Added to_xml and ActiveResource deserialization support for empty col…

…lections.

lib/will_paginate/collection.rb

@@ -144,12 +144,17 @@ def replace(array)
     end
 
     def to_xml_with_collection_type(options = {})
-      to_xml_without_collection_type(options) do |xml|
+      serializeable_collection.to_xml_without_collection_type(options) do |xml|
         xml.tag!(:current_page, {:type => ActiveSupport::CoreExtensions::Hash::Conversions::XML_TYPE_NAMES[current_page.class.name]}, current_page)
         xml.tag!(:per_page, {:type => ActiveSupport::CoreExtensions::Hash::Conversions::XML_TYPE_NAMES[per_page.class.name]}, per_page)
         xml.tag!(:total_entries, {:type => ActiveSupport::CoreExtensions::Hash::Conversions::XML_TYPE_NAMES[total_entries.class.name]}, total_entries)
       end.sub(%{type="array"}, %{type="collection"})
     end
     alias_method_chain :to_xml, :collection_type
+
+    def serializeable_collection
+      # Ugly hack because to_xml will not yield the XML Builder object when empty?
+      empty? ? returning(self.clone) { |c| c.instance_eval {|i| def empty?; false; end } } : self
+    end
   end
 end

lib/will_paginate/deserializer.rb

@@ -12,7 +12,7 @@ module ClassMethods
       def instantiate_collection_with_collection(collection, prefix_options = {})
         if collection["type"] == "collection"
           collectables = collection.values.find{|c| c.is_a?(Hash) || c.is_a?(Array) }
-          collectables = [collectables] unless collectables.kind_of?(Array)
+          collectables = [collectables].compact unless collectables.kind_of?(Array)
           instantiated_collection = instantiate_collection_without_collection(collectables, prefix_options = {}).paginate(
             :page => collection["current_page"], 
             :per_page => collection["per_page"], 

test/collection_test.rb

@@ -126,18 +126,22 @@ def test_page_count_was_removed
   end
 
   def test_to_xml_with_blank_collection_type
-    collection = [].paginate(:page => 1, :per_page => 1)
-    assert_select_xml collection.to_xml(:dasherize => false, :root => "rappers"), "rappers[type=?]", "collection"
+    collection = [].paginate(:page => 1, :per_page => 5)
+    assert_select_xml collection.to_xml(:dasherize => false), "nil_classes[type=?]", "collection" do
+      assert_select_xml "current_page[type=?]", "integer", "1"
+      assert_select_xml "per_page[type=?]", "integer", "5"
+      assert_select_xml "total_entries[type=?]", "integer", "0"
+    end
   end
 
   def test_to_xml_with_filled_collection_type
-    collection = [{:word => "up"}].paginate(:page => 1, :per_page => 1)
+    collection = [{:word => "up"}].paginate(:page => 1, :per_page => 5)
     assert_select_xml collection.to_xml(:dasherize => false, :root => "rappers"), "rappers[type=?]", "collection" do |rappers|
       rappers.each do |rapper|
         assert_select_xml "word", "up"
-        assert_select_xml "current_page[type=?]", "integer", 1
-        assert_select_xml "per_page[type=?]", "integer", 1
-        assert_select_xml "total_entries[type=?]", "integer", 1
+        assert_select_xml "current_page[type=?]", "integer", "1"
+        assert_select_xml "per_page[type=?]", "integer", "5"
+        assert_select_xml "total_entries[type=?]", "integer", "1"
       end
     end
   end

test/deserializer_test.rb

@@ -1,7 +1,29 @@
 require 'helper'
 require 'lib/activeresource_test_case'
 
-class DeserializerTest < Test::Unit::TestCase    
+class DeserializerTest < Test::Unit::TestCase  
+  def test_collection_without_entries
+    projects_xml = [].paginate(:page => 1, :per_page => 5).to_xml
+
+    ActiveResource::HttpMock.respond_to do |mock|      
+      mock.get "/projects.xml", {}, projects_xml
+    end
+
+    projects = Client::Project.find(:all) 
+
+    assert projects.kind_of?(WillPaginate::Collection)
+
+    assert_equal 0, projects.size
+
+    assert_equal 1, projects.current_page
+
+    assert_equal 5, projects.per_page
+
+    assert_equal 0, projects.total_entries    
+
+    assert_equal nil, projects.first
+  end
+
   def test_collection_with_one_entry
     projects_xml = [{:name => "will_paginate" }].paginate(:page => 1, :per_page => 5).to_xml(:root => "projects")