Is there an idiomatic way to cut out the middle-man in a join in Rails?
We have a Customer model, which has a lot of has_many relations, e.g. to CustomerCountry and CustomerSetting.  Often, we need to join these relations to each other; e.g. to find the settings of customers in a given country.  The normal way of expressing this would be something like

    CustomerSetting.find :all,
                         :joins => {:customer => :customer_country},
                         :conditions => ['customer_countries.code = ?', 'us']

but the equivalent SQL ends up as

    SELECT ... FROM customer_settings 
    INNER JOIN customers ON customer_settings.customer_id = customers.id
    INNER JOIN customer_countries ON customers.id = customer_countries.customer_id

when what I really want is 

    SELECT ... FROM customer_settings
    INNER JOIN countries ON customer_settings.customer_id = customer_countries.customer_id

I can do this by explicitly setting the :joins SQL, but is there an idiomatic way to specify this join?
Is there an idiomatic way to cut out the middle-man in a join in Rails?
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We have a Customer model, which has a lot of has_many relations, e.g. to CustomerCountry and CustomerSetting.  Often, we need to join these relations to each other; e.g. to find the settings of customers in a given country.  The normal way of expressing this would be something like

    CustomerSetting.find :all,
                         :joins => {:customer => :customer_country},
                         :conditions => ['customer_countries.code = ?', 'us']

but the equivalent SQL ends up as

    SELECT ... FROM customer_settings 
    INNER JOIN customers ON customer_settings.customer_id = customers.id
    INNER JOIN customer_countries ON customers.id = customer_countries.customer_id

when what I really want is 

    SELECT ... FROM customer_settings
    INNER JOIN countries ON customer_settings.customer_id = customer_countries.customer_id

I can do this by explicitly setting the :joins SQL, but is there an idiomatic way to specify this join?