rails--rails/activerecord/CHANGELOG.md

• Use an empty query to check if the PostgreSQL connection is still active

  An empty query is faster than SELECT 1.

  Heinrich Lee Yu

• Add ActiveRecord::Base#previously_persisted?

  Returns true if the object has been previously persisted but now it has been deleted.

• Deprecate partial_writes in favor of partial_inserts and partial_updates.

  This allows to have a different behavior on update and create.

  Jean Boussier

• Fix compatibility with psych >= 4.

  Starting in Psych 4.0.0 YAML.load behaves like YAML.safe_load. To preserve compatibility Active Record's schema cache loader and YAMLColumn now uses YAML.unsafe_load if available.

  Jean Boussier

• ActiveRecord::Base.logger is now a class_attribute.

  This means it can no longer be accessed directly through @@logger, and that setting logger = on a subclass won't change the parent's logger.

  Jean Boussier

• Add .asc.nulls_first for all databases. Unfortunately MySQL still doesn't like nulls_last.

  Keenan Brock

• Improve performance of one? and many? by limiting the generated count query to 2 results.

  Gonzalo Riestra

• Don't check type when using if_not_exists on add_column.

  Previously, if a migration called add_column with the if_not_exists option set to true the column_exists? check would look for a column with the same name and type as the migration.

  Recently it was discovered that the type passed to the migration is not always the same type as the column after migration. For example a column set to :mediumblob in the migration will be casted to binary when calling column.type. Since there is no straightforward way to cast the type to the database type without running the migration, we opted to drop the type check from add_column. This means that migrations adding a duplicate column with a different type will no longer raise an error.

  Eileen M. Uchitelle

• Log a warning message when running SQLite in production

  Using SQLite in production ENV is generally discouraged. SQLite is also the default adapter in a new Rails application. For the above reasons log a warning message when running SQLite in production.

  The warning can be disabled by setting config.active_record.sqlite3_production_warning=false.

  Jacopo Beschi

• Add option to disable joins for has_one associations.

  In a multiple database application, associations can't join across databases. When set, this option instructs Rails to generate 2 or more queries rather than generating joins for has_one associations.

  Set the option on a has one through association:

  class Person
    belongs_to :dog
    has_one :veterinarian, through: :dog, disable_joins: true
  end
  

  Then instead of generating join SQL, two queries are used for @person.veterinarian:

  SELECT "dogs"."id" FROM "dogs" WHERE "dogs"."person_id" = ?  [["person_id", 1]]
  SELECT "veterinarians".* FROM "veterinarians" WHERE "veterinarians"."dog_id" = ?  [["dog_id", 1]]
  

  Sarah Vessels, Eileen M. Uchitelle

• Arel::Visitors::Dot now renders a complete set of properties when visiting Arel::Nodes::SelectCore, SelectStatement, InsertStatement, UpdateStatement, and DeleteStatement, which fixes #42026. Previously, some properties were omitted.

  Mike Dalessio

• Arel::Visitors::Dot now supports Arel::Nodes::Bin, Case, CurrentRow, Distinct, DistinctOn, Else, Except, InfixOperation, Intersect, Lock, NotRegexp, Quoted, Regexp, UnaryOperation, Union, UnionAll, When, and With. Previously, these node types caused an exception to be raised by Arel::Visitors::Dot#accept.

  Mike Dalessio

• Optimize remove_columns to use a single SQL statement.

  remove_columns :my_table, :col_one, :col_two
  

  Now results in the following SQL:

  ALTER TABLE "my_table" DROP COLUMN "col_one", DROP COLUMN "col_two"
  

  Jon Dufresne

• Ensure has_one autosave association callbacks get called once.

  Change the has_one autosave callback to be non cyclic as well. By doing this the autosave callback are made more consistent for all 3 cases: has_many, has_one, and belongs_to.

  Petrik de Heus

• Add option to disable joins for associations.

  In a multiple database application, associations can't join across databases. When set, this option instructs Rails to generate 2 or more queries rather than generating joins for associations.

