Question

I have two basic models: Stadium and Owner

The relations between those two models are:

A Stadium:

belongs_to :owner

An Owner:

has_many :stadiums

The thing here is, an Owner has also Categories associated, and here is where owner_category model comes in.

An Owner:

has_and_belongs_to_many :owner_categories,
                          :join_table => 'l_owners_owner_categories',

And OwnerCategory:

has_and_belongs_to_many :owners, :join_table => 'l_owners_owner_categories'

Basically,

The OwnerCategory table looks like this:

id,name
1,sport
2,kids

So, my question is:

Given that I let the user to choose a City and a Category, how would I get all the Stadiums from that city which Owner has the given Category?

So for example:

If I have the following Stadiums:

id,name,city,owner_id
1,'soccer stadium','New York',5
2,'music stadium','New York',4
2,'music stadium','San Francisco',4

The following Owners:

id,name
4, 'John'
5, 'Peter'

The following OwnersCategories table:

id,name,description
1,'sports','this category is associated with stadiums that support sports'
2,'music','this category is associated with stadiums that support music'

And the following join table:

owner_id,owner_category_id
 5, 1

When the users chooses ‘New York’ and ‘Sports’ it should give this stadium:

 1,'soccer stadium','New York',5

Answer 1

Try something like this (warning: not tested):

Stadium.joins(:owner).joins(:owner => :owner_categories)
.where(:city => "New York").where("owners_categories.name = ?", "sports")