Version 6.1 - December 2020

Highlights in Rails 6.1:

• Per-database Connection Switching
• Horizontal Sharding
• Strict Loading Associations
• Delegated Types
• Destroy Associations Async

These release notes cover only the major changes. To learn about various bug fixes and changes, please refer to the changelogs or check out the list of commits in the main Rails repository on GitHub.

If you’re upgrading an existing application, it’s a great idea to have good test coverage before going in. You should also first upgrade to Rails 6.0 in case you haven’t and make sure your application still runs as expected before attempting an update to Rails 6.1. A list of things to watch out for when upgrading is available in the Upgrading Ruby on Rails guide.

Rails 6.1 provides you with the ability to switch connections per-database. In 6.0 if you switched to the reading role then all database connections also switched to the reading role. Now in 6.1 if you set legacy_connection_handling to false in your configuration, Rails will allow you to switch connections for a single database by calling connected_to on the corresponding abstract class.

Rails 6.0 provided the ability to functionally partition (multiple partitions, different schemas) your database but wasn’t able to support horizontal sharding (same schema, multiple partitions). Rails wasn’t able to support horizontal sharding because models in Active Record could only have one connection per-role per-class. This is now fixed and horizontal sharding with Rails is available.

Strict loading associations allows you to ensure that all your associations are loaded eagerly and stop N+1’s before they happen.

Delegated Types is an alternative to single-table inheritance. This helps represent class hierarchies allowing the superclass to be a concrete class that is represented by its own table. Each subclass has its own table for additional attributes.

Destroy associations async adds the ability for applications to destroy associations in a background job. This can help you avoid timeouts and other performance issues in your application when destroying data.

Please refer to the Changelog for detailed changes.

• Remove deprecated rake notes tasks.

• Remove deprecated connection option in the rails dbconsole command.

• Remove deprecated SOURCE_ANNOTATION_DIRECTORIES environment variable support from rails notes.

• Remove deprecated server argument from the rails server command.

• Remove deprecated support for using the HOST environment variable to specify the server IP.

• Remove deprecated rake dev:cache tasks.

• Remove deprecated rake routes tasks.

• Remove deprecated rake initializers tasks.

Please refer to the Changelog for detailed changes.

Please refer to the Changelog for detailed changes.

• Remove deprecated ActionDispatch::Http::ParameterFilter.

• Remove deprecated force_ssl at the controller level.

• Deprecate config.action_dispatch.return_only_media_type_on_content_type.

• Change ActionDispatch::Response#content_type to return the full Content-Type header.

Please refer to the Changelog for detailed changes.

• Remove deprecated escape_whitelist from ActionView::Template::Handlers::ERB.

• Remove deprecated find_all_anywhere from ActionView::Resolver.

• Remove deprecated formats from ActionView::Template::HTML.

• Remove deprecated formats from ActionView::Template::RawFile.

• Remove deprecated formats from ActionView::Template::Text.

• Remove deprecated find_file from ActionView::PathSet.

• Remove deprecated rendered_format from ActionView::LookupContext.

• Remove deprecated find_file from ActionView::ViewPaths.

• Remove deprecated support to pass an object that is not a ActionView::LookupContext as the first argument in ActionView::Base#initialize.

• Remove deprecated format argument ActionView::Base#initialize.

• Remove deprecated ActionView::Template#refresh.

• Remove deprecated ActionView::Template#original_encoding.

• Remove deprecated ActionView::Template#variants.

• Remove deprecated ActionView::Template#formats.

• Remove deprecated ActionView::Template#virtual_path=.

• Remove deprecated ActionView::Template#updated_at.

• Remove deprecated updated_at argument required on ActionView::Template#initialize.

• Remove deprecated ActionView::Template.finalize_compiled_template_methods.

• Remove deprecated config.action_view.finalize_compiled_template_methods

• Remove deprecated support to calling ActionView::ViewPaths#with_fallback with a block.

• Remove deprecated support to passing absolute paths to render template:.

• Remove deprecated support to passing relative paths to render file:.

• Remove support to template handlers that don’t accept two arguments.

• Remove deprecated pattern argument in ActionView::Template::PathResolver.

• Remove deprecated support to call private methods from object in some view helpers.

• Require that ActionView::Base subclasses implement #compiled_method_container.

• Make locals argument required on ActionView::Template#initialize.

• The javascript_include_tag and stylesheet_link_tag asset helpers generate a Link header that gives hints to modern browsers about preloading assets. This can be disabled by setting config.action_view.preload_links_header to false.

Please refer to the Changelog for detailed changes.

• Remove deprecated ActionMailer::Base.receive in favor of Action Mailbox.

Please refer to the Changelog for detailed changes.

• Remove deprecated methods from ActiveRecord::ConnectionAdapters::DatabaseLimits.

  column_name_length table_name_length columns_per_table indexes_per_table columns_per_multicolumn_index sql_query_length joins_per_query

• Remove deprecated ActiveRecord::ConnectionAdapters::AbstractAdapter#supports_multi_insert?.

• Remove deprecated ActiveRecord::ConnectionAdapters::AbstractAdapter#supports_foreign_keys_in_create?.

• Remove deprecated ActiveRecord::ConnectionAdapters::PostgreSQLAdapter#supports_ranges?.

• Remove deprecated ActiveRecord::Base#update_attributes and ActiveRecord::Base#update_attributes!.

