faker-ruby/faker · error · ArgumentError

Day of week cannot be empty

Error message

Day of week cannot be empty

What it means

Error "Day of week cannot be empty" thrown in faker-ruby/faker.

Source

Thrown at lib/faker/default/date.rb:158

      ##
      # Produce a random date at given day(s) of the week between two dates.
      #
      # @param day [Symbol, Array<Symbol>] # The day(s) of the week. See {DAYS_OF_WEEK}.
      # @param from [Date, String] The start of the usable date range.
      # @param to [Date, String] The end of the usable date range.
      # @return [Date]
      #
      # @example if used with or without Rails (Active Support)
      #   Faker::Date.on_day_of_week_between(day: :tuesday, from: '2023-01-01', to: '2023-02-01') #=> #<Date: 2032-01-10>
      #
      # @example if used with Rails (Active Support)
      #   Faker::Date.on_day_of_week_between(day: [:saturday, :sunday], from: 1.month.ago, to: Date.today) #=> #<Date: 2014-09-24>
      #
      # @faker.version next
      def on_day_of_week_between(day:, from:, to:)
        days = [day].flatten
        raise ArgumentError, 'Day of week cannot be empty' if days.empty?

        # Convert given days of the week to numbers used by `Date#wday` method
        numeric_weekdays = days.map do |d|
          DAYS_OF_WEEK.index(d.to_sym.downcase) || raise(ArgumentError, "#{d} is not a valid day of the week")
        end

        from = get_date_object(from)
        to   = get_date_object(to)
        date = Faker::Base.rand_in_range(from, to)

        # If the initial date is not on one of the wanted days of the week...
        unless numeric_weekdays.include? date.wday
          # ...pick a date nearby that is on one of the wanted days of the week instead
          date += sample(numeric_weekdays) - date.wday

          # Move date 1 week earlier or later if the adjusted date is now outside the date range
          date += 7 if date < from
          date -= 7 if date > to

View on GitHub (pinned to cca4184947)

When it happens

Trigger: Thrown at lib/faker/default/date.rb:158 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of faker-ruby/faker@cca4184947 (2026-08-21). Data as JSON: /api/errors/e4b895b8e4abd7ce. Report an issue: GitHub.