CHANGELOG - rails 8.1.0 documentation

`Rails` 8.1.0 (October 22, 2025)¶ ↑

Remove deprecated passing a Time object to Time#since.

Rafael Mendonça França
Remove deprecated Benchmark.ms method. It is now defined in the benchmark gem.

Rafael Mendonça França
Remove deprecated addition for Time instances with ActiveSupport::TimeWithZone.

Rafael Mendonça França
Remove deprecated support for to_time to preserve the system local time. It will now always preserve the receiver timezone.

Rafael Mendonça França
Deprecate config.active_support.to_time_preserves_timezone.

Rafael Mendonça França
Standardize event name formatting in assert_event_reported error messages.

The event name in failure messages now uses .inspect (e.g., name: "user.created") to match assert_events_reported and provide type clarity between strings and symbols. This only affects tests that assert on the failure message format itself.

George Ma
Fix Enumerable#sole to return the full tuple instead of just the first element of the tuple.

Olivier Bellone
Fix parallel tests hanging when worker processes die abruptly.

Previously, if a worker process was killed (e.g., OOM killed, kill -9) during parallel test execution, the test suite would hang forever waiting for the dead worker.

Joshua Young
Add config.active_support.escape_js_separators_in_json.

Introduce a new framework default to skip escaping LINE SEPARATOR (U+2028) and PARAGRAPH SEPARATOR (U+2029) in JSON.

Historically these characters were not valid inside JavaScript literal strings but that changed in ECMAScript 2019. As such it’s no longer a concern in modern browsers: caniuse.com/mdn-javascript_builtins_json_json_superset.

Étienne Barrié, Jean Boussier
Fix NameError when class_attribute is defined on instance singleton classes.

Previously, calling class_attribute on an instance's singleton class would raise a NameError when accessing the attribute through the instance.
```
object = MyClass.new
object.singleton_class.class_attribute :foo, default: "bar"
object.foo # previously raised NameError, now returns "bar"
```
Joshua Young
Introduce ActiveSupport::Testing::EventReporterAssertions#with_debug_event_reporting to enable event reporter debug mode in tests.

The previous way to enable debug mode is by using with_debug on the event reporter itself, which is too verbose. This new helper will help clear up any confusion on how to test debug events.

Gannon McGibbon
Add ActiveSupport::StructuredEventSubscriber for consuming notifications and emitting structured event logs. Events may be emitted with the emit_event or emit_debug_event methods.
```
class MyStructuredEventSubscriber < ActiveSupport::StructuredEventSubscriber
  def notification(event)
    emit_event("my.notification", data: 1)
  end
end
```
Adrianna Chang
ActiveSupport::FileUpdateChecker does not depend on Time.now to prevent unecessary reloads with time travel test helpers

Jan Grodowski
Add ActiveSupport::Cache::Store#namespace= and namespace.

Can be used as an alternative to Store#clear in some situations such as parallel testing.

Nick Schwaderer
Create parallel_worker_id helper for running parallel tests. This allows users to know which worker they are currently running in.

Nick Schwaderer
Make the cache of ActiveSupport::Cache::Strategy::LocalCache::Middleware updatable.

If the cache client at Rails.cache of a booted application changes, the corresponding mounted middleware needs to update in order for request-local caches to be setup properly. Otherwise, redundant cache operations will erroneously hit the datastore.

Gannon McGibbon

Add assert_events_reported test helper for ActiveSupport::EventReporter.

This new assertion allows testing multiple events in a single block, regardless of order:

assert_events_reported([
  { name: "user.created", payload: { id: 123 } },
  { name: "email.sent", payload: { to: "user@example.com" } }
]) do
  create_user_and_send_welcome_email
end

George Ma

Add ActiveSupport::TimeZone#standard_name method.

zone = ActiveSupport::TimeZone['Hawaii']
# Old way
ActiveSupport::TimeZone::MAPPING[zone.name]
# New way
zone.standard_name # => 'Pacific/Honolulu'

Bogdan Gusiev

Add Structured Event Reporter, accessible via Rails.event.

The Event Reporter provides a unified interface for producing structured events in Rails applications:

Rails.event.notify("user.signup", user_id: 123, email: "user@example.com")

It supports adding tags to events:

Rails.event.tagged("graphql") do
  # Event includes tags: { graphql: true }
  Rails.event.notify("user.signup", user_id: 123, email: "user@example.com")
end

As well as context:

# All events will contain context: {request_id: "abc123", shop_id: 456}
Rails.event.set_context(request_id: "abc123", shop_id: 456)

Events are emitted to subscribers. Applications register subscribers to control how events are serialized and emitted. Subscribers must implement an emit method, which receives the event hash:

class LogSubscriber
  def emit(event)
    payload = event[:payload].map { |key, value| "#{key}=#{value}" }.join(" ")
    source_location = event[:source_location]
    log = "[#{event[:name]}] #{payload} at #{source_location[:filepath]}:#{source_location[:lineno]}"
    Rails.logger.info(log)
  end
end

Adrianna Chang

Make ActiveSupport::Logger freeze-friendly.

Joshua Young
Make ActiveSupport::Gzip.compress deterministic based on input.

ActiveSupport::Gzip.compress used to include a timestamp in the output, causing consecutive calls with the same input data to have different output if called during different seconds. It now always sets the timestamp to 0 so that the output is identical for any given input.

Rob Brackett
Given an array of Thread::Backtrace::Location objects, the new method ActiveSupport::BacktraceCleaner#clean_locations returns an array with the clean ones:
```
clean_locations = backtrace_cleaner.clean_locations(caller_locations)
```
Filters and silencers receive strings as usual. However, the path attributes of the locations in the returned array are the original, unfiltered ones, since locations are immutable.

Xavier Noria
Improve CurrentAttributes and ExecutionContext state managment in test cases.

Previously these two global state would be entirely cleared out whenever calling into code that is wrapped by the Rails executor, typically Action Controller or Active Job helpers:
```
test "#index works" do
  CurrentUser.id = 42
  get :index
  CurrentUser.id == nil
end
```
Now re-entering the executor properly save and restore that state.

Jean Boussier
The new method ActiveSupport::BacktraceCleaner#first_clean_location returns the first clean location of the caller's call stack, or nil. Locations are Thread::Backtrace::Location objects. Useful when you want to report the application-level location where something happened as an object.

Xavier Noria
FileUpdateChecker and EventedFileUpdateChecker ignore changes in Gem.path now.

Ermolaev Andrey, zzak
The new method ActiveSupport::BacktraceCleaner#first_clean_frame returns the first clean frame of the caller's backtrace, or nil. Useful when you want to report the application-level frame where something happened as a string.

Xavier Noria
Always clear CurrentAttributes instances.

Previously CurrentAttributes instance would be reset at the end of requests. Meaning its attributes would be re-initialized.

This is problematic because it assume these objects don't hold any state other than their declared attribute, which isn't always the case, and can lead to state leak across request.

Now CurrentAttributes instances are abandoned at the end of a request, and a new instance is created at the start of the next request.

Jean Boussier, Janko Marohnić
Add public API for before_fork_hook in parallel testing.

Introduces a public API for calling the before fork hooks implemented by parallel testing.
```
parallelize_before_fork do
    # perform an action before test processes are forked
end
```
Eileen M. Uchitelle
Implement ability to skip creating parallel testing databases.

With parallel testing, Rails will create a database per process. If this isn't desirable or you would like to implement databases handling on your own, you can now turn off this default behavior.

To skip creating a database per process, you can change it via the parallelize method:
```
parallelize(workers: 10, parallelize_databases: false)
```
or via the application configuration:
```
config.active_support.parallelize_databases = false
```
Eileen M. Uchitelle
Allow to configure maximum cache key sizes

When the key exceeds the configured limit (250 bytes by default), it will be truncated and the digest of the rest of the key appended to it.

Note that previously ActiveSupport::Cache::RedisCacheStore allowed up to 1kb cache keys before truncation, which is now reduced to 250 bytes.
```
config.cache_store = :redis_cache_store, { max_key_size: 64 }
```
fatkodima
Use UNLINK command instead of DEL in ActiveSupport::Cache::RedisCacheStore for non-blocking deletion.

