在Bryan Helmkamp的一篇名为" 7 Patterns to Refactor Fat ActiveRecord Models"的优秀博文中,他提到使用Form Objects
抽象出多层表格并停止使用{{1} }。
修改:请参阅below了解解决方案。
我几乎完全重复了他的代码示例,因为我有同样的问题需要解决:
accepts_nested_attributes_for
我的代码中不同的一点是,我需要验证帐户名称(和用户电子邮件)的唯一性。但是,class Signup
include Virtus
extend ActiveModel::Naming
include ActiveModel::Conversion
include ActiveModel::Validations
attr_reader :user
attr_reader :account
attribute :name, String
attribute :account_name, String
attribute :email, String
validates :email, presence: true
validates :account_name,
uniqueness: { case_sensitive: false },
length: 3..40,
format: { with: /^([a-z0-9\-]+)$/i }
# Forms are never themselves persisted
def persisted?
false
end
def save
if valid?
persist!
true
else
false
end
end
private
def persist!
@account = Account.create!(name: account_name)
@user = @account.users.create!(name: name, email: email)
end
end
没有ActiveModel::Validations
验证程序,因为它应该是uniqueness
的非数据库支持变体。
我认为有三种方法可以解决这个问题:
我更愿意使用最后一个。但后来我一直想知道 我将如何实现这一点。
我可以做一些像(元编程,我需要修改其他一些区域):
ActiveRecord
但是现在我在我的班级中运行了两个检查,首先我使用 def persist!
@account = Account.create!(name: account_name)
@user = @account.users.create!(name: name, email: email)
rescue ActiveRecord::RecordNotUnique
errors.add(:name, "not unique" )
false
end
然后我使用valid?
语句来处理数据存储限制。
有谁知道处理这个问题的好方法?或许为此编写我自己的验证器会更好(但是我对数据库有两个查询,理想情况下一个就足够了)。
答案 0 :(得分:8)
布莱恩对comment on my question to his blog post很友善。在他的帮助下,我想出了以下自定义验证器:
class UniquenessValidator < ActiveRecord::Validations::UniquenessValidator
def setup(klass)
super
@klass = options[:model] if options[:model]
end
def validate_each(record, attribute, value)
# UniquenessValidator can't be used outside of ActiveRecord instances, here
# we return the exact same error, unless the 'model' option is given.
#
if ! options[:model] && ! record.class.ancestors.include?(ActiveRecord::Base)
raise ArgumentError, "Unknown validator: 'UniquenessValidator'"
# If we're inside an ActiveRecord class, and `model` isn't set, use the
# default behaviour of the validator.
#
elsif ! options[:model]
super
# Custom validator options. The validator can be called in any class, as
# long as it includes `ActiveModel::Validations`. You can tell the validator
# which ActiveRecord based class to check against, using the `model`
# option. Also, if you are using a different attribute name, you can set the
# correct one for the ActiveRecord class using the `attribute` option.
#
else
record_org, attribute_org = record, attribute
attribute = options[:attribute].to_sym if options[:attribute]
record = options[:model].new(attribute => value)
super
if record.errors.any?
record_org.errors.add(attribute_org, :taken,
options.except(:case_sensitive, :scope).merge(value: value))
end
end
end
end
您可以在ActiveModel类中使用它,如下所示:
validates :account_name,
uniqueness: { case_sensitive: false, model: Account, attribute: 'name' }
您唯一的问题是,如果您的自定义model
类也有验证。当您致电Signup.new.save
时,不会运行这些验证,因此您必须以其他方式检查这些验证。您始终可以在上述save(validate: false)
方法中使用persist!
,但是您必须确保所有验证都在Signup
课程中,并且在您更改任何课程时保持该课程的最新状态Account
或User
中的验证。
答案 1 :(得分:8)
如果这恰好是一次性要求,那么创建自定义验证器可能会过度。
简化方法......
class Signup
(...)
validates :email, presence: true
validates :account_name, length: {within: 3..40}, format: { with: /^([a-z0-9\-]+)$/i }
# Call a private method to verify uniqueness
validate :account_name_is_unique
def persisted?
false
end
def save
if valid?
persist!
true
else
false
end
end
private
# Refactor as needed
def account_name_is_unique
unless Account.where(name: account_name).count == 0
errors.add(:account_name, 'Account name is taken')
end
end
def persist!
@account = Account.create!(name: account_name)
@user = @account.users.create!(name: name, email: email)
end
end