Hi, this is Greg, bringing you this week’s changes in the Rails codebase.

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Prevent duplicate filters for encrypted attributes
When an Active Record encrypted attribute is declared, a filter for it is automatically added to config.filter_parameters. Prior to this pull request, the filter would be re-added every time the model was reloaded. This change ensures filters are only added once so that config.filter_parameters does not grow unbounded.

Prevent non-anonymous modules from becoming frozen
In 48106, Module#deep_dup was changed to return the module itself (not a copy) when the module is not anonymous. However, that causes non-anonymous modules to become frozen via value.deep_dup.freeze when passed to ActiveModel::Type::Helpers::Mutable#immutable_value. So, for example, class attributes can no longer be set on the module.
To prevent such issues, this pull request removes the freeze from immutable_value. immutable_value is only called by ActiveRecord::PredicateBuilder#build_bind_attribute, which only cares that other code cannot mutate the value, not that the value is actually frozen.

Allow PredicateBuilder to recognize schema namespaced table names
Before this change, ActiveRecord::PredicateBuilder assumed that a column name will only be specified in dot notation with a single period. If a column is specified in dot notation for a table that is namespaced in a schema, it used the schema name as the table name. This pull request allows columns to specified in the format schema.table.column as well as table.column.

Support :message_pack as cookies serializer
This commit adds support for :message_pack and :message_pack_allow_marshal as serializers for config.action_dispatch.cookies_serializer, just like config.active_support.message_serializer.

Support :message_pack as message serializer
This change adds support for :message_pack as a serializer for MessageEncryptor and MessageVerifier, and, consequently, as an option for config.active_support.message_serializer.

Default message serializer to :json_allow_marshal
This pull request changes the default message serializer set by config.load_defaults 7.1 from :json to :json_allow_marshal so that upgraded apps can continue to read old messages without additional configuration.
The intention is to eventually change the default to :json (with no Marshal fallback) in Rails 7.2, after some time has passed with apps generating JSON-serialized messages.
Apps can opt in to JSON-only serialization before Rails 7.2 by manually setting config.active_support.message_serializer = :json.

Handle empty list of cache keys
With this change, read_multi, write_multi and fetch_multi will bail out early if somehow called with an empty list.
The same change was done for delete_multi in a follow-up pull request.

Make increment_counter/decrement_counter accept an amount argument
This pull request introduces the by option to increment_counter and decrement_counter to make it easier to change counters by an arbitrary value. Example usage:

Company.increment_counter(:users_count, 5, by: 3)

Make Active Record’s query cache an LRU
Active Record query cache is now evicts least recently used entries, with 100 entries as a default. The cache size can be configured via database.yml

development:
  adapter: mysql2
  query_cache: 100

It can also be entirely disabled:

development:
  adapter: mysql2
  query_cache: false

Add a picture_tag helper
This pull request adds support for the HTML picture tag. It supports passing a String, an Array or a Block and passing properties directly to the img tag via the :image key.
Since the picture tag requires an img tag, the last element you provide will be used for the img tag.
For complete control over the picture tag, a block can be passed, which will populate the contents of the tag accordingly. See the pull request for usage examples.

Add matcher support to assert_enqueued_email_with
Currently, assert_enqueued_with allows you to pass procs for matching args. However, assert_enqueued_email_with doesn’t let you do that for args and params.
This pull request made assert_enqueued_email_with accept procs for args and params:

assert_enqueued_email_with DeliveryJob, params: -> p { p[:token] =~ /\w+/ } do
  UserMailer.with(token: user.generate_token).email_verification.deliver_later
end

Until next time!