Fixes boolean declaration in an external helper file.

CHANGELOG.md

@@ -9,6 +9,7 @@
 
 #### Fixes
 
+* [#1153](https://github.com/ruby-grape/grape/pull/1153): Fixes boolean declaration in an external file - [@towanda](https://github.com/towanda).
 * [#1142](https://github.com/ruby-grape/grape/pull/1142): Makes #declared unavailable to before filters - [@jrforrest](https://github.com/jrforrest).
 * [#1114](https://github.com/ruby-grape/grape/pull/1114): Fix regression which broke identical endpoints with different versions - [@suan](https://github.com/suan).
 * [#1109](https://github.com/ruby-grape/grape/pull/1109): Memoize Virtus attribute and fix memory leak - [@marshall-lee](https://github.com/marshall-lee).

lib/grape/dsl/helpers.rb

@@ -29,6 +29,7 @@ module ClassMethods
         def helpers(new_mod = nil, &block)
           if block_given? || new_mod
             mod = new_mod || Module.new
+            define_boolean_in_mod(mod)
             if new_mod
               inject_api_helpers_to_mod(new_mod) if new_mod.is_a?(BaseHelper)
             end
@@ -51,6 +52,11 @@ def helpers(new_mod = nil, &block)
 
         protected
 
+        def define_boolean_in_mod(mod)
+          return if defined? mod::Boolean
+          mod.const_set('Boolean', Virtus::Attribute::Boolean)
+        end
+
         def inject_api_helpers_to_mod(mod, &_block)
           mod.extend(BaseHelper)
           yield if block_given?

spec/grape/dsl/helpers_spec.rb

@@ -11,6 +11,15 @@ def self.mod
         end
       end
     end
+
+    module BooleanParam
+      extend Grape::API::Helpers
+
+      params :requires_toggle_prm do
+        requires :toggle_prm, type: Boolean
+      end
+    end
+
     describe Helpers do
       subject { Class.new(HelpersSpec::Dummy) }
       let(:proc) do
@@ -39,6 +48,13 @@ def test
 
           expect(subject.mod).to eq mod
         end
+
+        context 'with an external file' do
+          it 'sets Boolean as a Virtus::Attribute::Boolean' do
+            subject.helpers BooleanParam
+            expect(subject.mod::Boolean).to eq Virtus::Attribute::Boolean
+          end
+        end
       end
     end
   end