模型验证无法在rails app中运行

Question

我在我的一个模型中进行了验证:( sku_code验证。）

class Vendor < ActiveRecord::Base
  has_many :purchases

  validates :name, format: {with: /\A[A-Za-z0-9\S\s]+\z/, message: "Vendor name is invalid."}
  validates :sku_code, format: {with: /\A[A-Z]{3}\z/, message: "must follow format ABC"}

end

控制器：

class VendorsController < ApplicationController
  def index
    @vendors = Vendor.all

    respond_to do |format|
      format.js
      format.html
      format.json
    end
  end

  def new
    @vendor = Vendor.new

    respond_to do |format|
      format.js
      format.html
      format.json
    end
  end

  def create
    @vendor = Vendor.new(vendor_params)

    respond_to do |format|
      if @vendor.save
        format.html { redirect_to @vendor, notice: 'Vendor successfully created.' }
        format.js   {}
        format.json { render json: @vendor, status: :created, location: @vendor }
      else
        format.html { render 'new' }
        format.json { render json: @vendor.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    @vendor = Vendor.find(params[:id])

    respond_to do |format|
      if @vendor.update(vendor_params)
        format.html { redirect_to @vendor, notice: 'Vendor successfully updated.' }
        format.js   {}
        format.json { render json: @vendor, status: :updated, location: @vendor }
      else
        format.html { render 'edit' }
        format.json { render json: @vendor.errors, status: :unprocessable_entity }
      end
    end
  end

  def edit
    @vendor = Vendor.find(params[:id])

    respond_to do |format|
      format.js
      format.html
      format.json
    end
  end

  def destroy
    @vendor = Vendor.find(params[:id])
    @vendor.destroy
    #flash.notice="Vendor '#{@vendor.name}' was deleted."
    redirect_to action: "index"
  end

  def show
    @vendor = Vendor.find(params[:id])

    respond_to do |format|
      format.js
      format.html
      format.json
    end
  end

  private
    def vendor_params
      params.require(:vendor).permit(:name, :sku_code, :contact, :phone, :email, :address_line1, :address_line2, :address_city, :address_state, :address_zip, :address_country, :lead_time)
    end
end

我对这个正则表达式的期望是它允许将三个大写字母字符串输入到我的表单中但是阻止其他任何内容。

目前它正在拒绝三个大写字母字符串。

我在这里做错了什么？