Aron Roh

Add Cache#read_counter and Cache#write_counter

Rails.cache.write_counter("foo", 1)
Rails.cache.read_counter("foo") # => 1
Rails.cache.increment("foo")
Rails.cache.read_counter("foo") # => 2

Alex Ghiculescu

Introduce ActiveSupport::Testing::ErrorReporterAssertions#capture_error_reports

Captures all reported errors from within the block that match the given error class.

reports = capture_error_reports(IOError) do
  Rails.error.report(IOError.new("Oops"))
  Rails.error.report(IOError.new("Oh no"))
  Rails.error.report(StandardError.new)
end

assert_equal 2, reports.size
assert_equal "Oops", reports.first.error.message
assert_equal "Oh no", reports.last.error.message

Andrew Novoselac

Introduce ActiveSupport::ErrorReporter#add_middleware

When reporting an error, the error context middleware will be called with the reported error and base execution context. The stack may mutate the context hash. The mutated context will then be passed to error subscribers. Middleware receives the same parameters as ErrorReporter#report.

Andrew Novoselac, Sam Schmidt
Change execution wrapping to report all exceptions, including Exception.

If a more serious error like SystemStackError or NoMemoryError happens, the error reporter should be able to report these kinds of exceptions.

Gannon McGibbon
ActiveSupport::Testing::Parallelization.before_fork_hook allows declaration of callbacks that are invoked immediately before forking test workers.

Mike Dalessio

Allow the freeze_time testing helper to accept a date or time argument.

Time.current # => Sun, 09 Jul 2024 15:34:49 EST -05:00
freeze_time Time.current + 1.day
sleep 1
Time.current # => Mon, 10 Jul 2024 15:34:49 EST -05:00

Joshua Young

ActiveSupport::JSON now accepts options

It is now possible to pass options to ActiveSupport::JSON:
```
ActiveSupport::JSON.decode('{"key": "value"}', symbolize_names: true) # => { key: "value" }
```
matthaigh27

ActiveSupport::Testing::NotificationAssertions‘s assert_notification now matches against payload subsets by default.

Previously the following assertion would fail due to excess key vals in the notification payload. Now with payload subset matching, it will pass.

assert_notification("post.submitted", title: "Cool Post") do
  ActiveSupport::Notifications.instrument("post.submitted", title: "Cool Post", body: "Cool Body")
end

Additionally, you can now persist a matched notification for more customized assertions.

notification = assert_notification("post.submitted", title: "Cool Post") do
  ActiveSupport::Notifications.instrument("post.submitted", title: "Cool Post", body: Body.new("Cool Body"))
end

assert_instance_of(Body, notification.payload[:body])

Nicholas La Roux

Deprecate String#mb_chars and ActiveSupport::Multibyte::Chars.

These APIs are a relic of the Ruby 1.8 days when Ruby strings weren't encoding aware. There is no legitimate reasons to need these APIs today.

Jean Boussier
Deprecate ActiveSupport::Configurable

Sean Doyle
nil.to_query("key") now returns key.

Previously it would return key=, preventing round tripping with Rack::Utils.parse_nested_query.

Erol Fornoles
Avoid wrapping redis in a ConnectionPool when using ActiveSupport::Cache::RedisCacheStore if the :redis option is already a ConnectionPool.

Joshua Young
Alter ERB::Util.tokenize to return :PLAIN token with full input string when string doesn't contain ERB tags.

Martin Emde
Fix a bug in ERB::Util.tokenize that causes incorrect tokenization when ERB tags are preceded by multibyte characters.

Martin Emde
Add ActiveSupport::Testing::NotificationAssertions module to help with testing ActiveSupport::Notifications.

Nicholas La Roux, Yishu See, Sean Doyle
ActiveSupport::CurrentAttributes#attributes now will return a new hash object on each call.

Previously, the same hash object was returned each time that method was called.

fatkodima

ActiveSupport::JSON.encode supports CIDR notation.

Previously:

ActiveSupport::JSON.encode(IPAddr.new("172.16.0.0/24")) # => "\"172.16.0.0\""

After this change:

ActiveSupport::JSON.encode(IPAddr.new("172.16.0.0/24")) # => "\"172.16.0.0/24\""

Taketo Takashima

Make ActiveSupport::FileUpdateChecker faster when checking many file-extensions.

Jonathan del Strother

Please check 8-0-stable for previous changes.

Rails 8.1.0 (October 22, 2025)¶ ↑

`Rails` 8.1.0 (October 22, 2025)¶ ↑