  Set the option on a has many through association:

  class Dog
    has_many :treats, through: :humans, disable_joins: true
    has_many :humans
  end
  

  Then instead of generating join SQL, two queries are used for @dog.treats:

  SELECT "humans"."id" FROM "humans" WHERE "humans"."dog_id" = ?  [["dog_id", 1]]
  SELECT "treats".* FROM "treats" WHERE "treats"."human_id" IN (?, ?, ?)  [["human_id", 1], ["human_id", 2], ["human_id", 3]]
  

  Eileen M. Uchitelle, Aaron Patterson, Lee Quarella

• Add setting for enumerating column names in SELECT statements.

  Adding a column to a PostgreSQL database, for example, while the application is running can change the result of wildcard SELECT * queries, which invalidates the result of cached prepared statements and raises a PreparedStatementCacheExpired error.

  When enabled, Active Record will avoid wildcards and always include column names in SELECT queries, which will return consistent results and avoid prepared statement errors.

  Before:

  Book.limit(5)
  # SELECT * FROM books LIMIT 5
  

  After:

  # config/application.rb
  module MyApp
    class Application < Rails::Application
      config.active_record.enumerate_columns_in_select_statements = true
    end
  end
  
  # or, configure per-model
  class Book < ApplicationRecord
    self.enumerate_columns_in_select_statements = true
  end
  

  Book.limit(5)
  # SELECT id, author_id, name, format, status, language, etc FROM books LIMIT 5
  

  Matt Duszynski

• Allow passing SQL as on_duplicate value to #upsert_all to make it possible to use raw SQL to update columns on conflict:

  Book.upsert_all(
    [{ id: 1, status: 1 }, { id: 2, status: 1 }],
    on_duplicate: Arel.sql("status = GREATEST(books.status, EXCLUDED.status)")
  )
  

  Vladimir Dementyev

• Allow passing SQL as returning statement to #upsert_all:

  Article.insert_all(
  [
      { title: "Article 1", slug: "article-1", published: false },
      { title: "Article 2", slug: "article-2", published: false }
    ],
    returning: Arel.sql("id, (xmax = '0') as inserted, name as new_name")
  )
  

  Vladimir Dementyev

• Deprecate legacy_connection_handling.

  Eileen M. Uchitelle

• Add attribute encryption support.

  Encrypted attributes are declared at the model level. These are regular Active Record attributes backed by a column with the same name. The system will transparently encrypt these attributes before saving them into the database and will decrypt them when retrieving their values.

  class Person < ApplicationRecord
    encrypts :name
    encrypts :email_address, deterministic: true
  end
  

  You can learn more in the Active Record Encryption guide.

  Jorge Manrubia

• Changed Arel predications contains and overlaps to use quoted_node so that PostgreSQL arrays are quoted properly.

  Bradley Priest

• Add mode argument to record level strict_loading!

  This argument can be used when enabling strict loading for a single record to specify that we only want to raise on n plus one queries.

  developer.strict_loading!(mode: :n_plus_one_only)
  
  developer.projects.to_a # Does not raise
  developer.projects.first.client # Raises StrictLoadingViolationError
  

  Previously, enabling strict loading would cause any lazily loaded association to raise an error. Using n_plus_one_only mode allows us to lazily load belongs_to, has_many, and other associations that are fetched through a single query.

  Dinah Shi

• Fix Float::INFINITY assignment to datetime column with postgresql adapter

  Before:

  # With this config
  ActiveRecord::Base.time_zone_aware_attributes = true
  
  # and the following schema:
  create_table "postgresql_infinities" do |t|
    t.datetime "datetime"
  end
  
  # This test fails
  record = PostgresqlInfinity.create!(datetime: Float::INFINITY)
  assert_equal Float::INFINITY, record.datetime # record.datetime gets nil
  

  After this commit, record.datetime gets Float::INFINITY as expected.

  Shunichi Ikegami

• Type cast enum values by the original attribute type.

