redis/redis-rb · error · TypeError

by must be an Integer (BYINT) or a Float (BYFLOAT), got #{by

Error message

by must be an Integer (BYINT) or a Float (BYFLOAT), got #{by.class}

What it means

Error "by must be an Integer (BYINT) or a Float (BYFLOAT), got #{by.class}" thrown in redis/redis-rb.

Source

Thrown at lib/redis/commands/strings.rb:130

      #   `ex`/`px`/`exat`/`pxat`
      # @return [Array(Integer, Integer), Array(Float, Float)]
      #   `[new_value, applied_increment]` — Integers in integer mode, Floats
      #   in float mode (under RESP2 and RESP3 alike); `applied_increment`
      #   is 0 when the operation was skipped as out of bounds
      def increx(key, by: nil, lbound: nil, ubound: nil, saturate: nil,
                 ex: nil, px: nil, exat: nil, pxat: nil, persist: nil, enx: nil)
        if [ex, px, exat, pxat, persist].count { |option| option } > 1
          raise ArgumentError, "ex, px, exat, pxat and persist are mutually exclusive"
        end
        raise ArgumentError, "enx is incompatible with persist" if enx && persist
        raise ArgumentError, "enx requires one of ex, px, exat or pxat" if enx && !(ex || px || exat || pxat)

        # The Ruby type of `by` selects the wire mode; anything else would
        # have to silently pick a mode, so it is rejected instead.
        float_mode = case by
        when nil, Integer then false
        when Float then true
        else raise TypeError, "by must be an Integer (BYINT) or a Float (BYFLOAT), got #{by.class}"
        end

        args = [:increx, key]
        args << (float_mode ? "BYFLOAT" : "BYINT") << by if by
        args << "LBOUND" << increx_bound(:lbound, lbound, float_mode) if lbound
        args << "UBOUND" << increx_bound(:ubound, ubound, float_mode) if ubound
        args << "SATURATE" if saturate
        args << "EX" << Integer(ex) if ex
        args << "PX" << Integer(px) if px
        args << "EXAT" << Integer(exat) if exat
        args << "PXAT" << Integer(pxat) if pxat
        args << "PERSIST" if persist
        args << "ENX" if enx

        if float_mode
          # RESP2 replies with bulk strings, RESP3 with native doubles;
          # converge both on Float.
          send_command(args) { |reply| reply.is_a?(Array) ? reply.map(&Floatify) : reply }

View on GitHub (pinned to 2ba9010b91)

Solutions

1. Pass by: as an Integer for BYINT or a Float for BYFLOAT, e.g. by: 2 or by: 0.5.
2. Coerce the value with to_i or to_f before calling if it arrives as a string.

When it happens

Trigger: Thrown at lib/redis/commands/strings.rb:130 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of redis/redis-rb@2ba9010b91 (2026-08-23). Data as JSON: /api/errors/f6356329fd0e3b7b. Report an issue: GitHub.