Added file, explicitly set file-like response object.

Author: dblock

CHANGELOG.md

@@ -11,6 +11,7 @@
 * [#952](https://github.com/intridea/grape/pull/952): Status method now raises error when called with invalid status code - [@dabrorius](https://github.com/dabrorius).
 * [#957](https://github.com/intridea/grape/pull/957): Regexp validator now supports `allow_blank`, `nil` value behavior changed - [@calfzhou](https://giihub.com/calfzhou).
 * [#962](https://github.com/intridea/grape/pull/962): The `default` attribute with `false` value is documented now - [@ajvondrak](https://github.com/ajvondrak).
+* [#](https://github.com/intridea/grape/pull/): Added `file` method, explicitly setting a file-like response object - [@dblock](https://github.com/dblock).
 
 #### Fixes
 

README.md

@@ -2009,7 +2009,7 @@ class API < Grape::API
 end
 ```
 
-You can also set the response body explicitly with `body`.
+You can set the response body explicitly with `body`.
 
 ```ruby
 class API < Grape::API
@@ -2023,6 +2023,28 @@ end
 
 Use `body false` to return `204 No Content` without any data or content-type.
 
+You can also set the response to a file-like object with `file`.
+
+```ruby
+class FileStreamer
+  def initialize(file_path)
+    @file_path = file_path
+  end
+
+  def each(&blk)
+    File.open(@file_path, 'rb') do |file|
+      file.each(10, &blk)
+    end
+  end
+end
+
+class API < Grape::API
+  get '/' do
+    file FileStreamer.new('file.bin')
+  end
+end
+```
+
 ## Authentication
 
 ### Basic and Digest Auth

lib/grape/dsl/inside_route.rb

@@ -169,6 +169,22 @@ def body(value = nil)
         end
       end
 
+      # Allows you to define the response as a file-like object.
+      #
+      # @example
+      #   get '/file' do
+      #     file FileStreamer.new(...)
+      #   end
+      #
+      #   GET /file # => "contents of file"
+      def file(value = nil)
+        if value
+          @file = value
+        else
+          @file
+        end
+      end
+
       # Allows you to make use of Grape Entities by setting
       # the response body to the serializable hash of the
       # entity provided in the `:with` option. This has the

lib/grape/endpoint.rb

@@ -248,11 +248,13 @@ def run(env)
 
       run_filters after_validations
 
-      response_text = @block ? @block.call(self) : nil
+      response_object = @block ? @block.call(self) : nil
       run_filters afters
       cookies.write(header)
 
-      [status, header, [body || response_text]]
+      # The Body commonly is an Array of Strings, the application instance itself, or a File-like object.
+      response_object = file || [body || response_object]
+      [status, header, response_object]
     end
 
     def build_middleware

lib/grape/middleware/formatter.rb

@@ -29,9 +29,9 @@ def after
         api_format = mime_types[headers[Grape::Http::Headers::CONTENT_TYPE]] || env['api.format']
         formatter = Grape::Formatter::Base.formatter_for api_format, options
         begin
-          bodymap = bodies.collect do |body|
+          bodymap = bodies.respond_to?(:collect) ? bodies.collect do |body|
             formatter.call body, env
-          end
+          end : bodies
         rescue Grape::Exceptions::InvalidFormatter => e
           throw :error, status: 500, message: e.message
         end

spec/grape/endpoint_spec.rb

@@ -927,4 +927,18 @@ def memoized
       expect(last_response.status).to eq(406)
     end
   end
+
+  context 'binary' do
+    before do
+      subject.get do
+        file FileStreamer.new(__FILE__)
+      end
+    end
+
+    it 'suports stream objects in response' do
+      get '/'
+      expect(last_response.status).to eq 200
+      expect(last_response.body).to eq File.read(__FILE__)
+    end
+  end
 end

spec/support/file_streamer.rb

@@ -0,0 +1,11 @@
+class FileStreamer
+  def initialize(file_path)
+    @file_path = file_path
+  end
+
+  def each(&blk)
+    File.open(@file_path, 'rb') do |file|
+      file.each(10, &blk)
+    end
+  end
+end