compatible with composite_primary_keys gem #214

lib/bullet/ext/object.rb

@@ -4,7 +4,9 @@ def bullet_key
   end
 
   def primary_key_value
-    if self.class.respond_to?(:primary_key) && self.class.primary_key
+    if self.class.respond_to?(:primary_keys) && self.class.primary_keys
+      self.class.primary_keys.map { |primary_key| self.send primary_key }.join(',')
+    elsif self.class.respond_to?(:primary_key) && self.class.primary_key
       self.send self.class.primary_key
     else
       self.id

spec/bullet/ext/object_spec.rb

@@ -25,7 +25,12 @@
       post = Post.first
       Post.primary_key = 'name'
       expect(post.primary_key_value).to eq(post.name)
-      Post.primary_key = 'id'
+    end
+
+    it "should return value for multiple primary keys" do
+      post = Post.first
+      allow(Post).to receive(:primary_keys).and_return([:category_id, :writer_id])
+      expect(post.primary_key_value).to eq("#{post.category_id},#{post.writer_id}")
     end
   end
 end