basic question about belongs_to

rubyonrails-talk
1

Hello,

I've got three tables:

site { id name, customer_id }

building { id, site_id, name }

equipment { id, building_id, name }

In my building model I have "belongs_to :site" and in my equipment model I have "belongs_to :building".

How do I find all pieces of equipment that belong to a particular customer?

I tried something like Equipment.find(:all, :include => [ :building, :site ], :conditions => 'customer_id = 1'), but of course that doesn't work because there's nothing about :site in the equipment model. I also tried to put ":include => :site" in the "belongs_to" in the building model, but I got an error saying that the association named ":site" wasn't found.

Any ideas?

Thanks!

2

Hello,

I've got three tables:

site { id name, customer_id }

building { id, site_id, name }

equipment { id, building_id, name }

Where's Customer?

In my building model I have "belongs_to :site" and in my equipment model I have "belongs_to :building".

How do I find all pieces of equipment that belong to a particular customer?

Do you also have: class Site    has_many :buildings end and so on?

I tried something like Equipment.find(:all, :include => [ :building, :site ], :conditions => 'customer_id = 1'), but of course that doesn't work because there's nothing about :site in the equipment model. I also tried to put ":include => :site" in the "belongs_to" in the building model, but I got an error saying that the association named ":site" wasn't found.

Any ideas?

Thanks!

Your table names should be plural (e.g., 'sites' and 'buildings') unless you have overridden this with set_table_name in your model.

You can also try:

Equipment.find(:all, :include => { :building => :site },                 :conditions => [ 'site.customer_id = ?', some_customer ])

but even if that works as-is, you should consider the other parts (adding "has_many" associations to mirror your "belongs_to"; having a customer model and table; pluralizing your tables) as means to avoid future aggravation.

-Rob

Rob Biedenharn http://agileconsultingllc.com Rob@AgileConsultingLLC.com

3

Where's Customer?

I tried to shorten my question, that's why I didn't show all the relevant relationships. I do have the customer model.

Your table names should be plural (e.g., 'sites' and 'buildings')

They are. They aren't in the example though. Good catch :slight_smile:

Equipment.find(:all, :include => { :building => :site }

This worked like a charm. I need to read about that variation of :include. Cool!

(adding "has_many" associations to mirror your "belongs_to"; having a

Well, so far I haven't needed to reverse. Is that a no-no not to mirror it?

Thanks Rob. You saved me a lot of searching. Much appreciate.

4

Well, so far I haven't needed to reverse. Is that a no-no not to

I meant to say "I haven't needed the reverse relationship"