Adding initial pagination support based on kaminari

lib/couchrest/model/designs.rb

@@ -21,6 +21,8 @@ module CouchRest
 
       module ClassMethods
 
+        # Add views and other design document features
+        # to the current model.
         def design(*args, &block)
           mapper = DesignMapper.new(self)
           mapper.create_view_method(:all)
@@ -30,6 +32,23 @@ module CouchRest
           req_design_doc_refresh
         end
 
+        # Override the default page pagination value:
+        #
+        #   class Person < CouchRest::Model::Base
+        #     paginates_per 10
+        #   end
+        #
+        def paginates_per(val)
+          @_default_per_page = val
+        end
+
+        # The models number of documents to return
+        # by default when performing pagination.
+        # Returns 25 unless explicitly overridden via <tt>paginates_per</tt>
+        def default_per_page
+          @_default_per_page || 25
+        end
+
       end
 
       # 

lib/couchrest/model/designs/view.rb

@@ -14,7 +14,7 @@ module CouchRest
       class View
         include Enumerable
 
-        attr_accessor :model, :name, :query, :result
+        attr_accessor :owner, :model, :name, :query, :result
 
         # Initialize a new View object. This method should not be called from
         # outside CouchRest Model.
@@ -22,11 +22,13 @@ module CouchRest
           if parent.is_a?(Class) && parent < CouchRest::Model::Base
             raise "Name must be provided for view to be initialized" if name.nil?
             self.model    = parent
+            self.owner    = parent
             self.name     = name.to_s
             # Default options:
             self.query    = { :reduce => false }
           elsif parent.is_a?(self.class)
             self.model    = (new_query.delete(:proxy) || parent.model)
+            self.owner    = parent.owner
             self.name     = parent.name
             self.query    = parent.query.dup
           else
@@ -175,7 +177,6 @@ module CouchRest
         # are combined in an incorrect fashion.
         #
 
-
         # Find all entries in the index whose key matches the value provided.
         #
         # Cannot be used when the +#startkey+ or +#endkey+ have been set.
@@ -300,6 +301,46 @@ module CouchRest
           @docs = nil
         end
 
+        # == Kaminari compatible pagination support
+        #
+        # Based on the really simple support for scoped pagination in the
+        # the Kaminari gem, we provide compatible methods here to perform
+        # the same actions you'd expect.
+        #
+
+        alias :total_count :count
+
+        def page(page)
+          limit(owner.default_per_page).skip(owner.default_per_page * ([page.to_i, 1].max - 1))
+        end
+
+        def per(num)
+          raise "View#page must be called before #per!" if limit_value.nil? || offset_value.nil?
+          if (n = num.to_i) <= 0
+            self
+          else
+            limit(num).skip(offset_value / limit_value * n)
+          end
+        end
+
+        def offset_value
+          query[:skip]
+        end
+
+        def limit_value
+          query[:limit]
+        end
+
+        def num_pages
+          (total_count.to_f / limit_value).ceil
+        end
+
+        def current_page
+          (offset_value / limit_value) + 1
+        end
+
+
+
         protected
 
         def include_docs!

spec/couchrest/designs/view_spec.rb

@@ -541,6 +541,53 @@ describe "Design View" do
 
       end
 
+      describe "pagination methods" do
+
+        describe "#total_count" do
+          it "should be an alias for count" do
+            @obj.method(:total_count).should eql(@obj.method(:count))
+          end
+        end
+
+        describe "#page" do
+          it "should call limit and skip" do
+            @obj.should_receive(:limit).with(25).and_return(@obj)
+            @obj.should_receive(:skip).with(25).and_return(@obj)
+            @obj.page(2)
+          end
+        end
+
+        describe "#per" do
+          it "should raise an error if page not called before hand" do
+            lambda { @obj.per(12) }.should raise_error
+          end
+          it "should not do anything if number less than or eql 0" do
+            view = @obj.page(1)
+            view.per(0).should eql(view)
+          end
+          it "should set limit and update skip" do
+            view = @obj.page(2).per(10)
+            view.query[:skip].should eql(10)
+            view.query[:limit].should eql(10)
+          end
+        end
+
+        describe "#num_pages" do
+          it "should use total_count and limit_value" do
+            @obj.should_receive(:total_count).and_return(200)
+            @obj.should_receive(:limit_value).and_return(25)
+            @obj.num_pages.should eql(8)
+          end
+        end
+
+        describe "#current_page" do
+          it "should use offset and limit" do
+            @obj.should_receive(:offset_value).and_return(25)
+            @obj.should_receive(:limit_value).and_return(25)
+            @obj.current_page.should eql(2)
+          end
+        end
+      end
     end
   end
 

spec/couchrest/designs_spec.rb

@@ -10,8 +10,9 @@ describe "Design" do
     DesignModel.respond_to?(:design).should be_true
   end
 
-  describe ".design" do
+  describe "class methods" do
 
+    describe ".design" do
       before :each do 
         @mapper = mock('DesignMapper')
         @mapper.stub!(:create_view_method)
@@ -37,6 +38,20 @@ describe "Design" do
 
     end
 
+    describe "default_per_page" do
+      it "should return 25 default" do
+        DesignModel.default_per_page.should eql(25)
+      end
+    end
+
+    describe ".paginates_per" do
+      it "should set the default per page value" do
+        DesignModel.paginates_per(21)
+        DesignModel.default_per_page.should eql(21)
+      end
+    end
+  end
+
   describe "DesignMapper" do
     
     before :all do