Ruby on Rails 6.1 Release Notes

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.

1. Upgrading to Rails 6.1

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.

2. Major Features

2.1. Per-database Connection Switching

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.

2.2. Horizontal Sharding

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.

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.

Remove deprecated ActionDispatch::Http::ParameterFilter.
Remove deprecated force_ssl at the controller level.

5.2. Deprecations

Deprecate config.action_dispatch.return_only_media_type_on_content_type.

5.3. Notable changes

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

6. Action View

Please refer to the Changelog for detailed changes.

6.1. Removals

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.

6.2. Deprecations

6.3. Notable changes

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.

7. Action Mailer

Please refer to the Changelog for detailed changes.

7.1. Removals

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

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.

8.2. Deprecations

Deprecate ActiveRecord::Base.allow_unsafe_raw_sql.
Deprecate database kwarg on connected_to.
Deprecate connection_handlers when legacy_connection_handling is set to false.

8.3. Notable changes

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.

9. Active Storage

Please refer to the Changelog for detailed changes.

9.1. Removals

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.

9.2. Deprecations

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

9.3. Notable changes

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.

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.

11. Active Support

Please refer to the Changelog for detailed changes.

11.1. Removals

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=.

11.2. Deprecations

Deprecate ActiveSupport::Multibyte::Unicode.default_normalization_form.

Deprecate config.active_job.return_false_on_aborted_enqueue.

12.3. Notable changes

Return false when enqueuing a job is aborted.

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)

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.