• Remove deprecated migrations_path argument in ActiveRecord::ConnectionAdapter::SchemaStatements#assume_migrated_upto_version.

• Remove deprecated config.active_record.sqlite3.represent_boolean_as_integer.

• Remove deprecated methods from ActiveRecord::DatabaseConfigurations.

  fetch each first values []=

• Remove deprecated ActiveRecord::Result#to_hash method.

• Remove deprecated support for using unsafe raw SQL in ActiveRecord::Relation methods.

• Deprecate ActiveRecord::Base.allow_unsafe_raw_sql.

• Deprecate database kwarg on connected_to.

• Deprecate connection_handlers when legacy_connection_handling is set to false.

• MySQL: Uniqueness validator now respects default database collation, no longer enforce case-sensitive comparison by default.

• relation.create does no longer leak scope to class-level querying methods in initialization block and callbacks.

  Before:

  User.where(name: "John").create do |john|
    User.find_by(name: "David") # => nil
  end
  

  After:

  User.where(name: "John").create do |john|
    User.find_by(name: "David") # => #<User name: "David", ...>
  end
  

• Named scope chain does no longer leak scope to class-level querying methods.

  class User < ActiveRecord::Base
    scope :david, -> { User.where(name: "David") }
  end
  

  Before:

  User.where(name: "John").david
  # SELECT * FROM users WHERE name = 'John' AND name = 'David'
  

  After:

  User.where(name: "John").david
  # SELECT * FROM users WHERE name = 'David'
  

• where.not now generates NAND predicates instead of NOR.

  Before:

  User.where.not(name: "Jon", role: "admin")
  # SELECT * FROM users WHERE name != 'Jon' AND role != 'admin'
  

  After:

  User.where.not(name: "Jon", role: "admin")
  # SELECT * FROM users WHERE NOT (name == 'Jon' AND role == 'admin')
  

• To use the new per-database connection handling applications must change legacy_connection_handling to false and remove deprecated accessors on connection_handlers. Public methods for connects_to and connected_to require no changes.

Please refer to the Changelog for detailed changes.

• Remove deprecated support to pass :combine_options operations to ActiveStorage::Transformers::ImageProcessing.

• Remove deprecated ActiveStorage::Transformers::MiniMagickTransformer.

• Remove deprecated config.active_storage.queue.

• Remove deprecated ActiveStorage::Downloading.

• Deprecate Blob.create_after_upload in favor of Blob.create_and_upload. (Pull Request)

• Add Blob.create_and_upload to create a new blob and upload the given io to the service. (Pull Request)
• ActiveStorage::Blob#service_name column was added. It is required that a migration is run after the upgrade. Run bin/rails app:update to generate that migration.

Please refer to the Changelog for detailed changes.

• Active Model’s errors are now objects with an interface that allows your application to more easily handle and interact with errors thrown by models. The feature includes a query interface, enables more precise testing, and access to error details.

Please refer to the Changelog for detailed changes.

• Remove deprecated fallback to I18n.default_locale when config.i18n.fallbacks is empty.

• Remove deprecated LoggerSilence constant.

• Remove deprecated ActiveSupport::LoggerThreadSafeLevel#after_initialize.

• Remove deprecated Module#parent_name, Module#parent and Module#parents.

• Remove deprecated file active_support/core_ext/module/reachable.

• Remove deprecated file active_support/core_ext/numeric/inquiry.

• Remove deprecated file active_support/core_ext/array/prepend_and_append.

• Remove deprecated file active_support/core_ext/hash/compact.

• Remove deprecated file active_support/core_ext/hash/transform_values.

• Remove deprecated file active_support/core_ext/range/include_range.

• Remove deprecated ActiveSupport::Multibyte::Chars#consumes? and ActiveSupport::Multibyte::Chars#normalize.

• Remove deprecated ActiveSupport::Multibyte::Unicode.pack_graphemes, ActiveSupport::Multibyte::Unicode.unpack_graphemes, ActiveSupport::Multibyte::Unicode.normalize, ActiveSupport::Multibyte::Unicode.downcase, ActiveSupport::Multibyte::Unicode.upcase and ActiveSupport::Multibyte::Unicode.swapcase.

• Remove deprecated ActiveSupport::Notifications::Instrumenter#end=.

• Deprecate ActiveSupport::Multibyte::Unicode.default_normalization_form.

Please refer to the Changelog for detailed changes.

• Deprecate config.active_job.return_false_on_aborted_enqueue.

• Return false when enqueuing a job is aborted.

Please refer to the Changelog for detailed changes.

• Add method to confirm rich text content existence by adding ? after name of the rich text attribute. (Pull Request)

• Add fill_in_rich_text_area system test case helper to find a trix editor and fill it with given HTML content. (Pull Request)

• Add ActionText::FixtureSet.attachment to generate <action-text-attachment> elements in database fixtures. (Pull Request)

Please refer to the Changelog for detailed changes.

• Deprecate Rails.application.credentials.action_mailbox.api_key and MAILGUN_INGRESS_API_KEY in favor of Rails.application.credentials.action_mailbox.signing_key and MAILGUN_INGRESS_SIGNING_KEY.

Please refer to the Changelog for detailed changes.

See the full list of contributors to Rails for the many people who spent many hours making Rails, the stable and robust framework it is. Kudos to all of them.