Added support to API proxies.

lib/grape/pagination.rb

@@ -8,10 +8,16 @@ def paginate(collection)
             :per_page => (params[:per_page] || settings[:per_page])
           }
           collection = ApiPagination.paginate(collection, options)
+          links      = (header['Link'] || "").split(',').map(&:strip)
+          pages      = ApiPagination.pages_from(collection)
 
-          links = (header['Link'] || "").split(',').map(&:strip)
-          url   = request.url.sub(/\?.*$/, '')
-          pages = ApiPagination.pages_from(collection)
+          url = request.url.sub(/\?.*$/, '')
+          url = URI.parse(url).request_uri if settings[:relative_uri]
+
+          if settings[:exclude_base_path]
+            base_path_regexp = Regexp.new("^" + settings[:exclude_base_path])
+            url = url.sub(base_path_regexp, "")
+          end
 
           pages.each do |k, v|
             old_params = Rack::Utils.parse_query(request.query_string)
@@ -28,6 +34,25 @@ def paginate(collection)
 
       base.class_eval do
         def self.paginate(options = {})
+          # URIs can also be relative, useful when using API proxies.
+          #
+          # From RFC 5988 (Web Linking):
+          # "If the URI-Reference is relative, parsers MUST resolve it
+          # as per [RFC3986], Section 5.""
+          set :relative_uri, (options[:relative_uri] || false)
+
+          # When using API proxies, you probably want to hide base path
+          # from returned links since proxies point to your API base path
+          # directly making its own resources not have such base path.
+          #
+          # E.g.
+          # If your application has the following API resource:
+          #   mywebsite.example.com/api/v1/resource.json
+          # And that's accessible though the following API proxy resource:
+          #   myproxy.example.com/v1/resource.json
+          # You don't want links to return '/api/v1/...', but '/v1/...'.
+          set :exclude_base_path, (options[:exclude_base_path] || false)
+
           set :per_page, (options[:per_page] || 25)
           params do
             optional :page,     :type => Integer, :default => 1,

spec/grape_spec.rb

@@ -53,3 +53,19 @@
     end
   end
 end
+
+describe NumbersProxiedAPI do
+  describe 'GET #index' do
+    let(:links) { last_response.headers['Link'].split(', ') }
+    let(:total) { last_response.headers['Total'].to_i }
+
+    context 'with existing Link headers' do
+      before { get "/api/numbers", :count => 30 }
+
+      it 'should contain relative pagination Links without base path' do
+        expect(links).to include('</numbers?count=30&page=2>; rel="next"')
+        expect(links).to include('</numbers?count=30&page=3>; rel="last"')
+      end
+    end
+  end
+end

spec/spec_helper.rb

@@ -1,5 +1,6 @@
 require 'support/numbers_controller'
 require 'support/numbers_api'
+require 'support/numbers_proxied_api'
 require 'api-pagination'
 
 if ENV['PAGINATOR']
@@ -31,6 +32,8 @@
   config.order = 'random'
 
   def app
-    NumbersAPI
+    # Allows us to test different API apps.
+    # e.g. NumbersApi, NumbersProxiedApi...
+    described_class
   end
 end

spec/support/numbers_proxied_api.rb

@@ -0,0 +1,22 @@
+require 'grape'
+require 'api-pagination'
+
+class NumbersProxiedAPI < Grape::API
+  format :json
+
+  # This namespace is here simulate that the API is nested in a directory.
+  # When using an API proxy, this base path vanishes since the proxy host
+  # is the new base. That's why we have 'exclude_base_path'.
+  namespace :api do
+    desc 'Return some paginated set of numbers'
+    paginate :per_page          => 10,
+             :exclude_base_path => "/api",
+             :relative_uri      => true
+    params do
+      requires :count, :type => Integer
+    end
+    get :numbers do
+      paginate (1..params[:count]).to_a
+    end
+  end
+end