Refactored the path calculators in action_view_extension to expose the path_to_next_page and path_to_prev_page

kaminari-actionview/lib/kaminari/actionview/action_view_extension.rb

@@ -44,9 +44,9 @@ module Kaminari
     #     <span>At the Beginning</span>
     #   <% end %>
     def link_to_previous_page(scope, name, options = {})
-      prev_page = Kaminari::Helpers::PrevPage.new self, options.reverse_merge(:current_page => scope.current_page)
+      prev_page = path_to_prev_page(scope, options)
 
-      link_to_if scope.prev_page.present?, name, prev_page.url, options.except(:params, :param_name).reverse_merge(:rel => 'prev') do
+      link_to_if prev_page, name, prev_page, options.except(:params, :param_name).reverse_merge(:rel => 'prev') do
         yield if block_given?
       end
     end
@@ -69,9 +69,9 @@ module Kaminari
     #     <span>No More Pages</span>
     #   <% end %>
     def link_to_next_page(scope, name, options = {})
-      next_page = Kaminari::Helpers::NextPage.new self, options.reverse_merge(:current_page => scope.current_page)
+      next_page = path_to_next_page(scope, options)
 
-      link_to_if scope.next_page.present?, name, next_page.url, options.except(:params, :param_name).reverse_merge(:rel => 'next') do
+      link_to_if next_page, name, next_page, options.except(:params, :param_name).reverse_merge(:rel => 'next') do
         yield if block_given?
       end
     end
@@ -127,15 +127,43 @@ module Kaminari
     #   #-> <link rel="next" href="/items/page/3" /><link rel="prev" href="/items/page/1" />
     #
     def rel_next_prev_link_tags(scope, options = {})
-      next_page = Kaminari::Helpers::NextPage.new self, options.reverse_merge(:current_page => scope.current_page)
-      prev_page = Kaminari::Helpers::PrevPage.new self, options.reverse_merge(:current_page => scope.current_page)
+      next_page = path_to_next_page(scope, options)
+      prev_page = path_to_prev_page(scope, options)
 
       output = String.new
-      output << tag(:link, :rel => "next", :href => next_page.url) if scope.next_page.present?
-      output << tag(:link, :rel => "prev", :href => prev_page.url) if scope.prev_page.present?
+      output << tag(:link, :rel => "next", :href => next_page) if next_page
+      output << tag(:link, :rel => "prev", :href => prev_page) if prev_page
       output.html_safe
     end
 
+    # A helper that calculates the path to the next page.
+    #
+    # ==== Examples
+    # Basic usage:
+    #
+    #   <%= path_to_next_page @items %>
+    #   #-> /items?page=2
+    #
+    # It will return `nil` if there is no next page.
+    def path_to_next_page(scope, options = {})
+      return nil unless scope.next_page.present?
+      Kaminari::Helpers::NextPage.new(self, options.reverse_merge(:current_page => scope.current_page)).url
+    end
+
+    # A helper that calculates the path to the previous page.
+    #
+    # ==== Examples
+    # Basic usage:
+    #
+    #   <%= path_to_prev_page @items %>
+    #   #-> /items
+    #
+    # It will return `nil` if there is no previous page.
+    def path_to_prev_page(scope, options = {})
+      return nil unless scope.prev_page.present?
+      Kaminari::Helpers::PrevPage.new(self, options.reverse_merge(:current_page => scope.current_page)).url
+    end
+
     module PaginatorExtension
       extend ActiveSupport::Concern
 

kaminari-core/spec/helpers/action_view_extension_spec.rb

@@ -368,4 +368,45 @@ describe 'Kaminari::ActionViewExtension', :if => defined?(::Rails::Railtie) && d
       it { should_not match(/rel="next"/) }
     end
   end
+
+  describe '#path_to_next_page' do
+    before do
+      2.times {|i| User.create! :name => "user#{i}"}
+    end
+
+    subject { helper.path_to_next_page users, :params => {:controller => 'users', :action => 'index'} }
+
+    context 'the first page' do
+      let(:users) { User.page(1).per(1) }
+      it { should eql '/users?page=2' }
+    end
+
+    context 'the last page' do
+      let(:users) { User.page(2).per(1) }
+      it { should be nil }
+    end
+  end
+
+  describe '#path_to_prev_page' do
+    before do
+      3.times {|i| User.create! :name => "user#{i}"}
+    end
+
+    subject { helper.path_to_prev_page users, :params => {:controller => 'users', :action => 'index'} }
+
+    context 'the first page' do
+      let(:users) { User.page(1).per(1) }
+      it { should be nil }
+    end
+
+    context 'the second page' do
+      let(:users) { User.page(2).per(1) }
+      it { should eql '/users' }
+    end
+
+    context 'the last page' do
+      let(:users) { User.page(3).per(1) }
+      it { should eql '/users?page=2' }
+    end
+  end
 end