Add support for Grape

Signed-off-by: David Celis <[email protected]>

Author: davidcelis

api-pagination.gemspec

@@ -16,6 +16,7 @@ Gem::Specification.new do |s|
   s.test_files    = Dir['spec/**/*']
   s.require_paths = ['lib']
 
-  s.add_development_dependency 'actionpack'
   s.add_development_dependency 'rspec'
+  s.add_development_dependency 'grape'
+  s.add_development_dependency 'actionpack'
 end

lib/api-pagination/hooks.rb

@@ -13,6 +13,12 @@ def self.init
         ActionController::API.send(:include, Rails::Pagination)
       end
 
+      begin; require 'grape'; rescue LoadError; end
+      if defined?(Grape::API)
+        require 'grape/pagination'
+        Grape::API.send(:include, Grape::Pagination)
+      end
+
       begin; require 'will_paginate'; rescue LoadError; end
       if defined?(WillPaginate::CollectionMethod)
         WillPaginate::CollectionMethods.module_eval do

lib/grape/pagination.rb

@@ -0,0 +1,46 @@
+module Grape
+  module Pagination
+    def self.included(base)
+      Grape::Endpoint.class_eval do
+        def paginate(collection)
+          collection.page(params[:page]).per(params[:per_page]).tap do |scope|
+            links = (header['Link'] || "").split(',').map(&:strip)
+
+            url   = request.url.sub(/\?.*$/, '')
+            pages = {}
+
+            unless scope.first_page?
+              pages[:first] = 1
+              pages[:prev]  = scope.current_page - 1
+            end
+
+            unless scope.last_page?
+              pages[:last] = scope.total_pages
+              pages[:next] = scope.current_page + 1
+            end
+
+            pages.each do |k, v|
+              old_params = Rack::Utils.parse_query(request.query_string)
+              new_params = old_params.merge('page' => v)
+              links << %(<#{url}?#{new_params.to_param}>; rel="#{k}")
+            end
+
+            header 'Link', links.join(', ') unless links.empty?
+          end
+        end
+      end
+
+      base.class_eval do
+        def self.paginate(options = {})
+          options.reverse_merge!(per_page: 10)
+          params do
+            optional :page,     type: Integer, default: 1,
+                                desc: 'Page offset to fetch.'
+            optional :per_page, type: Integer, default: options[:per_page],
+                                desc: 'Number of results to return per page.'
+          end
+        end
+      end
+    end
+  end
+end

spec/grape_spec.rb

@@ -0,0 +1,83 @@
+require 'spec_helper'
+
+describe NumbersAPI do
+  describe 'GET #index' do
+    context 'without enough items to give more than one page' do
+      it 'should not paginate' do
+        get :numbers, count: 20
+        expect(last_response.headers.keys).not_to include('Link')
+      end
+    end
+
+    context 'with existing Link headers' do
+      before { get :numbers, count: 30, with_headers: true }
+      let(:links) { last_response.headers['Link'].split(', ') }
+
+      it 'should keep existing Links' do
+        expect(links).to include('<http://example.org/numbers?count=30>; rel="without"')
+      end
+
+      it 'should contain pagination Links' do
+        expect(links).to include('<http://example.org/numbers?count=30&page=2&with_headers=true>; rel="next"')
+        expect(links).to include('<http://example.org/numbers?count=30&page=2&with_headers=true>; rel="last"')
+      end
+    end
+
+    context 'with enough items to paginate' do
+      context 'when on the first page' do
+        before { get :numbers, :count => 100 }
+        let(:links) { last_response.headers['Link'].split(', ') }
+
+        it 'should not give a link with rel "first"' do
+          expect(links).not_to include('rel="first"')
+        end
+
+        it 'should not give a link with rel "prev"' do
+          expect(links).not_to include('rel="prev"')
+        end
+
+        it 'should give a link with rel "last"' do
+          expect(links).to include('<http://example.org/numbers?count=100&page=4>; rel="last"')
+        end
+
+        it 'should give a link with rel "next"' do
+          expect(links).to include('<http://example.org/numbers?count=100&page=2>; rel="next"')
+        end
+      end
+
+      context 'when on the last page' do
+        before { get :numbers, :count => 100, :page => 4 }
+        let(:links) { last_response.headers['Link'].split(', ') }
+
+        it 'should not give a link with rel "last"' do
+          expect(links).not_to include('rel="last"')
+        end
+
+        it 'should not give a link with rel "next"' do
+          expect(links).not_to include('rel="next"')
+        end
+
+        it 'should give a link with rel "first"' do
+          expect(links).to include('<http://example.org/numbers?count=100&page=1>; rel="first"')
+        end
+
+        it 'should give a link with rel "prev"' do
+          expect(links).to include('<http://example.org/numbers?count=100&page=3>; rel="prev"')
+        end
+      end
+
+      context 'when somewhere comfortably in the middle' do
+        it 'should give all pagination links' do
+          get :numbers, count: 100, page: 2
+
+          links = last_response.headers['Link'].split(', ')
+
+          expect(links).to include('<http://example.org/numbers?count=100&page=1>; rel="first"')
+          expect(links).to include('<http://example.org/numbers?count=100&page=4>; rel="last"')
+          expect(links).to include('<http://example.org/numbers?count=100&page=3>; rel="next"')
+          expect(links).to include('<http://example.org/numbers?count=100&page=1>; rel="prev"')
+        end
+      end
+    end
+  end
+end