  The notable thing about this change is that unknown labels will no longer match 0 on MySQL.

  class Book < ActiveRecord::Base
    enum :status, { proposed: 0, written: 1, published: 2 }
  end
  

  Before:

  # SELECT `books`.* FROM `books` WHERE `books`.`status` = 'prohibited' LIMIT 1
  Book.find_by(status: :prohibited)
  # => #<Book id: 1, status: "proposed", ...> (for mysql2 adapter)
  # => ActiveRecord::StatementInvalid: PG::InvalidTextRepresentation: ERROR:  invalid input syntax for type integer: "prohibited" (for postgresql adapter)
  # => nil (for sqlite3 adapter)
  

  After:

  # SELECT `books`.* FROM `books` WHERE `books`.`status` IS NULL LIMIT 1
  Book.find_by(status: :prohibited)
  # => nil (for all adapters)
  

  Ryuta Kamizono

• Fixtures for has_many :through associations now load timestamps on join tables

  Given this fixture:

  ### monkeys.yml
  george:
    name: George the Monkey
    fruits: apple
  
  ### fruits.yml
  apple:
    name: apple
  

  If the join table (fruit_monkeys) contains created_at or updated_at columns, these will now be populated when loading the fixture. Previously, fixture loading would crash if these columns were required, and leave them as null otherwise.

  Alex Ghiculescu

• Allow applications to configure the thread pool for async queries

  Some applications may want one thread pool per database whereas others want to use a single global thread pool for all queries. By default, Rails will set async_query_executor to nil which will not initialize any executor. If load_async is called and no executor has been configured, the query will be executed in the foreground.

  To create one thread pool for all database connections to use applications can set config.active_record.async_query_executor to :global_thread_pool and optionally define config.active_record.global_executor_concurrency. This defaults to 4. For applications that want to have a thread pool for each database connection, config.active_record.async_query_executor can be set to :multi_thread_pool. The configuration for each thread pool is set in the database configuration.

  Eileen M. Uchitelle

• Allow new syntax for enum to avoid leading _ from reserved options.

  Before:

  class Book < ActiveRecord::Base
    enum status: [ :proposed, :written ], _prefix: true, _scopes: false
    enum cover: [ :hard, :soft ], _suffix: true, _default: :hard
  end
  

  After:

  class Book < ActiveRecord::Base
    enum :status, [ :proposed, :written ], prefix: true, scopes: false
    enum :cover, [ :hard, :soft ], suffix: true, default: :hard
  end
  

  Ryuta Kamizono

• Add ActiveRecord::Relation#load_async.

  This method schedules the query to be performed asynchronously from a thread pool.

  If the result is accessed before a background thread had the opportunity to perform the query, it will be performed in the foreground.

  This is useful for queries that can be performed long enough before their result will be needed, or for controllers which need to perform several independent queries.

  def index
    @categories = Category.some_complex_scope.load_async
    @posts = Post.some_complex_scope.load_async
  end
  

  Jean Boussier

• Implemented ActiveRecord::Relation#excluding method.

  This method excludes the specified record (or collection of records) from the resulting relation:

  Post.excluding(post)
  Post.excluding(post_one, post_two)
  

  Also works on associations:

  post.comments.excluding(comment)
  post.comments.excluding(comment_one, comment_two)
  

  This is short-hand for Post.where.not(id: post.id) (for a single record) and Post.where.not(id: [post_one.id, post_two.id]) (for a collection).

  Glen Crawford

• Skip optimised #exist? query when #include? is called on a relation with a having clause

  Relations that have aliased select values AND a having clause that references an aliased select value would generate an error when #include? was called, due to an optimisation that would generate call #exists? on the relation instead, which effectively alters the select values of the query (and thus removes the aliased select values), but leaves the having clause intact. Because the having clause is then referencing an aliased column that is no longer present in the simplified query, an ActiveRecord::InvalidStatement error was raised.

  A sample query affected by this problem:

  Author.select('COUNT(*) as total_posts', 'authors.*')
        .joins(:posts)
        .group(:id)
        .having('total_posts > 2')
        .include?(Author.first)
  

  This change adds an addition check to the condition that skips the simplified #exists? query, which simply checks for the presence of a having clause.

