Rails - Sep 2008 - Nested has_many :through relations fixed in 2.1.0?

Searching on google yields quite a lot of results describing the
following problems:

class Person < ActiveRecord::Base
  belongs_to :house
end

class House < ActiveRecord::Base
  has_many :people
  belongs_to :city
end

class City < ActiveRecord::Base
  has_many :houses
  has_many :people, :through => :houses
  belongs_to :country
end

class Country < ActiveRecord::Base
  has_many :cities
  has_many :houses, :through => :cities
end

So far so good. Yet, I want to know all the people living in a country.
Creating the following has_many :through relation yields an error on
call: has_many :people, :through => :houses in the Country class. With
the abovementioned code this is only possible by iterating through all
coutry.houses and collecting the house.people.

Aparently in 2006 and 2007 alot of people walked into the same problems,
yet in Rails 2.1.0 I am still unable to make said relation. Is this bug
still not fixed, or am I doing something wrong in calling it?
-- 
Posted via http://www.ruby-forum.com/.

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On Mon, Sep 1, 2008 at 6:03 PM, Chris Dekker <
rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:
>
> Searching on google yields quite a lot of results describing the
> following problems:
>
> class Person < ActiveRecord::Base
>  belongs_to :house
> end
>
> class House < ActiveRecord::Base
>  has_many :people
>  belongs_to :city
> end
>
> class City < ActiveRecord::Base
>  has_many :houses
>  has_many :people, :through => :houses
>  belongs_to :country
> end
>
> class Country < ActiveRecord::Base
>  has_many :cities
>  has_many :houses, :through => :cities
> end
>
> So far so good. Yet, I want to know all the people living in a country.
> Creating the following has_many :through relation yields an error on
> call: has_many :people, :through => :houses in the Country class. With
> the abovementioned code this is only possible by iterating through all
> coutry.houses and collecting the house.people.
>
> Aparently in 2006 and 2007 alot of people walked into the same problems,
> yet in Rails 2.1.0 I am still unable to make said relation. Is this bug
> still not fixed, or am I doing something wrong in calling it?
>
Hi, which statement generates the error?  Do you have foreign keys on both
House and City models?  If not, you should have the following foreign keys:

City:  country_id, house_id

House:  city_id,  person_id

From the above, your join models are House and City.  Thus, I would
recommend working with your City, House, and Person models first.  For
example, you should be able to answer the following questions:

Who lives in CityA?

  city = City.find_by_name( ''CityA'' )
  residents = city.people

Which City does John live?

  john = Person.find_by_name( ''John'' )
  city = john.city

Note:  When attempting to answer these questions, both ends of the
association must have been saved (i.e. committed to the database).  For
example, you''ll need to do the following:

person = Person.create( :name =>  ''John'' )
city = City.create( :name => ''Chicago'' )

city.people << person

After you get this working, then you can start to play with the Country,
City, and House models.  For example, you should be able to answer the
following questions:

What houses are in CountryA?

and so on

Good luck,

-Conrad

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