rails中validates及各种方法

首先是不为空validates :name,presence:{message:'blank is not allowed'}

唯一性：validates :name,uniqueness:{message:'already exist!',case_sensitive: false}#case_sensitive区分大小写

长度：validates :name,length:{in: 6..20,message:'must in 6-20 byte'}


格式：validates :name,format:{with: /[a-z]/,message:'must contain at least one lower case character'}


范围：validates :country,inclusion:{in:['China','USA','Jpan','Mexico'],message:'must one of China USA Jpan Mexico '}


数字：validates :graduate,numericality:{allow_nil: true,greater_than: 1920,less_than_or_equal_to:Time.now.year}






validates :description,presence:true,if: :require_description_presence?


def require_description_presence?

      self.can_send_mail


end


这个validates :description,presence: true只有在require_description_presence?方法返回true的时候才会起作用



validate :description_length_words

def description_length_words

    unless self.description.blank? then

       num_words = self.description.split.length


       if num_words < 5 then

         self.errors.add(:description,'must be at least 5 words long')


       elsif num_words > 50


          self.errors.add(:description,'must be at most 50 words long')


        end


    end


end





validates_exclusion_of 是和validates_inclusion_of相反的！