  Fixes #41417

  Michael Smart

• Increment postgres prepared statement counter before making a prepared statement, so if the statement is aborted without Rails knowledge (e.g., if app gets killed during long-running query or due to Rack::Timeout), app won't end up in perpetual crash state for being inconsistent with Postgres.

  wbharding, Martin Tepper

• Add ability to apply scoping to all_queries.

  Some applications may want to use the scoping method but previously it only worked on certain types of queries. This change allows the scoping method to apply to all queries for a model in a block.

  Post.where(blog_id: post.blog_id).scoping(all_queries: true) do
    post.update(title: "a post title") # adds `posts.blog_id = 1` to the query
  end
  

  Eileen M. Uchitelle

• ActiveRecord::Calculations.calculate called with :average (aliased as ActiveRecord::Calculations.average) will now use column based type casting. This means that floating-point number columns will now be aggregated as Float and decimal columns will be aggregated as BigDecimal.

  Integers are handled as a special case returning BigDecimal always (this was the case before already).

  # With the following schema:
  create_table "measurements" do |t|
    t.float "temperature"
  end
  
  # Before:
  Measurement.average(:temperature).class
  # => BigDecimal
  
  # After:
  Measurement.average(:temperature).class
  # => Float
  

  Before this change, Rails just called to_d on average aggregates from the database adapter. This is not the case anymore. If you relied on that kind of magic, you now need to register your own ActiveRecord::Type (see ActiveRecord::Attributes::ClassMethods for documentation).

  Josua Schmid

• PostgreSQL: introduce ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.datetime_type

  This setting controls what native type Active Record should use when you call datetime in a migration or schema. It takes a symbol which must correspond to one of the configured NATIVE_DATABASE_TYPES. The default is :timestamp, meaning t.datetime in a migration will create a "timestamp without time zone" column. To use "timestamp with time zone", change this to :timestamptz in an initializer.

  You should run bin/rails db:migrate to rebuild your schema.rb if you change this.

  Alex Ghiculescu

• PostgreSQL: handle timestamp with time zone columns correctly in schema.rb.

  Previously they dumped as t.datetime :column_name, now they dump as t.timestamptz :column_name, and are created as timestamptz columns when the schema is loaded.

  Alex Ghiculescu

• Removing trailing whitespace when matching columns in ActiveRecord::Sanitization.disallow_raw_sql!.

  Gannon McGibbon, Adrian Hirt

• Expose a way for applications to set a primary_abstract_class

  Multiple database applications that use a primary abstract class that is not named ApplicationRecord can now set a specific class to be the primary_abstract_class.

  class PrimaryApplicationRecord
    self.primary_abstract_class
  end
  

  When an application boots it automatically connects to the primary or first database in the database configuration file. In a multiple database application that then call connects_to needs to know that the default connection is the same as the ApplicationRecord connection. However, some applications have a differently named ApplicationRecord. This prevents Active Record from opening duplicate connections to the same database.

  Eileen M. Uchitelle, John Crepezzi

• Support hash config for structure_dump_flags and structure_load_flags flags Now that Active Record supports multiple databases configuration we need a way to pass specific flags for dump/load databases since the options are not the same for different adapters. We can use in the original way:

  ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = ['--no-defaults', '--skip-add-drop-table']
  #or
  ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = '--no-defaults --skip-add-drop-table'
  

  And also use it passing a hash, with one or more keys, where the key is the adapter

  ActiveRecord::Tasks::DatabaseTasks.structure_dump_flags = {
    mysql2: ['--no-defaults', '--skip-add-drop-table'],
    postgres: '--no-tablespaces'
  }
  

  Gustavo Gonzalez

• Connection specification now passes the "url" key as a configuration for the adapter if the "url" protocol is "jdbc", "http", or "https". Previously only urls with the "jdbc" prefix were passed to the Active Record Adapter, others are assumed to be adapter specification urls.

  Fixes #41137.

  Jonathan Bracy

• Allow to opt-out of strict_loading mode on a per-record base.

