导轨如果指定的has_many制定者应该设置条件 [英] rails has_many setter should set conditions if specified

问题描述

这似乎是对我在Rails中的一个错误，但有可能是没有多少我能做到这一点。所以，我怎么能做到我期望的行为？

This seems like a bug in Rails to me, but there's probably not much I can do about that. So how can I accomplish my expected behavior?

假设我们有：

class User < ActiveRecord::Base
  has_many :awesome_friends, :class_name => "Friend", :conditions => {:awesome => true}
end

和执行code：

>> my_user.awesome_friends << Friend.new(:name=>'jim')

后来，当我检查这个朋友的对象，我看到USER_ID字段填充。但我也希望看到的真棒列设置为真，而事实并非如此。

Afterwards, when I inspect this friend object, I see that the user_id field is populated. But I would also expect to see the "awesome" column set to 'true', which it is not.

此外，如果我执行从控制台执行以下操作：

Furthermore, if I execute the following from the console:

>> my_user.awesome_friends << Friend.new(:name=>'jim')
>> my_user.awesome_friends
= [#<Friend id:1, name:"jim", awesome:nil>]
# Quit and restart the console
>> my_user.awesome_friends
= []

在这个有什么想法？我假设条件散列可以任意复杂，使得融入二传手是不可能的。但在某种程度上，它感觉就像在默认情况下，我们是路过的条件？：user_ID的=> self.id，并获取设置，所以应该不是别人

Any thoughts on this? I suppose the conditions hash could be arbitrarily complex, making integration into the setter impossible. But in a way it feels like by default we are passing the condition ":user_id => self.id", and that gets set, so shouldn't others?

谢谢， 迈克

编辑：

我发现，有回调的has_many，所以我想我可能会这样定义的关系：

I found that there are callbacks for has_many, so I think I might define the relationship like this:

has_many :awesome_friends,
         :class_name => "Friend",
         :conditions => {:awesome => true},
         :before_add => Proc.new{|p,c| c.awesome = true},
         :before_remove => Proc.new{|p,c| c.awesome = false}

尽管，它开始觉得，也许我只是执行一些其他的，现有的设计模式。也许我应该继承AwesomeFriend＆LT;朋友？最终，我需要一些这些的has_many关系，子类获得的凌乱与所有多余的文件。

Although, it's starting to feel like maybe I'm just implementing some other, existing design pattern. Maybe I should subclass AwesomeFriend < Friend? Ultimately I need a couple of these has_many relationships, and subclassing get's messy with all the extra files..

编辑2：

好了，感谢大家谁评论！我最终结束了上面的方法插入一个可爱的小ActiveRecord的扩展，has_many_of_type。其工作方式类似于如下：

Okay, thanks to everyone who commented! I ultimately wrapped up the method above into a nice little ActiveRecord extension, 'has_many_of_type'. Which works like follows:

has_many_of_type :awesome_friends, :class_name => "Friend", :type=>:awesome

刚刚转化为HAS_MANY用适当的条件下，before_add和before_remove PARAMS（并假设一个名为列friend_type的存在）。

Which just translates to has_many with the appropriate conditions, before_add, and before_remove params (and it assumes the existence of a column named friend_type).

推荐答案

您需要使用：

my_user.awesome_friends.create（：名称=＆GT;'吉姆'）或 my_user.awesome_friends.build（：名称=＆GT;吉姆'）

在文档： 的has_many（：条件）

In documentation: has_many (:conditions)

记录从联想的创作范围。的has_many：帖子，：条件=> {：已发布=>真正}将创建发布的文章有@ blog.posts.create或@ blog.posts.build

Record creations from the association are scoped if a hash is used. has_many :posts, :conditions => {:published => true} will create published posts with @blog.posts.create or @blog.posts.build.

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