Validate the params of an optional Hash scope without the iterator

CHANGELOG.md

@@ -36,6 +36,7 @@
 * [#3071](https://github.com/ruby-grape/grape/pull/3071): Skip the query parse when building the params of a request with no query string - [@ericproulx](https://github.com/ericproulx).
 * [#3072](https://github.com/ruby-grape/grape/pull/3072): Answer the `Accept` lists axios, jQuery and HTTPie send without negotiating them on every request - [@ericproulx](https://github.com/ericproulx).
 * [#3073](https://github.com/ruby-grape/grape/pull/3073): Let a `rescue_from :all` in a namespace or mounted API outrank the enclosing scope's handlers - [@ericproulx](https://github.com/ericproulx).
+* [#3075](https://github.com/ruby-grape/grape/pull/3075): Validate the params of an optional Hash scope without the attributes iterator - [@ericproulx](https://github.com/ericproulx).
 * [#3076](https://github.com/ruby-grape/grape/pull/3076): Skip the query merge when building the params of a body sent without a query string - [@ericproulx](https://github.com/ericproulx).
 * Your contribution here.
 

lib/grape/validations/validators/base.rb

@@ -121,17 +121,19 @@ def validate_param!(attr_name, params)
         # time a validator is built. See #validate and #validate!.
         def choose_validation_path(scope)
           @always_validated = scope.always_validated?
-          @direct = @always_validated && !scope.iterates_elements?
+          @direct = scope.independent? && scope.array_depth.zero?
           @direct_elements = scope.validated_when_given? && scope.iterates_elements? && scope.array_depth == 1
         end
 
-        # #validate! on a scope that always validates and does not iterate
-        # elements, once its params resolved to a Hash: the root scope and the
-        # required Hash scopes under it, which is most validators of most
-        # endpoints. There the iterator hands back that Hash alone, and every
-        # scope on the chain is required with no dependency, so the checks
-        # around the attribute loop drop out. The machinery cost more than
-        # the validation itself.
+        # #validate! on a scope with no Array scope and no +given+ on its
+        # chain, once its params resolved to a Hash: the root scope and the
+        # Hash scopes under it, required or optional, which is most validators
+        # of most endpoints. There the iterator hands back that Hash alone,
+        # and no scope on the chain has a dependency to meet. An optional one
+        # is only passed over when its params are empty, and #validate does
+        # not get this far with those (see ParamsScope#should_validate?). So
+        # the checks around the attribute loop drop out. The machinery cost
+        # more than the validation itself.
         def validate_attributes!(params)
           array_errors = nil
 

lib/grape/validations/validators/default_validator.rb

@@ -31,10 +31,11 @@ def validate!(params)
         private
 
         # Also #validate!'s whole job where Base#validate_attributes! applies:
-        # a scope that is always validated and does not iterate elements, once
-        # its params resolved to a Hash -- the root scope of every +params+
-        # block with a default in it. A scope like that depends on no other
-        # param, so the iterator and its dependency check have nothing to add.
+        # a scope with no Array scope and no +given+ on its chain, once its
+        # params resolved to a Hash -- the root scope of every +params+ block
+        # with a default in it, and the Hash scopes under it. A scope like
+        # that depends on no other param, so the iterator and its dependency
+        # check have nothing to add.
         def apply_defaults(params)
           @attrs.each do |attr_name|
             params[attr_name] = @default_call.call(params) if params[attr_name].nil?