#1677 Association proxies using class methods with named scopes - Ruby on Rails

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#1677 ✓resolved

Association proxies using class methods with named scopes

Reported by Matt Jankowski | December 31st, 2008 @ 03:54 PM | in 2.x

I believe this occurs in both 2.0 and 2.2.

When you attempt to chain named_scopes together in a class method, and then call that class method through an association proxy, the conditions from the association proxy are not applied unless the class method ends with a call to #all when using the named scopes. Simple example follows...

Class definitions...



  class Event

    belongs_to :hub

    def self.upcoming_with_all(limit = nil)
      public.ending_after(Time.now.utc).published.limited(limit).ordered.all
    end

    def self.upcoming_without_all(limit = nil)
      public.ending_after(Time.now.utc).published.limited(limit).ordered
    end
  
  end

  class Hub
    has_many :events
  end

Console output...



  >> Hub.first.events.upcoming_with_all(2)
    Hub Load (0.7ms)   SELECT * FROM `hubs` LIMIT 1
    Event Load (1.0ms)   SELECT * FROM `events` WHERE ((((`events`.hub_id = 1) 
    AND (events.published = 1)) AND (events.ends_at > '2008-12-29 21:17:50')) 
    AND ((not events.private))) ORDER BY events.created_on desc LIMIT 2

  >> Hub.first.events.upcoming_without_all(2)
    Hub Load (0.3ms)   SELECT * FROM `hubs` LIMIT 1
    SQL (345.4ms)   SELECT count(*) AS count_all FROM `events` 
    WHERE (((events.published = 1) AND (events.ends_at > '2008-12-29 21:17:55')) 
    AND ((not events.private))) LIMIT 2

Note how the first version, whose class method has an #all call on the end of the scope chain, correctly uses the condition that comes from the association (ie, it limits to a certain hub), but the second version does not.

Comments and changes to this ticket

Frederick Cheung December 31st, 2008 @ 05:00 PM
I think I understand why this is. I setup User has_many posts, post has a named_scope called active.

When you do
```
User.last.posts.active
```
Then active is called on the association proxy, and method missing on the association proxy knows that if you call :foo on it and :foo is a named scope on the parent then it should call that scope on itself (ie the named scope is called with proxy_scope set to the association proxy)

When you do
```
class Post
  def self.class_method
    active
  end
end
User.last.posts.class_method
```
Then the active method is called on class Post, not the association proxy and so the named scope is called with proxy_scope set to Post, not the association proxy.

The association proxy wraps the call to class_method in a with_scope with the conditions so if class_method does a find then it will execute inside the with_scope block and everything is fine. But if it just invokes a scope upon which a find is done later then that find is executed outside the with_scope and so everything falls to pieces.
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Diego Algorta February 20th, 2009 @ 01:56 PM
I think my patch on #1960 fixes this.
Repository February 25th, 2009 @ 05:13 PM
- State changed from “new” to “resolved”
(from [a9aa18fdcdf3146ccbdecff71e52015f26a0f0b7]) Fixed bug that makes named_scopes forgot current scope

Signed-off-by: rick technoweenie@gmail.com [#1960 #1677 state:resolved] http://github.com/rails/rails/co...
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