spec/rails_spec.rb

@@ -1,4 +1,4 @@
-require 'rails_spec_helper'
+require 'spec_helper'
 
 describe NumbersController, :type => :controller do
   describe 'GET #index' do
@@ -10,8 +10,9 @@
     end
 
     context 'with existing Link headers' do
-      before(:each) do
+      before do
         get :index, count: 30, with_headers: true
+
         @links = response.headers['Link'].split(', ')
       end
 
@@ -27,7 +28,7 @@
 
     context 'with enough items to paginate' do
       context 'when on the first page' do
-        before(:each) do
+        before do
           get :index, count: 100
 
           @links = response.headers['Link'].split(', ')
@@ -51,7 +52,7 @@
       end
 
       context 'when on the last page' do
-        before(:each) do
+        before do
           get :index, count: 100, page: 4
 
           @links = response.headers['Link'].split(', ')

spec/spec_helper.rb

@@ -1,20 +1,32 @@
-require 'api-pagination'
 require 'rspec/autorun'
-require 'ostruct'
+require 'support/numbers_controller'
+require 'api-pagination'
+require 'support/numbers_api'
 
 # Quacks like Kaminari
-PaginatedSet = Struct.new(:current_page, :total_count) do
-  def limit_value() 25 end
-
+PaginatedSet = Struct.new(:current_page, :per_page, :total_count) do
   def total_pages
-    total_count.zero? ? 1 : (total_count.to_f / limit_value).ceil
+    total_count.zero? ? 1 : (total_count.to_f / per_page).ceil
   end
 
   def first_page?() current_page == 1 end
   def last_page?() current_page == total_pages end
+
+  def page(page)
+    current_page = page
+    self
+  end
+
+  def per(per)
+    per_page = per
+    self
+  end
 end
 
 RSpec.configure do |config|
+  config.include Rack::Test::Methods
+  config.include ControllerExampleGroup, :type => :controller
+
   # Disable the 'should' syntax.
   config.expect_with :rspec do |c|
     c.syntax = :expect
@@ -25,4 +37,8 @@ def last_page?() current_page == total_pages end
   # the seed, which is printed after each run.
   #     --seed 1234
   config.order = 'random'
+
+  def app
+    NumbersAPI
+  end
 end

spec/support/numbers_api.rb

@@ -0,0 +1,20 @@
+class NumbersAPI < Grape::API
+  format :json
+
+  desc 'Return some paginated set of numbers'
+  paginate :per_page => 25
+  params do
+    requires :count, :type => Integer
+    optional :with_headers, :default => false, :type => Boolean
+  end
+  get :numbers do
+    if params[:with_headers]
+      url   = request.url.sub(/\?.*/, '')
+      query = Rack::Utils.parse_query(request.query_string)
+      query.delete('with_headers')
+      header 'Link', %(<#{url}?#{query.to_query}>; rel="without")
+    end
+
+    paginate PaginatedSet.new(params[:page], params[:per_page], params[:count])
+  end
+end

spec/rails_spec_helper.rb renamed to spec/support/numbers_controller.rb

@@ -1,5 +1,5 @@
 require 'action_controller'
-require 'spec_helper'
+require 'ostruct'
 
 module Rails
   def self.application
@@ -57,11 +57,7 @@ def index
       headers['Link'] = %(<#{numbers_url}?#{query.to_param}>; rel="without") if params[:with_headers]
     end
 
-    @numbers = PaginatedSet.new(page, total)
+    @numbers = PaginatedSet.new(page, 25, total)
     render json: @numbers
   end
 end
-
-RSpec.configure do |config|
-  config.include ControllerExampleGroup, :type => :controller
-end