I was wondering if it was possible to have rails use an inner/outer join to eager fetch a belongs_to association, rather than having it generate multiple SQL queries?
In this case, here are my model objects with the assoications: class Restaurant < ActiveRecord::Base belongs_to :state end class State < ActiveRecord::Base has_many :restaurants end In my controller action, I am currently doing... @restaurant = Restaurant.find(params[:id], :include => [:state]) ... which is causing multiple SQL queries to be generated, one to select the restaurant info, and the other to select the state info. Is there a way to easily override this default behavior and have rails generate a single query with an INNER or OUTER join while still populating the state info for the restaurant? I did a bit of research on the changes to ActiveRecord between 2.0 and 2.1, and I understand why the default behavior is to generate multiple SQL queries, since in the case where you have a relationship such as has_many that is referenced in the :include, if ActiveRecord were to use a single SQL query, AR might end up having to parse a number of records much larger than the number of distinct rows you will be displaying. I am also aware that if you invoke a condition on a row not in the table corresponding to the model object in the call to find(), that ActiveRecord will fall back on the old method of generating a single query with joins. However, I would prefer to not add any conditions, as that seems like kind of a hack. If absolutely necessary, I suppose I a condition like "states.id = restaurants.state_id" could be added, but that just seems altogether ugly. However, in some cases, such as the one I mention above, I think it might be desirable to be able to ask ActiveRecord to generate a single query, since the result of the SQL would be at most a single row anyhow. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
