诗歌rails之Rails验证的示例

先补充一个部分的代码用来说明这些回调在一些实际中的用法，

Ruby代码

class Profile < ActiveRecord::Base
before_validation :archive#在验证之前判断，
#为什么验证之前呢，因为如果是新建的话就不要验证了
before_destroy :destroy_validate#删除的时候验证
def archive
return unless self.new_record?
profile = Profile.find_by_name(self.name)
unless profile.nil?
profile.name = sprintf("a-%s", profile.id)
profile.status = true
unless profile.save
return false
end
end
end
def validate#修改默认的验证
errors.add(:major_offset, "must be >= Minor Offset") unless major_offset >= minor_offset
errors.add(:minor_offset, "must be <= Major Offset") unless minor_offset <= major_offset
if Analyzer.count(:conditions => ["profile_id = ? and status= ?", self.id, Analyzer::INGRESS]) > 0
errors.add_to_base("One or more Analyzers are in Ingress Monitoring mode and use this profile. Edits are disabled until you stop Ingress Monitoring.")
return false
end
end
def destroy_validate#对应删除验证的描述
if Analyzer.count(:conditions => ["profile_id = ? ", self.id]) > 0
errors.add_to_base("One or more Analyzers use this profile, Delete are disabled.")
return false
end
if SwitchPort.exists?(:profile_id=> self.id)
errors.add_to_base("One or more Analyzers use this profile, Delete are disabled.")
return false
end
end
end

class Profile < ActiveRecord::Base
  before_validation :archive#在验证之前判断，
  #为什么验证之前呢，因为如果是新建的话就不要验证了
  before_destroy :destroy_validate#删除的时候验证
  def archive
    return unless self.new_record?
    profile = Profile.find_by_name(self.name)
    unless profile.nil?
      profile.name = sprintf("a-%s", profile.id)
      profile.status = true
      unless profile.save 
        return false
      end
    end
  end
  def validate#修改默认的验证
    errors.add(:major_offset, "must be >= Minor Offset") unless major_offset >= minor_offset
    errors.add(:minor_offset, "must be <= Major Offset") unless minor_offset <= major_offset
     if Analyzer.count(:conditions => ["profile_id = ? and status= ?", self.id, Analyzer::INGRESS]) > 0
      errors.add_to_base("One or more Analyzers are in Ingress Monitoring mode and use this profile.  Edits are disabled until you stop Ingress Monitoring.")
      return false
    end
  end
  def destroy_validate#对应删除验证的描述
    if Analyzer.count(:conditions => ["profile_id = ? ", self.id]) > 0
      errors.add_to_base("One or more Analyzers use this profile, Delete are disabled.")
      return false
    end
    if SwitchPort.exists?(:profile_id=> self.id)
      errors.add_to_base("One or more Analyzers use this profile, Delete are disabled.")
      return false
    end
  end
end

通常在一个active record对象的生命周期里，有八个过程

引用

(-) save
(-) valid?
(1) before_validation
(2) before_validation_on_create
(-) validate
(-) validate_on_create
(3) after_validation
(4) after_validation_on_create
(5) before_save
(6) before_create
(-) create
(7) after_create
(8) after_save

这些stat是可以用来hook
下面是一个

回调的典型例子

Ruby代码

class CreditCard < ActiveRecord::Base
# 这个例子用来说明预先处理信用卡数据，作用是在验证
# 以前把输入的数据中不是数字的输入，屏蔽掉。就是把 "555 234 34"或者
# "5552-3434" 都转换成 "55523434"
def before_validation_on_create
self.number = number.gsub(/[^0-9]/, "") if attribute_present?("number")
end
end
class Subscription < ActiveRecord::Base
#这是另一个回调的例子，是在创建的时候，积累时间。
#当然，这里是示例，没有人需要这个功能
before_create :record_signup
private
def record_signup
self.signed_up_on = Date.today
end
end
class Firm < ActiveRecord::Base
# 下面的例子也经常用就是相关删除。很多时候，这件事应该是dependent => :destroy
# 来完成，当然，还有些时候比较复杂的回调，就会用到类似的方法
# 当firm公司删除时，同时删除对应员工（Person）和客户（Client）
before_destroy { |record| Person.destroy_all "firm_id = #{record.id}" }
before_destroy { |record| Client.destroy_all "client_of = #{record.id}" }
end

  class CreditCard < ActiveRecord::Base
    # 这个例子用来说明预先处理信用卡数据，作用是在验证
    # 以前把输入的数据中不是数字的输入，屏蔽掉。就是把 "555 234 34"或者
    # "5552-3434" 都转换成 "55523434"
    def before_validation_on_create
      self.number = number.gsub(/[^0-9]/, "") if attribute_present?("number")
    end
  end

 
  class Subscription < ActiveRecord::Base
    #这是另一个回调的例子，是在创建的时候，积累时间。
    #当然，这里是示例，没有人需要这个功能
    before_create :record_signup

    private
      def record_signup
        self.signed_up_on = Date.today
      end
  end

  class Firm < ActiveRecord::Base
    # 下面的例子也经常用就是相关删除。很多时候，这件事应该是dependent => :destroy
    # 来完成，当然，还有些时候比较复杂的回调，就会用到类似的方法
    # 当firm公司删除时，同时删除对应员工（Person）和客户（Client）
    before_destroy { |record| Person.destroy_all "firm_id = #{record.id}"   }
    before_destroy { |record| Client.destroy_all "client_of = #{record.id}" }
  end

