ruby-grape / grape / 25718219098 / 17

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Pull #2702

github

Add oneof: option for polymorphic Hash parameters

Resolves #2385. A Hash parameter can now declare multiple acceptable
shapes:

    params do
      requires :value, type: Hash, oneof: [
        proc { requires :fixed_price, type: Float },
        proc do
          requires :time_unit, type: String
          requires :rate, type: Float
        end
      ]
    end

At request time variants are tried in declaration order against a
deep-dup of the value; the first variant whose validators raise no
exceptions wins, and any coercions it performed are applied to the
parent params.

Each variant block runs in a real `ParamsScope` backed by a small
`OneofCollector` that captures validators locally instead of
registering them on the API. Because variants are evaluated through
the standard scope, the full params DSL is available inside —
`regexp:`, `values:`, `allow_blank:`, nested `Hash`/`Array`, and
so on all work without re-implementation. Variant validators are
themselves real frozen `Validators::Base` instances reused at
request time.

Definition-time guards: `oneof:` requires `type: Hash`, the array
must be non-empty, and every entry must be a `Proc`. Otherwise an
`ArgumentError` is raised at boot.

Adds `Grape::Validations::OneofCollector`,
`Grape::Validations::Validators::OneofValidator`, an `oneof` i18n
key, and `process_oneof!` in `ParamsScope#validates`. README and
CHANGELOG updated.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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