Allow param type definition in route_param

CHANGELOG.md

@@ -9,6 +9,7 @@
 * [#1238](https://github.com/ruby-grape/grape/pull/1238): Call `after` of middleware on error - [@namusyaka](https://github.com/namusyaka).
 * [#1243](https://github.com/ruby-grape/grape/pull/1243): Add `header` support for middleware - [@namusyaka](https://github.com/namusyaka).
 * [#1252](https://github.com/ruby-grape/grape/pull/1252): Allow default to be a subset or equal to allowed values without raising IncompatibleOptionValues - [@jeradphelps](https://github.com/jeradphelps).
+* [#1255](https://github.com/ruby-grape/grape/pull/1255): Allow param type definition in route_param - [@namusyaka](https://github.com/namusyaka)
 * Your contribution here.
 
 #### Fixes

README.md

@@ -1148,6 +1148,19 @@ namespace :statuses do
 end
 ```
 
+You can also define a route parameter type by passing to `route_param`'s options.
+
+```ruby
+namespace :arithmetic do
+  route_param :n, type: Integer do
+    desc 'Returns in power'
+    get 'power' do
+      params[:n] ** params[:n]
+    end
+  end
+end
+```
+
 ### Custom Validators
 
 ```ruby

lib/grape/dsl/routing.rb

@@ -185,7 +185,13 @@ def reset_routes!
         # @option options [Regexp] You may supply a regular expression that the declared parameter must meet.
         def route_param(param, options = {}, &block)
           options = options.dup
-          options[:requirements] = { param.to_sym => options[:requirements] } if options[:requirements].is_a?(Regexp)
+          options[:requirements] = {
+            param.to_sym => options[:requirements]
+          } if options[:requirements].is_a?(Regexp)
+
+          Grape::Validations::ParamsScope.new(api: self) do
+            requires param, type: options[:type]
+          end if options.key?(:type)
           namespace(":#{param}", options, &block)
         end
 

spec/grape/api_spec.rb

@@ -249,6 +249,18 @@ def app
       get '/users/23'
       expect(last_response.status).to eq(200)
     end
+
+    context 'with param type definitions' do
+      it 'is used by passing to options' do
+        subject.namespace :route_param do
+          route_param :foo, type: Integer do
+            get { params.to_json }
+          end
+        end
+        get '/route_param/1234'
+        expect(last_response.body).to eq("{\"foo\":1234}")
+      end
+    end
   end
 
   describe '.route' do