验证 :presence 与 validates_presence_of 使用 rails 3 [英] validates :presence vs validates_presence_of using rails 3

问题描述

我有几个简单的模型，它们像这样关联:

I have a couple of simple models that are associated like so:

模型

class Task < ActiveRecord::Base
  belongs_to :user
  validates :name, :presence => true, :message => 'Name cannot be blank, Task not saved'
end

class User < ActiveRecord::Base
  has_many :tasks
end

VIEW 中有一个这样的调用:user.tasks <-- 然后我遍历任务

VIEW has a call in it like so: user.tasks <-- then I loop through the tasks

问题:

在任务模型中 --

当我使用时:

validates :name, :presence => true ,  :message => 'Name cannot be blank, Task not saved'

我收到 500 错误:

I get a 500 error:

ActionView::Template::Error (uninitialized constant User::Task):
NameError in View file

当我使用时:

validates_presence_of :name

一切正常.

我认为上面的两种验证方法都相同……问题与关联以及验证如何与关联模型有关.我有一种预感，即事物的关联方式正在发生变化，但这只是一种预感.

I thought the both validates methods above where the same...is the issue have to do with associations and how validation tie into associated models. I have a hunch that something is going on with the way things are associated, but it is just a hunch.

任何帮助将不胜感激.非常感谢.

Any help will be appreciated. Thank very much.

推荐答案

当您使用较新的 validates :name 格式时，您可以将多个验证放在一行中，而不必将多行用于每种类型的验证.因此，当 Rails 遇到您的 :message 参数时，它会认为这是一种验证方法，而不是与 :presence 关联的消息.试试这个:

When you use the newer validates :name format, you can put multiple validations in one line rather than having to have multiple lines for each type of validation. Because of this, when Rails hits your :message parameter, it thinks it's a validation method rather than a message associated with :presence. Try this instead:

validates :name, :presence => {:message => 'Name cannot be blank, Task not saved'}

此外，根据您显示错误的方式，此错误实际上可能显示为Name Name cannot be...."；如果是这样，您需要将消息设置为不能为空，任务未保存".

Also, depending on how you display your errors, this error may actually show up as 'Name Name cannot be....'; if so, you'll want to set the message to just 'cannot be blank, Task not saved'.

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