Demonstrate header handling.

README.md

@@ -17,6 +17,7 @@ A [Grape](http://github.com/ruby-grape/grape) API mounted on Rack.
 * [content_type](api/content_type.rb): an example that overrides the default `Content-Type` or returns data in both JSON and XML formats
 * [upload_file](api/upload_file.rb): an example that demonstrates a file upload and download
 * [entites](api/entities.rb): an example of using [grape-entity](https://github.com/ruby-grape/grape-entity)
+* [headers](api/headers.rb): demonstrates header case-sensitive handling
 
 See
 ---

api/headers.rb

@@ -0,0 +1,21 @@
+module Acme
+  class Headers < Grape::API
+    format :json
+
+    namespace :headers do
+      desc 'Returns a header value.'
+      params do
+        requires :key, type: String
+      end
+      get ':key' do
+        key = params[:key]
+        { key => headers[key] }
+      end
+
+      desc 'Returns all headers.'
+      get do
+        headers
+      end
+    end
+  end
+end

app/api.rb

@@ -13,6 +13,7 @@ class API < Grape::API
     mount ::Acme::ContentType
     mount ::Acme::UploadFile
     mount ::Acme::Entities::API
+    mount ::Acme::Headers
     add_swagger_documentation api_version: 'v1'
   end
 end

spec/api/headers_spec.rb

@@ -0,0 +1,44 @@
+require 'spec_helper'
+
+describe Acme::API do
+  include Rack::Test::Methods
+
+  def app
+    Acme::API
+  end
+
+  it 'returns all headers' do
+    get '/api/headers'
+    expect(JSON.parse(last_response.body)).to eq(
+      'Cookie' => '',
+      'Host' => 'example.org'
+    )
+  end
+
+  it 'returns a Host header' do
+    get '/api/headers/Host'
+    expect(JSON.parse(last_response.body)).to eq('Host' => 'example.org')
+  end
+
+  it 'headers are converted to pascal-case' do
+    get '/api/headers/Host'
+    expect(JSON.parse(last_response.body)).to eq('Host' => 'example.org')
+  end
+
+  it 'headers via Rack::Test API' do
+    header 'Reticulated-Spline', 42
+    get '/api/headers/Reticulated-Spline'
+    expect(JSON.parse(last_response.body)).to eq('Reticulated-Spline' => 42)
+  end
+
+  it 'headers via arg' do
+    get '/api/headers', nil,
+        'HTTP_RETICULATED_SPLINE' => 42,
+        'SOMETHING_ELSE' => 1
+    expect(JSON.parse(last_response.body)).to eq(
+      'Cookie' => '',
+      'Host' => 'example.org',
+      'Reticulated-Spline' => 42
+    )
+  end
+end