Rails 和 Mongoid 的动态属性

发布于 2024-08-30 00:35:51 字数 717 浏览 5 评论 0原文

我正在通过 Mongoid Ruby gem 和 Rails (Rails 3 beta 3) 学习 MongoDB，并且我试图想出一种方法，在基于另一个模型的字段的模型上创建动态属性，我认为这是一个模式 -较少的数据库将是一个不错的选择。

例如，我有模型：

class Account
  include Mongoid::Document

  field :name, :type => String
  field :token, :type => String
  field :info_needed, :type => Array

  embeds_many :members
end

class Member
  include Mongoid::Document

  embedded_in :account, :inverse_of => :members

end

我希望采用帐户模型的“info_needed”属性，并根据内部内容在会员模型上创建动态属性。如果club.info_needed是[“first_name”，“last_name”]，我试图创建一个将first_name和last_name属性保存到Member模型的表单。

然而，在实践中，当我尝试执行此操作时，我只是在成员模型上不断收到“未定义的方法first_name =”错误。我知道 MongoDB 可以处理每条记录的动态属性，但是如何让 Mongoid 做到这一点而不出现未定义的方法错误？

原文

I'm learning MongoDB through the Mongoid Ruby gem with Rails (Rails 3 beta 3), and I'm trying to come up with a way to create dynamic attributes on a model based on fields from another model, which I thought a schema-less database would be a good choice for.

So for example, I'd have the models:

class Account
  include Mongoid::Document

  field :name, :type => String
  field :token, :type => String
  field :info_needed, :type => Array

  embeds_many :members
end

class Member
  include Mongoid::Document

  embedded_in :account, :inverse_of => :members

end

I'm looking to take the "info_needed" attribute of the Account model and created dynamic attributes on the Member model based on what's inside. If club.info_needed was ["first_name", "last_name"], I'm trying to create a form that would save first_name and last_name attributes to the Member model.

However, upon practice, I just keep getting "undefined method first_name=" errors on the Member model when trying to do this. I know MongoDB can handle dynamic attributes per record, but how can I get Mongoid to do this without an undefined method error?

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涫野音 2024-09-06 00:35:51

Mongoid 现在支持动态字段。他们的文档可以在这里找到：
http://mongoid.org/en/mongoid/docs/documents.html#dynamic_fields基本上

，它警告您必须稍微小心如何设置动态字段，因为如果您尝试对文档中不存在的字段使用 getter 和 setter 方法，则会引发无方法错误。

[],[]= 是 read_attribute(),write_attribute() 的快捷方式，如果您未在 ./config/mongoid.yml 文件中设置 dynamic_attributes = true ，则应使用它们< /code> ，否则你会得到一个 no method 错误。

设置 allow_dynamic_fields: true 可能存在风险，因为代码中的错误可能会导致意外字段污染您的数据/架构。将其设置为 false 并显式使用 [],[]= 可能更安全

# Raise a NoMethodError if value isn't set.
person.gender
person.gender = "Male"

# Retrieve a dynamic field safely.
person[:gender]
person.read_attribute(:gender)

# Write a dynamic field safely.
person[:gender] = "Male"
person.write_attribute(:gender, "Male")

Mongoid now supports Dynamic Fields. Their documentation can be found here:
http://mongoid.org/en/mongoid/docs/documents.html#dynamic_fields

Basically it warns that you have to be slightly careful how you set dynamic fields as it will raise a no method error if you attempt to use the getter and setter methods for a field that did not exist in the document.

[],[]= are shortcuts for read_attribute(),write_attribute() , and should be used if you do not set dynamic_attributes = true in your ./config/mongoid.yml file , otherwise you'll get a no method error.

Setting allow_dynamic_fields: true can be risky, as you might pollute your data/schema with unintended fields caused by bugs in your code. It's probably safer to set this to false and explicitly use [],[]=

# Raise a NoMethodError if value isn't set.
person.gender
person.gender = "Male"

# Retrieve a dynamic field safely.
person[:gender]
person.read_attribute(:gender)

# Write a dynamic field safely.
person[:gender] = "Male"
person.write_attribute(:gender, "Male")

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乄_柒ぐ汐 2024-09-06 00:35:51

请务必在 mongoid.yml 中设置 allow_dynamic_fields: true。例子：

defaults: &defaults
  allow_dynamic_fields: true
  parameterize_keys: true
  persist_in_safe_mode: true
  raise_not_found_error: true
  reconnect_time: 3
  use_object_ids: false

development:
  <<: *defaults

...

Be sure to set allow_dynamic_fields: true in mongoid.yml. Example:

defaults: &defaults
  allow_dynamic_fields: true
  parameterize_keys: true
  persist_in_safe_mode: true
  raise_not_found_error: true
  reconnect_time: 3
  use_object_ids: false

development:
  <<: *defaults

...

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