rails--rails/activerecord/CHANGELOG.md

• Add new error class TransactionTimeout for MySQL adapter which will be raised when lock wait time expires.

  Gabriel Courtemanche

• Remove deprecated #migration_keys.

  Ryuta Kamizono

• Automatically guess the inverse associations for STI.

  Yuichiro Kaneko

• Ensure sum honors distinct on has_many :through associations

  Fixes #16791.

  Aaron Wortham

• Add binary fixture helper method.

  Atsushi Yoshida

• When using Relation#or, extract the common conditions and put them before the OR condition.

  Maxime Handfield Lapointe

• Relation#or now accepts two relations who have different values for references only, as references can be implicitly called by where.

  Fixes #29411.

  Sean Griffin

• ApplicationRecord is no longer generated when generating models. If you need to generate it, it can be created with rails g application_record.

  Lisa Ugray

• Fix COUNT(DISTINCT ...) with ORDER BY and LIMIT to keep the existing select list.

  Ryuta Kamizono

• When a has_one association is destroyed by dependent: destroy, destroyed_by_association will now be set to the reflection, matching the behaviour of has_many associations.

  Lisa Ugray

• Fix unscoped(where: [columns]) removing the wrong bind values

  When the where is called on a relation after a or, unscoping the column of that later where removed bind values used by the or instead. (possibly other cases too)

  Post.where(id: 1).or(Post.where(id: 2)).where(foo: 3).unscope(where: :foo).to_sql
  # Currently:
  #     SELECT "posts".* FROM "posts" WHERE ("posts"."id" = 2 OR "posts"."id" = 3)
  # With fix:
  #     SELECT "posts".* FROM "posts" WHERE ("posts"."id" = 1 OR "posts"."id" = 2)
  

  Maxime Handfield Lapointe

• Values constructed using multi-parameter assignment will now use the post-type-cast value for rendering in single-field form inputs.

  Sean Griffin

• Relation#joins is no longer affected by the target model's current_scope, with the exception of unscoped.

  Fixes #29338.

  Sean Griffin

• Change sqlite3 boolean serialization to use 1 and 0

  SQLite natively recognizes 1 and 0 as true and false, but does not natively recognize 't' and 'f' as was previously serialized.

  This change in serialization requires a migration of stored boolean data for SQLite databases, so it's implemented behind a configuration flag whose default false value is deprecated.

  Lisa Ugray

• Skip query caching when working with batches of records (find_each, find_in_batches, in_batches).

  Previously, records would be fetched in batches, but all records would be retained in memory until the end of the request or job.

  Eugene Kenny

• Prevent errors raised by sql.active_record notification subscribers from being converted into ActiveRecord::StatementInvalid exceptions.

  Dennis Taylor

• Fix eager loading/preloading association with scope including joins.

  Fixes #28324.

  Ryuta Kamizono

• Fix transactions to apply state to child transactions

  Previously, if you had a nested transaction and the outer transaction was rolledback, the record from the inner transaction would still be marked as persisted.

  This change fixes that by applying the state of the parent transaction to the child transaction when the parent transaction is rolledback. This will correctly mark records from the inner transaction as not persisted.

  Eileen M. Uchitelle, Aaron Patterson

• Deprecate set_state method in TransactionState

  Deprecated the set_state method in favor of setting the state via specific methods. If you need to mark the state of the transaction you can now use rollback!, commit! or nullify! instead of set_state(:rolledback), set_state(:committed), or set_state(nil).

  Eileen M. Uchitelle, Aaron Patterson

• Deprecate delegating to arel in Relation.

  Ryuta Kamizono

• Fix eager loading to respect store_full_sti_class setting.

  Ryuta Kamizono

• Query cache was unavailable when entering the ActiveRecord::Base.cache block without being connected.

  Tsukasa Oishi

• Previously, when building records using a has_many :through association, if the child records were deleted before the parent was saved, they would still be persisted. Now, if child records are deleted before the parent is saved on a has_many :through association, the child records will not be persisted.

  Tobias Kraze

• Merging two relations representing nested joins no longer transforms the joins of the merged relation into LEFT OUTER JOIN. Example to clarify:

  Author.joins(:posts).merge(Post.joins(:comments))
  # Before the change:
  #=> SELECT ... FROM authors INNER JOIN posts ON ... LEFT OUTER JOIN comments ON...
  
  # After the change:
  #=> SELECT ... FROM authors INNER JOIN posts ON ... INNER JOIN comments ON...
  

  TODO: Add to the Rails 5.2 upgrade guide

  Maxime Handfield Lapointe

• ActiveRecord::Persistence#touch does not work well when optimistic locking enabled and locking_column, without default value, is null in the database.

  bogdanvlviv

• Fix destroying existing object does not work well when optimistic locking enabled and locking_column is null in the database.

  bogdanvlviv

• Use bulk INSERT to insert fixtures for better performance.

  Kir Shatrov

• Prevent creation of bind param if casted value is nil.

  Ryuta Kamizono

• Deprecate passing arguments and block at the same time to count and sum in ActiveRecord::Calculations.

  Ryuta Kamizono

• Loading model schema from database is now thread-safe.

  Fixes #28589.

  Vikrant Chaudhary, David Abdemoulaie

• Add ActiveRecord::Base#cache_version to support recyclable cache keys via the new versioned entries in ActiveSupport::Cache. This also means that ActiveRecord::Base#cache_key will now return a stable key that does not include a timestamp any more.

  NOTE: This feature is turned off by default, and #cache_key will still return cache keys with timestamps until you set ActiveRecord::Base.cache_versioning = true. That's the setting for all new apps on Rails 5.2+

  DHH

• Respect SchemaDumper.ignore_tables in rake tasks for databases structure dump

  Rusty Geldmacher, Guillermo Iguaran

• Add type caster to RuntimeReflection#alias_name

  Fixes #28959.

  Jon Moss

• Deprecate supports_statement_cache?.

  Ryuta Kamizono

• Quote database name in db:create grant statement (when database user does not have access to create the database).

  Rune Philosof

• Raise error UnknownMigrationVersionError on the movement of migrations when the current migration does not exist.

  bogdanvlviv

• Fix bin/rails db:forward first migration.

  bogdanvlviv

• Support Descending Indexes for MySQL.

  MySQL 8.0.1 and higher supports descending indexes: DESC in an index definition is no longer ignored. See https://dev.mysql.com/doc/refman/8.0/en/descending-indexes.html.

  Ryuta Kamizono

• Fix inconsistency with changed attributes when overriding AR attribute reader.

  bogdanvlviv

• When calling the dynamic fixture accessor method with no arguments, it now returns all fixtures of this type. Previously this method always returned an empty array.

  Kevin McPhillips

Please check 5-1-stable for previous changes.