rails--rails/activerecord/CHANGELOG.md

• 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]
  Account.last.inspect # => #<Account id: 123, name: "DHH", credit_card_number: [FILTERED] ...>
  SecureAccount.filter_attributes += [:name]
  SecureAccount.last.inspect # => #<SecureAccount id: 42, name: [FILTERED], credit_card_number: [FILTERED] ...>
  

  Zhang Kang

• 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.