Add the ability to keep params in the link to first page

fixes #44

lib/kaminari/config.rb

@@ -25,6 +25,7 @@ module Kaminari
     config_accessor :right
     config_accessor :page_method_name
     config_accessor :max_pages
+    config_accessor :params_on_first_page
 
     def param_name
       config.param_name.respond_to?(:call) ? config.param_name.call : config.param_name
@@ -47,5 +48,6 @@ module Kaminari
     config.page_method_name = :page
     config.param_name = :page
     config.max_pages = nil
+    config.params_on_first_page = false
   end
 end

lib/kaminari/helpers/sinatra_helpers.rb

@@ -45,7 +45,7 @@ module Kaminari::Helpers
 
       def url_for(params)
         extra_params = {}
-        if page = params[@param_name] and page != 1
+        if (page = params[@param_name]) && (Kaminari.config.params_on_first_page || page != 1)
           extra_params[@param_name] = page
         end
         query = @current_params.merge(extra_params)

lib/kaminari/helpers/tags.rb

@@ -37,7 +37,7 @@ module Kaminari
         page_params = Rack::Utils.parse_nested_query("#{@param_name}=#{page}")
         page_params = @params.with_indifferent_access.deep_merge(page_params)
 
-        if page <= 1
+        if !Kaminari.config.params_on_first_page && page <= 1
           # This converts a hash:
           #   from: {other: "params", page: 1}
           #     to: {other: "params", page: nil}

spec/config/config_spec.rb

@@ -2,6 +2,7 @@ require 'spec_helper'
 
 describe Kaminari::Configuration do
   subject { Kaminari.config }
+
   describe 'default_per_page' do
     context 'by default' do
       its(:default_per_page) { should == 25 }
@@ -88,4 +89,21 @@ describe Kaminari::Configuration do
       end
     end
   end
+
+  describe 'params_on_first_page' do
+    context 'by default' do
+      its(:params_on_first_page) { should be_false }
+    end
+
+    context 'configure via config block' do
+      before do
+        Kaminari.configure {|c| c.params_on_first_page = true }
+      end
+      after do
+        Kaminari.configure {|c| c.params_on_first_page = false }
+      end
+
+      its(:params_on_first_page) { should be_true }
+    end
+  end
 end

spec/helpers/tags_spec.rb

@@ -4,6 +4,19 @@ include Kaminari::Helpers
 describe 'Kaminari::Helpers' do
   describe 'Tag' do
     describe '#page_url_for', :if => defined?(Rails) do
+      before { helper.request.assign_parameters(_routes, "users", "index") }
+
+      context "for first page" do
+        subject { Tag.new(helper).page_url_for(1) }
+        it { should == "/users" }
+
+        context 'config.params_on_first_page == false' do
+          before { Kaminari.config.params_on_first_page = true }
+          after  { Kaminari.config.params_on_first_page = false }
+          it { should == "/users?page=1" }
+        end
+      end
+
       context "with a friendly route setting" do
         before do
           helper.request.assign_parameters(_routes, "addresses", "index", :page => 3)
@@ -12,6 +25,12 @@ describe 'Kaminari::Helpers' do
         context "for first page" do
           subject { Tag.new(helper).page_url_for(1) }
           it { should == "/addresses" }
+
+          context 'config.params_on_first_page == false' do
+            before { Kaminari.config.params_on_first_page = true }
+            after  { Kaminari.config.params_on_first_page = false }
+            it { should match("/addresses/page/1") }
+          end
         end
 
         context "for other page" do
@@ -22,7 +41,6 @@ describe 'Kaminari::Helpers' do
 
       context "with param_name = 'user[page]' option" do
         before do
-          helper.request.assign_parameters(_routes, "users", "index")
           helper.params.merge!(:user => {:page => "3", :scope => "active"})
         end