Allow eager loading to work as a default scope. Fixes #1676.

CHANGELOG.md

@@ -71,6 +71,8 @@ For instructions on upgrading to newer versions, visit
 
 ### Resolved Issues
 
+* \#1676 Allow eager loading to work as a default scope.
+
 * \#1665/#1672 Expand complex criteria in nested criteria selectors, like
   #matches. (Hans Hasselberg)
 

lib/mongoid/criteria.rb

@@ -262,6 +262,7 @@ def as_conditions
       scope_options = @options.dup
       sorting = scope_options.delete(:sort)
       scope_options[:order_by] = sorting if sorting
+      scope_options[:includes] = inclusions.map(&:name) if inclusions.any?
       { :where => @selector }.merge(scope_options)
     end
     alias :to_ary :to_a

lib/mongoid/criterion/inclusion.rb

@@ -190,7 +190,7 @@ def in(attributes = {})
       #
       # @since 2.2.0
       def includes(*relations)
-        relations.each do |name|
+        relations.flatten.each do |name|
           inclusions.push(klass.reflect_on_association(name))
         end
         clone

spec/mongoid/criterion/inclusion_spec.rb

@@ -636,6 +636,129 @@
       Person.create
     end
 
+    context "when providing inclusions to the default scope" do
+
+      before do
+        Person.default_scope(Person.includes(:posts))
+      end
+
+      after do
+        Person.default_scoping = nil
+      end
+
+      let!(:post_one) do
+        person.posts.create(:title => "one")
+      end
+
+      let!(:post_two) do
+        person.posts.create(:title => "two")
+      end
+
+      context "when the criteria has no options" do
+
+        before do
+          Mongoid::IdentityMap.clear
+        end
+
+        let!(:criteria) do
+          Person.all.entries
+        end
+
+        it "returns the correct documents" do
+          criteria.should eq([ person ])
+        end
+
+        it "inserts the first document into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_one.id].should eq(post_one)
+        end
+
+        it "inserts the second document into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_two.id].should eq(post_two)
+        end
+      end
+
+      context "when calling first on the criteria" do
+
+        before do
+          Mongoid::IdentityMap.clear
+        end
+
+        let!(:from_db) do
+          Person.first
+        end
+
+        it "returns the correct documents" do
+          from_db.should eq(person)
+        end
+
+        it "inserts the first document into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_one.id].should eq(post_one)
+        end
+
+        it "inserts the second document into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_two.id].should eq(post_two)
+        end
+      end
+
+      context "when calling last on the criteria" do
+
+        before do
+          Mongoid::IdentityMap.clear
+        end
+
+        let!(:from_db) do
+          Person.last
+        end
+
+        it "returns the correct documents" do
+          from_db.should eq(person)
+        end
+
+        it "inserts the first document into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_one.id].should eq(post_one)
+        end
+
+        it "inserts the second document into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_two.id].should eq(post_two)
+        end
+      end
+
+      context "when the criteria has limiting options" do
+
+        let!(:person_two) do
+          Person.create
+        end
+
+        let!(:post_three) do
+          person_two.posts.create(:title => "three")
+        end
+
+        before do
+          Mongoid::IdentityMap.clear
+        end
+
+        let!(:criteria) do
+          Person.asc(:_id).limit(1).entries
+        end
+
+        it "returns the correct documents" do
+          criteria.should eq([ person ])
+        end
+
+        it "inserts the first document into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_one.id].should eq(post_one)
+        end
+
+        it "inserts the second document into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_two.id].should eq(post_two)
+        end
+
+        it "does not insert the third post into the identity map" do
+          Mongoid::IdentityMap[Post.collection_name][post_three.id].should be_nil
+        end
+      end
+    end
+
     context "when including a has and belongs to many" do
 
       let!(:preference_one) do