Help with Associations in Rails 3

Ruby: 1.9.2

Rails: 3.0beta3

I need some help with associations in Rails 3.

I have the following models (see excerpts below):

School, State, SchoolLocale

The schools table has the following fields:

id, name, state_id, school_locale_id

The states table has the following fields:

id, abbr, name

The school_locales table has the following fields:

id, code, name

Unfortunately, my data-source didn't have IDs for school_locales. Thus, the data stored in the 'school_locale_id' field in the schools table actually maps to the 'code' field in the school_locales table.

school.rb:

class School < ActiveRecord::Base
    belongs_to :state
    belongs_to :school_locale
end

sta开发者_如何学运维te.rb:

class State < ActiveRecord::Base
    has_many :schools
end

school_locale.rb:

class SchoolLocale < ActiveRecord::Base
    has_many :schools
end

I would like a query for a given school, let's say School.find(1), that would output the school name, the state name and the school-locale name. I assume that I need to add an index to the 'code' field in the school_locales table and somehow specify it as a foreign key, but I'm not certain. Any help would be appreciated.

This doesn't exactly answer your question, but I think it is a useful bit of information. Regarding your use of a states table, let me refer to Surrogate Vs. Natural/Business Keys.

@Ted says here:

Remember there is nothing special about a primary key, except that it is labelled as such. It is nothing more than a NOT NULL UNIQUE constraint, and a table can have more than one.

If you use a surrogate key, you still want a business key to ensure uniqueness according to the business rules.

There's no point in having a state_id foreign key that links to a states table. Each state already has a unique id; its 2-letter abbreviation. This unique id is just as good as a numeric one. And because this data doesn't change often, there's no harm in having it statically defined within your application somewhere.

I'm not really sure about it, but you could try using this:

class SchoolLocale < ActiveRecord::Base
    has_many :schools, :primary_key => :code
end

Let me know if it works :]