Document the min/max Items/Length fields if the attribute uses the le…

…ngth validator.

lib/grape-swagger/doc_methods/parse_params.rb

@@ -25,6 +25,7 @@ def call(param, settings, path, route, definitions, consumes) # rubocop:disable
           document_default_value(settings) unless value_type[:is_array]
           document_range_values(settings) unless value_type[:is_array]
           document_required(settings)
+          document_length_limits(value_type)
           document_additional_properties(definitions, settings) unless value_type[:is_array]
           document_add_extensions(settings)
           document_example(settings)
@@ -163,6 +164,16 @@ def param_type(value_type, consumes)
           end
         end
 
+        def document_length_limits(value_type)
+          if value_type[:is_array]
+            @parsed_param[:minItems] = value_type[:min_length] if value_type.key?(:min_length)
+            @parsed_param[:maxItems] = value_type[:max_length] if value_type.key?(:max_length)
+          else
+            @parsed_param[:minLength] = value_type[:min_length] if value_type.key?(:min_length)
+            @parsed_param[:maxLength] = value_type[:max_length] if value_type.key?(:max_length)
+          end
+        end
+
         def parse_enum_or_range_values(values)
           case values
           when Proc

spec/swagger_v2/param_type_spec.rb

@@ -27,9 +27,51 @@ def app
         { message: 'hi' }
       end
 
+      if Gem::Version.new(Grape::VERSION) >= Gem::Version.new('2.1.0')
+        desc 'other_action' do
+          consumes ['application/x-www-form-urlencoded']
+        end
+        params do
+          requires :input, type: String, length: { min: 1, max: 12 }
+          requires :arr, type: [Integer], length: { min: 1, max: 12 }
+        end
+        post :other_action do
+          { message: 'hi' }
+        end
+      end
+
       add_swagger_documentation
     end
   end
+
+  context 'when length validator is used', if: Gem::Version.new(Grape::VERSION) >= Gem::Version.new('2.1.0') do
+    subject do
+      get '/swagger_doc/other_action'
+    end
+
+    it 'documents the length/item limits correctly' do
+      subject
+
+      expect(last_response.status).to eq 200
+      expect(JSON.parse(last_response.body)['paths']['/other_action']['post']['parameters']).to eq([{
+        'in' => 'formData',
+        'maxLength' => 12,
+        'minLength' => 1,
+        'name' => 'input',
+        'required' => true,
+        'type' => 'string'
+      }, {
+        'in' => 'formData',
+        'items' => { 'format' => 'int32', 'type' => 'integer' },
+        'maxItems' => 12,
+        'minItems' => 1,
+        'name' => 'arr',
+        'required' => true,
+        'type' => 'array'
+      }])
+    end
+  end
+
   context 'with no documentation hash' do
     subject do
       get '/swagger_doc/action'