instance method unescape_bytea

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 309
      def unescape_bytea(value)
        # In each case, check if the value actually is escaped PostgreSQL bytea output
        # or an unescaped Active Record attribute that was just written.
        if PGconn.respond_to?(:unescape_bytea)
          self.class.instance_eval do
            define_method(:unescape_bytea) do |value|
              if value =~ /\\\d{3}/
                PGconn.unescape_bytea(value)
              else
                value
              end
            end
          end
        else
          self.class.instance_eval do
            define_method(:unescape_bytea) do |value|
              if value =~ /\\\d{3}/
                result = ''
                i, max = 0, value.size
                while i < max
                  char = value[i]
                  if char == ?\\
                    if value[i+1] == ?\\
                      char = ?\\
                      i += 1
                    else
                      char = value[i+1..i+3].oct
                      i += 3
                    end
                  end
                  result << char
                  i += 1
                end
                result
              else
                value
              end
            end
          end
        end
        unescape_bytea(value)
      end