::Base.configurations.configs_for(env_name: "development", spec_name: "primary")
  

  Eileen M. Uchitelle, Aaron Patterson

• Add database configuration to disable advisory locks.

  production:
    adapter: postgresql
    advisory_locks: false
  

  Guo Xiang

• SQLite3 adapter alter_table method restores foreign keys.

  Yasuo Honda

• Allow :to_table option to invert_remove_foreign_key.

  Example:

  remove_foreign_key :accounts, to_table: :owners

  Nikolay Epifanov, Rich Chen

• Add environment & load_config dependency to bin/rake db:seed to enable seed load in environments without Rails and custom DB configuration

  Tobias Bielohlawek

• Fix default value for mysql time types with specified precision.

  Nikolay Kondratyev

• Fix touch option to behave consistently with Persistence#touch method.

  Ryuta Kamizono

• Migrations raise when duplicate column definition.

  Fixes #33024.

  Federico Martinez

• Bump minimum SQLite version to 3.8

  Yasuo Honda

• Fix parent record should not get saved with duplicate children records.

  Fixes #32940.

  Santosh Wadghule

• Fix logic on disabling commit callbacks so they are not called unexpectedly when errors occur.

  Brian Durand

• Ensure Associations::CollectionAssociation#size and Associations::CollectionAssociation#empty? use loaded association ids if present.

  Graham Turner

• Add support to preload associations of polymorphic associations when not all the records have the requested associations.

  Dana Sherson

• Add touch_all method to ActiveRecord::Relation.

  Example:

  Person.where(name: "David").touch_all(time: Time.new(2020, 5, 16, 0, 0, 0))
  

  fatkodima, duggiefresh

• Add ActiveRecord::Base.base_class? predicate.

  Bogdan Gusiev

• Add custom prefix/suffix options to ActiveRecord::Store.store_accessor.

  Tan Huynh, Yukio Mizuta

• Rails 6 requires Ruby 2.4.1 or newer.

  Jeremy Daer

• Deprecate update_attributes/! in favor of update/!.

  Eddie Lebow

• Add ActiveRecord::Base.create_or_find_by/! to deal with the SELECT/INSERT race condition in ActiveRecord::Base.find_or_create_by/! by leaning on unique constraints in the database.

  DHH

• Add Relation#pick as short-hand for single-value plucks.

  DHH

Please check 5-2-stable for previous changes.