gistfile1.rb

    open_study = Study.where(status: "Open to Accrual").first
    fields = [self.status, self.date, open_study, open_study.date]
    if((self.status != "Open to Accrual") && (fields.all?(&:present?)) && (self.date < open_study.date))
      errors.add(:date, :greater_than_open_date)
    end

    #VS

    open_study = Study.where(status: "Open to Accrual").first
    unless self.status == "Open to Accrual"
      if self.status && self.date && open_study && open_study.date
        if self.date < open_study.date
          errors.add(:date, :greater_than_open_date)
        end
      end
    end