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:
