validation for array in params

CHANGELOG.markdown

@@ -1,6 +1,7 @@
 Next Release
 ============
 
+* [#333](https://github.com/intridea/grape/pull/333): Validation for array in params - [@flyerhzm](https://github.com/flyerhzm).
 * [#306](https://github.com/intridea/grape/issues/306): Added I18n support for all Grape exceptions - [@niedhui](https://github.com/niedhui).
 * [#294](https://github.com/intridea/grape/issues/294): Extracted `Grape::Entity` into a [grape-entity](https://github.com/agileanimal/grape-entity) gem - [@agileanimal](https://github.com/agileanimal).
 * [#309](https://github.com/intridea/grape/pull/309): An XML format API will return an error instead of returning a string representation of the response if the latter cannot be converted to XML - [@dblock](http://github.com/dblock).

lib/grape/validations.rb

@@ -21,9 +21,11 @@ def initialize(attrs, options, required, scope)
       def validate!(params)
         params = @scope.params(params)
 
-        @attrs.each do |attr_name|
-          if @required || params.has_key?(attr_name)
-            validate_param!(attr_name, params)
+        (params.is_a?(Array) ? params : [params]).each do |resource_params|
+          @attrs.each do |attr_name|
+            if @required || resource_params.has_key?(attr_name)
+              validate_param!(attr_name, resource_params)
+            end
           end
         end
       end

spec/grape/validations_spec.rb

@@ -58,6 +58,29 @@ def app; subject end
       end
     end
 
+    context 'group' do
+      before do
+        subject.params {
+          group :items do
+            requires :key
+          end
+        }
+        subject.get '/required' do 'required works'; end
+      end
+
+      it 'errors when param not present' do
+        get '/required'
+        last_response.status.should == 400
+        last_response.body.should == 'missing parameter: items[key]'
+      end
+
+      it "doesn't throw a missing param when param is present" do
+        get '/required', { :items => [:key => 'hello', :key => 'world'] }
+        last_response.status.should == 200
+        last_response.body.should == 'required works'
+      end
+    end
+
     context 'custom validation' do
       module CustomValidations
         class Customvalidator < Grape::Validations::Validator
@@ -147,19 +170,19 @@ def validate_param!(attr_name, params)
               end
             end
           end
-          
+
           specify 'the parent namespace uses the validator' do
             get '/nested/one', { :custom => 'im wrong, validate me'}
             last_response.status.should == 400
             last_response.body.should == 'custom: is not custom!'
           end
-          
+
           specify 'the nested namesapce inherits the custom validator' do
             get '/nested/nested/two', { :custom => 'im wrong, validate me'}
             last_response.status.should == 400
             last_response.body.should == 'custom: is not custom!'
           end
-          
+
           specify 'peer namesapces does not have the validator' do
             get '/peer/one', { :custom => 'im not validated' }
             last_response.status.should == 200