find_by

# File activerecord/lib/active_record/core.rb, line 186
      def find_by(*args) # :nodoc:
        return super if scope_attributes? || reflect_on_all_aggregations.any? ||
                        columns_hash.key?(inheritance_column) && base_class != self

        hash = args.first

        return super if !(Hash === hash) || hash.values.any? { |v|
          StatementCache.unsupported_value?(v)
        }

        # We can't cache Post.find_by(author: david) ...yet
        return super unless hash.keys.all? { |k| columns_hash.has_key?(k.to_s) }

        keys = hash.keys

        statement = cached_find_by_statement(keys) { |params|
          wheres = keys.each_with_object({}) { |param, o|
            o[param] = params.bind
          }
          where(wheres).limit(1)
        }
        begin
          statement.execute(hash.values, connection).first
        rescue TypeError
          raise ActiveRecord::StatementInvalid
        rescue ::RangeError
          nil
        end
      end