  This is useful when strict loading is enabled application wide or on a model level.

  class User < ApplicationRecord
    has_many :bookmarks
    has_many :articles, strict_loading: true
  end
  
  user = User.first
  user.articles                        # => ActiveRecord::StrictLoadingViolationError
  user.bookmarks                       # => #<ActiveRecord::Associations::CollectionProxy>
  
  user.strict_loading!(true)           # => true
  user.bookmarks                       # => ActiveRecord::StrictLoadingViolationError
  
  user.strict_loading!(false)          # => false
  user.bookmarks                       # => #<ActiveRecord::Associations::CollectionProxy>
  user.articles.strict_loading!(false) # => #<ActiveRecord::Associations::CollectionProxy>
  

  Ayrton De Craene

• Add FinderMethods#sole and #find_sole_by to find and assert the presence of exactly one record.

  Used when you need a single row, but also want to assert that there aren't multiple rows matching the condition; especially for when database constraints aren't enough or are impractical.

  Product.where(["price = %?", price]).sole
  # => ActiveRecord::RecordNotFound      (if no Product with given price)
  # => #<Product ...>                    (if one Product with given price)
  # => ActiveRecord::SoleRecordExceeded  (if more than one Product with given price)
  
  user.api_keys.find_sole_by(key: key)
  # as above
  

  Asherah Connor

• Makes ActiveRecord::AttributeMethods::Query respect the getter overrides defined in the model.

  Before:

  class User
    def admin
      false # Overriding the getter to always return false
    end
  end
  
  user = User.first
  user.update(admin: true)
  
  user.admin # false (as expected, due to the getter overwrite)
  user.admin? # true (not expected, returned the DB column value)
  

  After this commit, user.admin? above returns false, as expected.

  Fixes #40771.

  Felipe

• Allow delegated_type to be specified primary_key and foreign_key.

  Since delegated_type assumes that the foreign_key ends with _id, singular_id defined by it does not work when the foreign_key does not end with id. This change fixes it by taking into account primary_key and foreign_key in the options.

  Ryota Egusa

• Expose an invert_where method that will invert all scope conditions.

  class User
    scope :active, -> { where(accepted: true, locked: false) }
  end
  
  User.active
  # ... WHERE `accepted` = 1 AND `locked` = 0
  
  User.active.invert_where
  # ... WHERE NOT (`accepted` = 1 AND `locked` = 0)
  

  Kevin Deisz

• Restore possibility of passing false to :polymorphic option of belongs_to.

  Previously, passing false would trigger the option validation logic to throw an error saying :polymorphic would not be a valid option.

  glaszig

• Remove deprecated database kwarg from connected_to.

  Eileen M. Uchitelle, John Crepezzi

• Allow adding nonnamed expression indexes to be revertible.

  Fixes #40732.

  Previously, the following code would raise an error, when executed while rolling back, and the index name should be specified explicitly. Now, the index name is inferred automatically.

  add_index(:items, "to_tsvector('english', description)")
  

  fatkodima

• Only warn about negative enums if a positive form that would cause conflicts exists.

  Fixes #39065.

  Alex Ghiculescu

• Add option to run default_scope on all queries.

  Previously, a default_scope would only run on select or insert queries. In some cases, like non-Rails tenant sharding solutions, it may be desirable to run default_scope on all queries in order to ensure queries are including a foreign key for the shard (i.e. blog_id).

  Now applications can add an option to run on all queries including select, insert, delete, and update by adding an all_queries option to the default scope definition.

  class Article < ApplicationRecord
    default_scope -> { where(blog_id: Current.blog.id) }, all_queries: true
  end
  

  Eileen M. Uchitelle

• Add where.associated to check for the presence of an association.

  # Before:
  account.users.joins(:contact).where.not(contact_id: nil)
  
  # After:
  account.users.where.associated(:contact)
  

  Also mirrors where.missing.

  Kasper Timm Hansen

• Allow constructors (build_association and create_association) on has_one :through associations.

  Santiago Perez Perret

Please check 6-1-stable for previous changes.