fix paginated Relation count & empty? methods

closes mislav#145

lib/will_paginate/active_record.rb

@@ -64,17 +64,25 @@ def total_entries
           if loaded? and size < limit_value and (current_page == 1 or size > 0)
             offset_value + size
           else
-            excluded = [:order, :limit, :offset]
-            excluded << :includes unless eager_loading?
-            rel = self.except(*excluded)
-            # TODO: hack. decide whether to keep
-            rel = rel.apply_finder_options(@wp_count_options) if defined? @wp_count_options
             @total_entries_queried = true
-            rel.count
+            count
           end
         end
       end
 
+      def count
+        if limit_value
+          excluded = [:order, :limit, :offset]
+          excluded << :includes unless eager_loading?
+          rel = self.except(*excluded)
+          # TODO: hack. decide whether to keep
+          rel = rel.apply_finder_options(@wp_count_options) if defined? @wp_count_options
+          rel.count
+        else
+          super
+        end
+      end
+
       # workaround for Active Record 3.0
       def size
         if !loaded? and limit_value
@@ -84,6 +92,15 @@ def size
         end
       end
 
+      # overloaded to be pagination-aware
+      def empty?
+        if !loaded? and offset_value
+          count <= offset_value
+        else
+          super
+        end
+      end
+
       def total_pages
         (total_entries / limit_value.to_f).ceil
       end

spec/finders/active_record_spec.rb

@@ -53,6 +53,19 @@
       rel.per_page.should == 5
     end
 
+    it "remembers pagination in sub-relations" do
+      rel = Topic.paginate(:page => 2, :per_page => 3)
+      lambda {
+        rel.total_entries.should == 4
+      }.should run_queries(1)
+      rel = rel.mentions_activerecord
+      rel.current_page.should == 2
+      rel.per_page.should == 3
+      lambda {
+        rel.total_entries.should == 1
+      }.should run_queries(1)
+    end
+
     it "supports the page() method" do
       rel = Developer.page('1').order('id')
       rel.current_page.should == 1
@@ -82,13 +95,6 @@
   end
 
   describe "counting" do
-    it "should not accept :count parameter" do
-      pending
-      lambda {
-        User.paginate :page => 1, :count => {}
-      }.should raise_error(ArgumentError)
-    end
-
     it "should guess the total count" do
       lambda {
         topics = Topic.paginate :page => 2, :per_page => 3
@@ -111,6 +117,13 @@
       }.should run_queries(2)
     end
 
+    it "supports empty? method" do
+      topics = Topic.paginate :page => 1, :per_page => 3
+      lambda {
+        topics.should_not be_empty
+      }.should run_queries(1)
+    end
+
     it "overrides total_entries count with a fixed value" do
       lambda {
         topics = Topic.paginate :page => 1, :per_page => 3, :total_entries => 999