add Mongoid support

Gemfile

@@ -15,6 +15,7 @@ gem 'dm-core'
 gem 'dm-aggregates'
 gem 'dm-migrations'
 gem 'dm-sqlite-adapter'
+gem 'mongoid'
 
 group :mysql do
   gem 'mysql', '~> 2.8.1'

Gemfile.lock

@@ -25,6 +25,7 @@ GEM
     addressable (2.2.6)
     archive-tar-minitar (0.5.2)
     arel (3.0.2)
+    bson (1.6.4)
     builder (3.0.4)
     columnize (0.3.5)
     data_objects (0.10.7)
@@ -53,6 +54,12 @@ GEM
     linecache19 (0.5.12)
       ruby_core_source (>= 0.1.4)
     mocha (0.9.12)
+    mongo (1.6.2)
+      bson (~> 1.6.2)
+    mongoid (2.4.11)
+      activemodel (~> 3.1)
+      mongo (<= 1.6.2)
+      tzinfo (~> 0.3.22)
     multi_json (1.5.0)
     mysql (2.8.1)
     mysql2 (0.3.11)
@@ -111,6 +118,7 @@ DEPENDENCIES
   dm-migrations
   dm-sqlite-adapter
   mocha (~> 0.9.8)
+  mongoid
   mysql (~> 2.8.1)
   mysql2 (>= 0.3.6)
   pg (~> 0.11)

lib/will_paginate/mongoid.rb

@@ -0,0 +1,46 @@
+require 'mongoid'
+require 'will_paginate/collection'
+
+module WillPaginate
+  module Mongoid
+    module CriteriaMethods
+      def paginate(options = {})
+        extend CollectionMethods
+        @current_page = WillPaginate::PageNumber(options[:page] || @current_page || 1)
+        @page_multiplier = current_page - 1
+        pp = (options[:per_page] || per_page || WillPaginate.per_page).to_i
+        limit(pp).skip(@page_multiplier * pp)
+      end
+
+      def per_page(value = :non_given)
+        if value == :non_given
+          options[:limit] == 0 ? nil : options[:limit] # in new Mongoid versions a nil limit is saved as 0
+        else
+          limit(value)
+        end
+      end
+
+      def page(page)
+        paginate(:page => page)
+      end
+    end
+
+    module CollectionMethods
+      attr_reader :current_page
+
+      def total_entries
+        @total_entries ||= count
+      end
+
+      def total_pages
+        (total_entries / per_page.to_f).ceil
+      end
+
+      def offset
+        @page_multiplier * per_page
+      end
+    end
+
+    ::Mongoid::Criteria.send(:include, CriteriaMethods)
+  end
+end

spec/finders/mongoid_spec.rb

@@ -0,0 +1,132 @@
+require 'spec_helper'
+require 'will_paginate/mongoid'
+
+Mongoid.database = Mongo::Connection.new.db('will_paginate_test')
+
+class MongoidModel
+  include Mongoid::Document
+end
+
+describe WillPaginate::Mongoid do
+  before(:all) do
+    MongoidModel.delete_all
+    4.times { MongoidModel.create! }
+  end
+
+  let(:criteria) { MongoidModel.criteria }
+
+  describe "#page" do
+    it "should forward to the paginate method" do
+      criteria.expects(:paginate).with(:page => 2).returns("itself")
+      criteria.page(2).should == "itself"
+    end
+
+    it "should not override per_page if set earlier in the chain" do
+      criteria.paginate(:per_page => 10).page(1).per_page.should == 10
+      criteria.paginate(:per_page => 20).page(1).per_page.should == 20
+    end
+  end
+
+  describe "#per_page" do
+    it "should set the limit if given an argument" do
+      criteria.per_page(10).options[:limit].should == 10
+    end
+
+    it "should return the current limit if no argument is given" do
+      criteria.per_page.should == nil
+      criteria.per_page(10).per_page.should == 10
+    end
+
+    it "should be interchangable with limit" do
+      criteria.limit(15).per_page.should == 15
+    end
+
+    it "should be nil'able" do
+      criteria.per_page(nil).per_page.should be_nil
+    end
+  end
+
+  describe "#paginate" do
+    it "should use criteria" do
+      criteria.paginate.should be_instance_of(::Mongoid::Criteria)
+    end
+
+    it "should not override page number if set earlier in the chain" do
+      criteria.page(3).paginate.current_page.should == 3
+    end
+
+    it "should limit according to per_page parameter" do
+      criteria.paginate(:per_page => 10).options.should include(:limit => 10)
+    end
+
+    it "should skip according to page and per_page parameters" do
+      criteria.paginate(:page => 2, :per_page => 5).options.should include(:skip => 5)
+    end
+
+    specify "first fallback value for per_page option is the current limit" do
+      criteria.limit(12).paginate.options.should include(:limit => 12)
+    end
+
+    specify "second fallback value for per_page option is WillPaginate.per_page" do
+      criteria.paginate.options.should include(:limit => WillPaginate.per_page)
+    end
+
+    specify "page should default to 1" do
+      criteria.paginate.options.should include(:skip => 0)
+    end
+
+    it "should convert strings to integers" do
+      criteria.paginate(:page => "2", :per_page => "3").options.should include(:limit => 3, :limit => 3)
+    end
+
+    describe "collection compatibility" do
+      describe "#total_count" do
+        it "should be calculated correctly" do
+          criteria.paginate(:per_page => 1).total_entries.should == 4
+          criteria.paginate(:per_page => 3).total_entries.should == 4
+        end
+
+        it "should be cached" do
+          criteria.expects(:count).once.returns(123)
+          criteria.paginate
+          2.times { criteria.total_entries.should == 123 }
+        end
+      end
+
+      it "should calculate total_pages" do
+        criteria.paginate(:per_page => 1).total_pages.should == 4
+        criteria.paginate(:per_page => 3).total_pages.should == 2
+        criteria.paginate(:per_page => 10).total_pages.should == 1
+      end
+
+      it "should return per_page" do
+        criteria.paginate(:per_page => 1).per_page.should == 1
+        criteria.paginate(:per_page => 5).per_page.should == 5
+      end
+
+      describe "#current_page" do
+        it "should return current_page" do
+          criteria.paginate(:page => 1).current_page.should == 1
+          criteria.paginate(:page => 3).current_page.should == 3
+        end
+
+        it "should be casted to PageNumber" do
+          criteria.paginate(:page => 1).current_page.should be_instance_of(WillPaginate::PageNumber)
+        end
+      end
+
+      it "should return offset" do
+        criteria.paginate(:page => 1).offset.should == 0
+        criteria.paginate(:page => 2, :per_page => 5).offset.should == 5
+        criteria.paginate(:page => 3, :per_page => 10).offset.should == 20
+      end
+
+      it "should not pollute plain mongoid criterias" do
+        %w(total_entries total_pages current_page).each do |method|
+          criteria.should_not respond_to(method)
+        end
+        criteria.offset.should be_nil # this is already a criteria method
+      end
+    end
+  end
+end