find_one takes same options as find

lib/mongo/collection.rb

@@ -98,7 +98,8 @@ module XGen
         #   present for a document to be included in the result set OR an
         #   instance of ObjectID to be used as the value for an _id query.
         #   if nil an empty spec, {}, will be used.
-        def find_one(spec_or_object_id=nil)
+        # :options :: options, as passed to Collection#find
+        def find_one(spec_or_object_id=nil, options={})
           spec = case spec_or_object_id
                  when nil
                    {}
@@ -109,7 +110,7 @@ module XGen
                  else
                    raise TypeError, "spec_or_object_id must be an instance of ObjectID or Hash, or nil"
                  end
-          find(spec, :limit => -1).next_object
+          find(spec, options.merge(:limit => -1)).next_object
         end
 
         # DEPRECATED - use find_one instead
@@ -117,10 +118,7 @@ module XGen
         # Find the first record that matches +selector+. See #find.
         def find_first(selector={}, options={})
           warn "Collection#find_first is deprecated and will be removed. Please use Collection#find_one instead."
-          h = options.dup
-          h[:limit] = 1
-          cursor = find(selector, h)
-          cursor.next_object    # don't need to explicitly close b/c of limit
+          find_one(selector, options)
         end
 
         # Save a document in this collection.

tests/test_collection.rb

@@ -88,7 +88,7 @@ class TestCollection < Test::Unit::TestCase
   end
 
   def test_find_one
-    id = @@test.save("hello" => "world")
+    id = @@test.save("hello" => "world", "foo" => "bar")
 
     assert_equal "world", @@test.find_one()["hello"]
     assert_equal @@test.find_one(id), @@test.find_one()
@@ -97,6 +97,9 @@ class TestCollection < Test::Unit::TestCase
     assert_equal @@test.find_one("hello" => "world"), @@test.find_one()
     assert_equal @@test.find_one(OrderedHash["hello", "world"]), @@test.find_one()
 
+    assert @@test.find_one(nil, :fields => ["hello"]).include?("hello")
+    assert !@@test.find_one(nil, :fields => ["foo"]).include?("hello")
+
     assert_equal nil, @@test.find_one("hello" => "foo")
     assert_equal nil, @@test.find_one(OrderedHash["hello", "foo"])
     assert_equal nil, @@test.find_one(ObjectID.new)