extract_value_from_default

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 525
        def extract_value_from_default(oid, default) # :nodoc:
          case default
            # Quoted types
            when /\A[\(B]?'(.*)'::/
              $1.gsub(/''/, "'")
            # Boolean types
            when 'true', 'false'
              default
            # Numeric types
            when /\A\(?(-?\d+(\.\d*)?)\)?(::bigint)?\z/
              $1
            # Object identifier types
            when /\A-?\d+\z/
              $1
            else
              # Anything else is blank, some user type, or some function
              # and we can't know the value of that, so return nil.
              nil
          end
        end