Fix parameter validation with an empty optional nested Array. Closes #723.

Author: ipkes

CHANGELOG.md

@@ -11,6 +11,7 @@
 
 * [#1365](https://github.com/ruby-grape/grape/pull/1365): Fix finding exception handler in error middleware - [@ktimothy](https://github.com/ktimothy).
 * [#1380](https://github.com/ruby-grape/grape/pull/1380): Fix `allow_blank: false` for `Time` attributes with valid values causes `NoMethodError` - [@ipkes](https://github.com/ipkes).
+* [#1384](https://github.com/ruby-grape/grape/pull/1384): Fix parameter validation with an empty optional nested `Array` - [@ipkes](https://github.com/ipkes).
 
 0.16.2 (4/12/2016)
 ==================

lib/grape/validations/params_scope.rb

@@ -35,10 +35,13 @@ def initialize(opts, &block)
       # @return [Boolean] whether or not this entire scope needs to be
       #   validated
       def should_validate?(parameters)
-        return false if @optional && params(parameters).respond_to?(:all?) && params(parameters).all?(&:blank?)
+        return false if @optional && (params(parameters).blank? ||
+                                       any_element_blank?(parameters))
+
         @dependent_on.each do |dependency|
           return false if params(parameters).try(:[], dependency).blank?
         end if @dependent_on
+
         return true if parent.nil?
         parent.should_validate?(parameters)
       end
@@ -357,6 +360,10 @@ def extract_message_option(attrs)
       def options_key?(type, key, validations)
         validations[type].respond_to?(:key?) && validations[type].key?(key) && !validations[type][key].nil?
       end
+
+      def any_element_blank?(parameters)
+        params(parameters).respond_to?(:any?) && params(parameters).any?(&:blank?)
+      end
     end
   end
 end

spec/grape/validations/validators/default_spec.rb

@@ -49,6 +49,32 @@ class API < Grape::API
         get '/array' do
           { array: params[:array] }
         end
+
+        params do
+          requires :thing1
+          optional :more_things, type: Array do
+            requires :nested_thing
+            requires :other_thing, default: 1
+          end
+        end
+        get '/optional_array' do
+          { thing1: params[:thing1] }
+        end
+
+        params do
+          requires :root, type: Hash do
+            optional :some_things, type: Array do
+              requires :foo
+              optional :options, type: Array do
+                requires :name, type: String
+                requires :value, type: String
+              end
+            end
+          end
+        end
+        get '/nested_optional_array' do
+          { root: params[:root] }
+        end
       end
     end
   end
@@ -57,6 +83,24 @@ def app
     ValidationsSpec::DefaultValidatorSpec::API
   end
 
+  it 'lets you leave required values nested inside an optional blank' do
+    get '/optional_array', thing1: 'stuff'
+    expect(last_response.status).to eq(200)
+    expect(last_response.body).to eq({ thing1: 'stuff' }.to_json)
+  end
+
+  it 'allows optional arrays to be omitted' do
+    params = { some_things:
+                [{ foo: 'one', options: [{ name: 'wat', value: 'nope' }] },
+                 { foo: 'two' },
+                 { foo: 'three', options: [{ name: 'wooop', value: 'yap' }] }
+                ]
+             }
+    get '/nested_optional_array', root: params
+    expect(last_response.status).to eq(200)
+    expect(last_response.body).to eq({ root: params }.to_json)
+  end
+
   it 'set default value for optional param' do
     get('/')
     expect(last_response.status).to eq(200)