有继承关系的回调

下面的情景是说，当在一个类中定义了回调。但，他有一个子类，又定义了一个回调。
然后，我们希望，
有些时候，回调继承执行。就是又要执行父类的回调，又要执行子类的回调。
有些时候，希望子类的回调，重写覆盖父类的回调。
那么，看看如何实现

Ruby代码

#这样的话，将实现回调的继承和队列调用
class Topic < ActiveRecord::Base
before_destroy :destroy_author
end
class Reply < Topic
before_destroy :destroy_readers
end
#也就是说，当Topic#destroy调用的时候 destroy_author将被执行。而，当Topic#destroy被执行的时候destroy_author和 destroy_readers将都被调用
#-------------------------------------------------------------------------
#下面的方法，将导致覆盖
class Topic < ActiveRecord::Base
def before_destroy() destroy_author end
end
class Reply < Topic
def before_destroy() destroy_readers end
end
#这个时候，当Reply#destroy被调用时候将只调用destroy_readers将不会调用 destroy_author.
#-------------------------------------------------------------------------

#这样的话，将实现回调的继承和队列调用
  class Topic < ActiveRecord::Base
    before_destroy :destroy_author
  end

  class Reply < Topic
    before_destroy :destroy_readers
  end
#也就是说，当Topic#destroy调用的时候 destroy_author将被执行。而，当Topic#destroy被执行的时候destroy_author和 destroy_readers将都被调用
#-------------------------------------------------------------------------
#下面的方法，将导致覆盖
class Topic < ActiveRecord::Base
    def before_destroy() destroy_author end
  end

  class Reply < Topic
    def before_destroy() destroy_readers end
  end
#这个时候，当Reply#destroy被调用时候将只调用destroy_readers将不会调用 destroy_author.
#-------------------------------------------------------------------------

回调的四种类型

Method references (符号),
callback objects（最常用吧）,
inline methods (使用块方法),
and inline eval methods (字符串).

在这其中，前两种是推荐的回调表达方式。块方法的回调有些时候，也比较合适。最后的一种，基本废弃。

Ruby代码

class Topic < ActiveRecord::Base
#这是标准的使用，把回调的方法本身，限制为private或者protected
before_destroy :delete_parents
private
def delete_parents
self.class.delete_all "parent_id = #{id}"
end
end

  class Topic < ActiveRecord::Base
    #这是标准的使用，把回调的方法本身，限制为private或者protected 
    before_destroy :delete_parents

    private
      def delete_parents
        self.class.delete_all "parent_id = #{id}"
      end
  end

回调的参数

回调方法的参数，是记录，根据传入的不同，灵活调用。

Ruby代码

class BankAccount < ActiveRecord::Base
before_save EncryptionWrapper.new("credit_card_number")
after_save EncryptionWrapper.new("credit_card_number")
after_initialize EncryptionWrapper.new("credit_card_number")
end
class EncryptionWrapper
def initialize(attribute)
@attribute = attribute
end
def before_save(record)
record.credit_card_number = encrypt(record.credit_card_number)
end
def after_save(record)
record.credit_card_number = decrypt(record.credit_card_number)
end
alias_method :after_find, :after_save
private
def encrypt(value)
# Secrecy is committed
end
def decrypt(value)
# Secrecy is unveiled
end
end

  class BankAccount < ActiveRecord::Base
    before_save      EncryptionWrapper.new("credit_card_number")
    after_save       EncryptionWrapper.new("credit_card_number")
    after_initialize EncryptionWrapper.new("credit_card_number")
  end

  class EncryptionWrapper
    def initialize(attribute)
      @attribute = attribute
    end

    def before_save(record)
      record.credit_card_number = encrypt(record.credit_card_number)
    end

    def after_save(record)
      record.credit_card_number = decrypt(record.credit_card_number)
    end

    alias_method :after_find, :after_save

    private
      def encrypt(value)
        # Secrecy is committed
      end

      def decrypt(value)
        # Secrecy is unveiled
      end
  end

method missing的应用

回调的宏，默认下会等待一个符号，但当我们在符号部分，使用method missing时，就可以在预期估值的时候，执行绑定的回调。

Ruby代码

class Topic < ActiveRecord::Base
#实现act as tree的级联删除
before_destroy 'self.class.delete_all "parent_id = #{id}"'
end
class Topic < ActiveRecord::Base
before_destroy 'self.class.delete_all "parent_id = #{id}"',
'puts "Evaluated after parents are destroyed"'
end

  class Topic < ActiveRecord::Base
    #实现act as tree的级联删除
    before_destroy 'self.class.delete_all "parent_id = #{id}"'
  end
  class Topic < ActiveRecord::Base
    before_destroy 'self.class.delete_all "parent_id = #{id}"',
                   'puts "Evaluated after parents are destroyed"'
  end

* after_create
* after_destroy
* after_save
* after_update
* after_validation
* after_validation_on_create
* after_validation_on_update
* before_create
* before_destroy
* before_save
* before_update
* before_validation
* before_validation_on_create
* before_validation_on_update

http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html

posted @ 2009-08-18 15:21 麦飞阅读(600) 评论(0) 编辑收藏举报

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