新手问题 [已解决] custom validator 在 model 保存后报错
Rails 版本 6.0.1
- user.rb
class DateValidator < ActiveModel::EachValidator
def validate_each(record, attribute, value)
rawValue = record.send(attribute.to_s + '_before_type_cast')
if (Date.parse(rawValue) rescue ArgumentError) == ArgumentError
record.errors.add attribute, :data_error
end
end
end
class User < ApplicationRecord
validates :date_of_birth, date: true
end
- rails console:
irb(main):001:0> user = User.new date_of_birth: '2020-02-02'
irb(main):002:0> user.valid?
=> true
irb(main):003:0> user.save
(0.2ms) BEGIN
User Create (0.3ms) INSERT INTO "users" ("date_of_birth") VALUES ($1, $2, $3) RETURNING "id" [["date_of_birth", "2020-02-02"], ["created_at", "2020-02-24 05:12:27.657736"], ["updated_at", "2020-02-24 05:12:27.657736"]]
(0.9ms) COMMIT
=> true
irb(main):004:0> user.valid?
=> false
irb(main):005:0> user.errors
=> #<ActiveModel::Errors:0x00005606b0872eb0 @base=#<User id: 1, date_of_birth: "2020-02-02", created_at: "2020-02-24 05:12:27", updated_at: "2020-02-24 05:12:27">, @messages={:date_of_birth=>["日期有误"]}, @details={:date_of_birth=>[{:error=>:data_error}]}>
谁知道到底哪里出了问题？
jasl
#1
2020年02月25日
如果你想校验日期格式 https://github.com/adzap/validates_timeliness 用这个就好
如果你要想练习，最简单的办法就是，你先搞明白 rawValue = record.send(attribute.to_s + '_before_type_cast') 出来的值和类型是什么
（取 attribute.to_s + '_before_type_cast' 的意图没看懂）
puts rawValue
puts rawValue.class
看一看
继续，做做测试，比如
2.6.5 :009 > User.first.created_at_before_type_cast
User Load (0.5ms) SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT $1 [["LIMIT", 1]]
=> 2020-02-22 16:33:42 UTC
2.6.5 :010 > Date.parse User.first.created_at_before_type_cast
User Load (0.5ms) SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT $1 [["LIMIT", 1]]
Traceback (most recent call last):
2: from (irb):10
1: from (irb):10:in `parse'
TypeError (no implicit conversion of Time into String)
2.6.5 :011 > Date.parse User.first.created_at.to_date
User Load (0.5ms) SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT $1 [["LIMIT", 1]]
Traceback (most recent call last):
3: from (irb):11
2: from (irb):11:in `rescue in irb_binding'
1: from (irb):11:in `parse'
TypeError (no implicit conversion of Date into String)
可见字段类型如果是 Datetime 甚至就是 Date 一样可以引发异常，这明显违背了这个验证器的意图。
这里正确的做法是用专门的库（开头提了），或者利用 ActiveRecord::Type
2.6.5 :012 > ActiveRecord::Type.lookup(:date).cast("x")
=> nil
2.6.5 :014 > ActiveRecord::Type.lookup(:date).cast('2020-02-02')
=> Sun, 02 Feb 2020
2.6.5 :015 > ActiveRecord::Type.lookup(:date).cast(Date.today)
=> Tue, 25 Feb 2020
2.6.5 :016 > ActiveRecord::Type.lookup(:date).cast(Time.now)
=> Tue, 25 Feb 2020
那么只要判断返回值是否为 nil，即可判定了
对
jasl
回复
jasl
回复
我明白了，在第一次新建模型 create 的时候 rawValue 获取到的是用户 input 输入，是 String。保存之后变成 Date 或者 DateTime，此时如果再去验证这个用户实例，获取到的 rawValue 就是保存后的 Date 或者 DateTime 格式了。
的确是验证器逻辑有问题，感谢建议！
