如何在 Rails 模型验证中编写正则表达式？

首先，新方法不会在对象上触发任何类型的验证。

class Person < ApplicationRecord
  validates :name, presence: true
end

>> p = Person.new
# => #<Person id: nil, name: nil>
>> p.errors.messages
# => {}

new method does not trigger any validation on an object as it is not hitting the database to save the record. 
>> p.save
# => false

save method will try to create the record to the database and triggers the respective validation on the object.


>> p.valid?
# => false

When you hit the .valid? the method, it validates the object against the mentioned validation.

>> p.errors.messages
# => {name:["can't be blank"]}

>> p = Person.create
# => #<Person id: nil, name: nil>

Creating and saving a new record will send an SQL INSERT operation to the database.

Internal functionality of Person.create is Person.new and Person.save

When you are creating an object, it tries to create the valid record to the database and triggers the respective validation.

>> p.errors.messages
# => {name:["can't be blank"]}

>> p.save
# => false

>> p.save!
# => ActiveRecord::RecordInvalid: Validation failed: Name can't be blank

>> Person.create!
# => ActiveRecord::RecordInvalid: Validation failed: Name can't be blank

其次，validates_numericality_of和validates_format_of是您混合使用的不同验证助手集。

  validates_numericality_of :my_attr, :only_integer => true, :allow_blank => true,
                            :greater_than => 0

validates_format_of :my_attr, :without => /(\d:\d|^\p{L}+$)/

This validation won't accept any such object :
MyObjectTime.new({:my_attr => "ab"})
MyObjectTime.new({:my_attr => "1:1"})

有关更多信息，您可以从这些验证助手中获取帮助 => http://api.rubyonrails.org/classes/ActiveModel/Validations/HelperMethods.html