Fix error message indices

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 * [#2459](https://github.com/ruby-grape/grape/pull/2459): Autocorrect cops - [@ericproulx](https://github.com/ericproulx).
 * [#3458](https://github.com/ruby-grape/grape/pull/2458): Remove unused Grape::Util::Accept::Header - [@ericproulx](https://github.com/ericproulx).
+* [#2463](https://github.com/ruby-grape/grape/pull/2463): Fix error message indices - [@ericproulx](https://github.com/ericproulx).
 * Your contribution here.
 
 ### 2.1.1 (2024-06-22)

lib/grape/validations/attributes_iterator.rb

@@ -21,6 +21,7 @@ def each(&block)
       private
 
       def do_each(params_to_process, parent_indicies = [], &block)
+        @scope.reset_index # gets updated depending on the size of params_to_process
         params_to_process.each_with_index do |resource_params, index|
           # when we get arrays of arrays it means that target element located inside array
           # we need this because we want to know parent arrays indicies

lib/grape/validations/params_scope.rb

@@ -93,17 +93,14 @@ def should_validate?(parameters)
 
       def meets_dependency?(params, request_params)
         return true unless @dependent_on
-
         return false if @parent.present? && !@parent.meets_dependency?(@parent.params(request_params), request_params)
-
         return params.any? { |param| meets_dependency?(param, request_params) } if params.is_a?(Array)
 
         meets_hash_dependency?(params)
       end
 
       def attr_meets_dependency?(params)
         return true unless @dependent_on
-
         return false if @parent.present? && !@parent.attr_meets_dependency?(params)
 
         meets_hash_dependency?(params)
@@ -169,6 +166,10 @@ def required?
         !@optional
       end
 
+      def reset_index
+        @index = nil
+      end
+
       protected
 
       # Adds a parameter declaration to our list of validations.
@@ -297,12 +298,7 @@ def new_lateral_scope(options, &block)
       #   `optional` invocation that opened this scope.
       # @yield parameter scope
       def new_group_scope(attrs, &block)
-        self.class.new(
-          api: @api,
-          parent: self,
-          group: attrs.first,
-          &block
-        )
+        self.class.new(api: @api, parent: self, group: attrs.first, &block)
       end
 
       # Pushes declared params to parent or settings

spec/grape/validations_spec.rb

@@ -1966,6 +1966,48 @@ def validate_param!(attr_name, params)
         expect(last_response.status).to eq(400)
       end
     end
+
+    # Ensure there is no leakage of indices between requests
+    context 'required with a hash inside an array' do
+      before do
+        subject.params do
+          requires :items, type: Array do
+            requires :item, type: Hash do
+              requires :name, type: String
+            end
+          end
+        end
+        subject.post '/required' do
+          'required works'
+        end
+      end
+
+      let(:valid_item) { { item: { name: 'foo' } } }
+
+      let(:params) do
+        {
+          items: [
+            valid_item,
+            valid_item,
+            {}
+          ]
+        }
+      end
+
+      it 'makes sure the error message is independent of the previous request' do
+        post_with_json '/required', {}
+        expect(last_response).to be_bad_request
+        expect(last_response.body).to eq('items is missing, items[item][name] is missing')
+
+        post_with_json '/required', params
+        expect(last_response).to be_bad_request
+        expect(last_response.body).to eq('items[2][item] is missing, items[2][item][name] is missing')
+
+        post_with_json '/required', {}
+        expect(last_response).to be_bad_request
+        expect(last_response.body).to eq('items is missing, items[item][name] is missing')
+      end
+    end
   end
 
   describe 'require_validator' do