Use mongo Collection#find_first where appropriate. Close cursor in fi…

…nd_froom_ids.

README.rdoc

@@ -13,7 +13,8 @@ database.yml file. See below for instructions.
 
 == Installing
 
-As noted above, this plugin requires the "mongo" Ruby Gem.
+As noted above, this plugin requires the "mongo" Ruby Gem, version 0.5.4 or
+higher.
 
 To add this plugin to your Rails app, move (or link) this directory into your
 Rails app's vendor/plugins directory and name it mongo_record. In other words,

init.rb

@@ -6,7 +6,11 @@
 db_config = db_config[RAILS_ENV]
 
 if db_config['adapter'] == 'mongo'
-  require 'mongo'
+  begin
+    require 'mongo >= 0.5.4'
+  rescue
+    require 'mongo'
+  end
   require 'mongo_record/pk_factory'
   require 'mongo_record'
   $db = XGen::Mongo::Driver::Mongo.new(db_config['host'], db_config['port']).db(db_config['database'], :pk => MongoRecord::PKFactory.new)

lib/mongo_record/active_record/base.rb

@@ -176,7 +176,7 @@ def count_by_sql(sql)
       # that needs to list both the number of posts and comments.
       def increment_counter(counter_name, id)
         sel = {:_id => id}
-        rec = collection.find(sel, :limit => 1).next_object
+        rec = collection.find_first(sel, :limit => 1)
         raise "counter named \"#{counter_name}\" was not found" unless rec
         rec[counter_name.to_s] += 1
         collection.replace(sel, rec)
@@ -185,7 +185,7 @@ def increment_counter(counter_name, id)
       # Works like increment_counter, but decrements instead.
       def decrement_counter(counter_name, id)
         sel = {:_id => id}
-        rec = collection.find(sel, :limit => 1).next_object
+        rec = collection.find_first(sel, :limit => 1)
         raise "counter named \"#{counter_name}\" was not found" unless rec
         rec[counter_name.to_s] -= 1
         collection.replace(sel, rec)
@@ -230,7 +230,7 @@ def sanitize(object) #:nodoc:
       def find_initial(options)
         criteria = criteria_from(options[:conditions]).merge(where_func(options[:where]))
         fields = fields_from(options[:select])
-        row = collection.find(criteria, :fields => fields, :limit => 1).next_object
+        row = collection.find_first(criteria, :fields => fields, :limit => 1)
         (row.nil? || row['_id'] == nil) ? nil : self.send(:instantiate, row)
       end
 
@@ -247,7 +247,13 @@ def find_from_ids(ids, options)
         criteria[:_id] = ids_clause(ids)
         options = rails_to_mongo_find_options(options)
         db_cursor = collection.find(criteria, options)
-        ids.length == 1 ? instantiate(db_cursor.next_object) : MongoRecord::Cursor.new(db_cursor, self)
+        if ids.length == 1
+          row = db_cursor.next_object
+          db_cursor.close
+          instantiate(row)
+        else
+          MongoRecord::Cursor.new(db_cursor, self)
+        end
       end
 
       def ids_clause(ids)