Question

如果值为nil或空白，

The uniqueness validator of ActiveRecord可以选择跳过验证。即使我将两个参数都设置为true（默认行为），我也可以在验证命中之前创建一个nil和空白的记录。我使用默认的SQlite3数据库sqlite3-ruby（1.2.5）。

编辑以澄清：如果我将validates_presence_of添加到模型中，我会得到预期的结果。我认为validates_uniqueness_of的默认行为会使这种情况变得多余。

测试用例：

rails validation_test
cd validation_test/
script/generate Model Thing identification:string
rake db:migrate

app / models / thing.rb的内容：

class Thing < ActiveRecord::Base
  validates_uniqueness_of :identification
end

Rails控制台：

script/console 
Loading development environment (Rails 2.3.4)
>> Thing.create!
=> #<Thing id: 1, identification: nil, created_at: "2009-09-26 01:49:32", updated_at: "2009-09-26 01:49:32">
>> Thing.create! :identification => ""
=> #<Thing id: 2, identification: "", created_at: "2009-09-26 01:49:42", updated_at: "2009-09-26 01:49:42">
>> Thing.create! :identification => ""
ActiveRecord::RecordInvalid: Validation failed: Identification has already been taken
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/validations.rb:1090:in `save_without_dirty!'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/dirty.rb:87:in `save_without_transactions!'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in `save!'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in `transaction'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:182:in `transaction'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in `save!'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:208:in `rollback_active_record_state!'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in `save!'
    from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/validations.rb:1059:in `create!'
    from (irb):3
>> Thing.count
=> 2

为什么前两个创作通过？

由于

Answer 1

您错误地认为是默认行为。来自the docs：

:allow_nil - If set to true, skips this validation if the attribute is nil (default is false).
:allow_blank - If set to true, skips this validation if the attribute is blank (default is false).

将这两个设置为true，我在Rails 2.3.4中看到以下行为。

class Thing < ActiveRecord::Base
  validates_uniqueness_of :identification, :allow_blank => true, :allow_nil => true
end

>> Thing.create! :identification => ""
=> #<Thing id: 6, identification: "", created_at: "2009-09-26 03:09:48", updated_at: "2009-09-26 03:09:48">
>> Thing.create! :identification => ""
=> #<Thing id: 7, identification: "", created_at: "2009-09-26 03:09:49", updated_at: "2009-09-26 03:09:49">
>> Thing.create! :identification => nil
=> #<Thing id: 8, identification: nil, created_at: "2009-09-26 03:09:52", updated_at: "2009-09-26 03:09:52">
>> Thing.create! :identification => nil
=> #<Thing id: 9, identification: nil, created_at: "2009-09-26 03:09:53", updated_at: "2009-09-26 03:09:53">

编辑：解决您的澄清问题。 添加validates_presence_of对于您尝试执行的操作是正确的。这不是多余的，因为它正在检查完全不同的错误情况。它也有自己的错误信息，这对用户来说很重要。

class Thing < ActiveRecord::Base
  validates_uniqueness_of :identification, :allow_nil => true, :allow_blank => true
  validates_presence_of :identification
end

Answer 2

并带有validates：

validates :email, uniqueness: { allow_blank: true }
# or
validates :email, uniqueness: { allow_nil: true }

validates_uniqueness_of传递nil或空白（不带allow_nil和allow_blank）

2 个答案: