Custom options for reusable params blocks

CHANGELOG.md

@@ -3,6 +3,7 @@ Next Release
 
 #### Features
 
+* [#639](https://github.com/intridea/grape/pull/639): Adds options for reusable params blocks
 * [#637](https://github.com/intridea/grape/pull/637): Added 'exactly_one_of' validation - [@Morred](https://github.com/Morred).
 * [#626](https://github.com/intridea/grape/pull/626): Mutually exclusive params - [@oliverbarnes](https://github.com/oliverbarnes).
 * [#617](https://github.com/intridea/grape/pull/617): Running tests on Ruby 2.1.1, Rubinius 2.1 and 2.2, Ruby and JRuby HEAD - [@dblock](https://github.com/dblock).

README.md

@@ -719,6 +719,11 @@ module SharedParams
     optional :end_date
   end
 
+  params :order do |options|
+    optional :order_by, type:Symbol, values:options[:order_by], default:options[:default_order_by]
+    optional :order,    type:Symbol, values:%i(asc desc), default:options[:default_order]
+  end
+
   params :pagination do
     optional :page, type: Integer
     optional :per_page, type: Integer
@@ -731,7 +736,9 @@ class API < Grape::API
   desc "Get collection"
   params do
     use :period, :pagination
+    use :order, order_by:%i(id created_at), default_order_by: :created_at, default_order: :asc
   end
+
   get do
     Collection.from(params[:start_date]).to(params[:end_date])
               .page(params[:page]).per(params[:per_page])

lib/grape/validations.rb

@@ -158,11 +158,12 @@ def params(params)
 
       def use(*names)
         named_params = @api.settings[:named_params] || {}
+        options = names.last.is_a?(Hash) ? names.pop : {}
         names.each do |name|
           params_block = named_params.fetch(name) do
             raise "Params :#{name} not found!"
           end
-          instance_eval(&params_block)
+          instance_exec(options, &params_block)
         end
       end
       alias_method :use_scope, :use

spec/grape/validations_spec.rb

@@ -800,18 +800,23 @@ module SharedParams
           subject.helpers SharedParams
 
           subject.helpers do
-            params :pagination do
+            params :pagination do |options|
               optional :page, type: Integer
               optional :per_page, type: Integer
             end
+            params :order do |options|
+              optional :order, type: Symbol, values: [:asc, :desc], default: options[:default_order]
+              optional :order_by, type: Symbol, values: options[:order_by], default: options[:default_order_by]
+            end
           end
         end
 
         it 'by #use' do
           subject.params do
             use :pagination
+            use :order, default_order: :asc, order_by: [:name, :created_at], default_order_by: :created_at
           end
-          expect(subject.settings[:declared_params]).to eq [:page, :per_page]
+          expect(subject.settings[:declared_params]).to eq [:page, :per_page, :order, :order_by]
         end
 
         it 'by #use with multiple params' do