Hacking ActiveRecord:添加全局命名作用域
Hacking ActiveRecord:添加全局命名作用域
提问于 2010-09-30 17:02:38
我正在尝试为ActiveRecord模型提供一组非常通用的命名作用域，如下所示：
module Scopes
def self.included(base)
base.class_eval do
named_scope :not_older_than, lambda {|interval|
{:conditions => ["#{table_name}.created_at >= ?", interval.ago]
}
end
end
end
ActiveRecord::Base.send(:include, Scopes)
class User < ActiveRecord::Base
end如果命名作用域应该是一般的，我们需要指定*table_name*，以防止来自其他链式命名作用域的is连接出现命名问题。
问题是我们无法获取table_name，因为它是在ActiveRecord::Base上调用的，而不是在User上调用的。
User.not_older_than(1.week)
NoMethodError: undefined method `abstract_class?' for Object:Class
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:2207:in `class_of_active_record_descendant'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1462:in `base_class'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1138:in `reset_table_name'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1134:in `table_name'
from /home/bogdan/makabu/railsware/startwire/repository/lib/core_ext/active_record/base.rb:15:in `included'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/named_scope.rb:92:in `call'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/named_scope.rb:92:in `named_scope'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/named_scope.rb:97:in `call'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/named_scope.rb:97:in `not_older_than'如何在Scopes模块中获得实际的table_name？
回答 4
Stack Overflow用户
回答已采纳
发布于 2018-02-28 12:25:49
Rails 5，ApplicationRecord (希望它能帮助其他人)
# app/models/concerns/not_older_than.rb
module NotOlderThan
extend ActiveSupport::Concern
included do
scope :not_older_than, -> (time, table = self.table_name){
where("#{table}.created_at >= ?", time.ago)
}
end
end
# app/models/application_record.rb
class ApplicationRecord < ActiveRecord::Base
self.abstract_class = true
include NotOlderThan
end
# app/models/user.rb
class User < ApplicationRecord
# Code
end
# Usage
User.not_older_than(1.week)在Rails5中，默认情况下所有模型都继承自ApplicationRecord。如果您希望将此范围仅应用于特定模型集，请仅将include语句添加到这些模型类。这也适用于连接查询和链接作用域。
Stack Overflow用户
发布于 2010-09-30 17:38:03
尝试在ActiveRecord::Base的类方法中使用#scoped方法。这应该是可行的：
module Scopes
def self.included(base)
base.class_eval do
def self.not_older_than(interval)
scoped(:conditions => ["#{table_name}.created_at > ?", interval.ago])
end
end
end
end
ActiveRecord::Base.send(:include, Scopes)Stack Overflow用户
发布于 2014-04-24 05:26:19
下面是其他有用的作用域：
module Scopes
def self.included(base)
base.class_eval do
def self.created(date_start, date_end = nil)
if date_start && date_end
scoped(:conditions => ["#{table_name}.created_at >= ? AND #{table_name}.created_at <= ?", date_start, date_end])
elsif date_start
scoped(:conditions => ["#{table_name}.created_at >= ?", date_start])
end
end
def self.updated(date_start, date_end = nil)
if date_start && date_end
scoped(:conditions => ["#{table_name}.updated_at >= ? AND #{table_name}.updated_at <= ?", date_start, date_end])
elsif date_start
scoped(:conditions => ["#{table_name}.updated_at >= ?", date_start])
end
end
end
end
end
ActiveRecord::Base.send(:include, Scopes)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/3829174
复制相关文章
相似问题
腾讯云开发者
