Instantiate validators at definition time

[ericproulx]

Instantiate validators at definition time

Summary

Validators are now instantiated at definition time (in ParamsScope and ContractScope) rather than at request time via ValidatorFactory. This eliminates per-request object allocation overhead and allows expensive setup (option parsing, converter building) to happen once.

I18n translation is handled through a shared Grape::Util::Translation module. Validators that need interpolation parameters (e.g. LengthValidator, SameAsValidator) store a Hash { key: :length, min: 2, max: 5 } as their message. Exceptions::Base#translate_message dispatches on type — Symbol, Hash, Proc, or String — so translation with the correct locale always happens at error-raise time.

Changes

Shared translation module (Grape::Util::Translation)

• Extracted translate (with fallback locale logic) into Grape::Util::Translation, included by both Exceptions::Base and Validators::Base
• Removed FALLBACK_LOCALE, translate, and fallback_message from Exceptions::Base
• Exceptions::Base#translate_message and translate_attributes delegate to translate with a scope: parameter
• Exceptions::Base#translate_message now supports Hash messages: { key: :symbol, **interpolation_params } for deferred translation with interpolation
• Validators::Base#translate_message delegates to translate with the grape.errors.messages scope

Core architecture

• ParamsScope#validate and ContractScope now store validator instances instead of option hashes in namespace_stackable[:validations]
• ParamsScope#coerce_type receives validations.extract!(:coerce, :coerce_with, :coerce_message) instead of the full hash, replacing the individual delete calls that followed
• Endpoint#run_validators takes a request: keyword arg, reads validators directly from inheritable_setting.route[:saved_validations], and short-circuits with return if validators.blank?
• Removed Endpoint#validations enumerator method
• Removed ValidatorFactory

Validator base (Validators::Base)

• fail_fast? is now an explicit public method
• Moved validate!, message, options_key? to private
• options_key? simplified to a single key parameter
• Added private helpers: hash_like?, option_value, scrub, translate_message
• message accepts a block for lazy default generation, returns key when present
• @fail_fast, @allow_blank = opts.values_at(:fail_fast, :allow_blank) in constructor

Validator optimizations — eagerly compute in initialize

• AllowBlankValidator: caches @value and @exception_message; uses hash_like? and scrub
• CoerceValidator: resolves type and builds converter; caches @exception_message; inlines valid_type? check; removes type, converter, valid_type?
• DefaultValidator: pre-builds @default_call lambda; removes validate_param!, inlines into validate!
• ExceptValuesValidator: validates proc arity; pre-builds @excepts_call lambda; caches @exception_message
• LengthValidator: validates arguments; stores a Hash message ({ key: :length, min:, max: }) for deferred i18n translation with interpolation
• ValuesValidator: validates proc arity; pre-builds @values_call lambda; caches @exception_message
• RegexpValidator: caches @value and @exception_message; uses Base#scrub
• SameAsValidator: caches @value; stores a Hash message ({ key: :same_as, parameter: }) for deferred i18n translation with interpolation
• PresenceValidator: caches @exception_message
• AllOrNoneOfValidator, MutuallyExclusiveValidator: cache @exception_message
• AtLeastOneOfValidator: caches @exception_message; inverts guard to return if keys_in_common(params).any?
• ExactlyOneOfValidator: caches @exactly_one_exception_message and @mutual_exclusion_exception_message
• ContractScopeValidator: no longer inherits from Base; standalone class with (schema:) constructor and its own fail_fast?

params: argument simplification

• Grape::Exceptions::Validation.new(params: [@scope.full_name(attr_name)]) simplified to params: @scope.full_name(attr_name) throughout, since Validation now coerces to array internally
• attr_accessor :params, :message_key changed to attr_reader

Specs

• Replaced shared let_it_be(:app) with per-describe let(:app) blocks so each test group defines only the route(s) it needs
• Removed endpoint_run_validators.grape notification expectations for empty-validator cases
• Added i18n tests for LengthValidator and SameAsValidator confirming request-time locale is used regardless of definition-time locale
• Added zh-CN translations for length and same_as messages

Removed test-prof dependency

• Removed test-prof gem from Gemfile
• Deleted spec/config/spec_test_prof.rb
• Removed config from the spec helper directory loader

Test plan

• Run full test suite (bundle exec rspec)
• Verify no regressions in validation behavior
• Benchmark request throughput to confirm reduced per-request allocations

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[ericproulx]

Missing UPGRADING notes. Working on it

[dblock]

Is there a tradeoff with things like @exception_message = message(:all_or_none) being always allocated? can they become class variables?

[ericproulx]

Is there a tradeoff with things like @exception_message = message(:all_or_none) being always allocated? can they become class variables?
message involves @option so it can't be a class variable.