has_many belongs_to foreign key question

rubyonrails-talk
1

i have a 2 tables

ITEMS id name attribute_id attribute_secondary_id

ATTRIBUTES id name

what i am trying to do is have attribute_id and attribute_secondary_id both link to the ATTRIBUTES tables. At the moment attribute_id works fine but I'm not sure how i should do the attribute_secondary_id.

my models

ITEMS belongs_to :attribute belongs_to :attribute, :foreign_key => 'attribute_secondary_id' (won't work)

ATTRIBUTES has_many :items

i want to do something like the following

item.attribute.name (for primary attribute) item.attribute_secondary_id.name (not working...how should i do this?)

i don't really want to set up another table ITEM_ATTRIBUTES. Is there a way to do this as i mentioned?

2

You're close, but you just need to change the first parameter so you can distinguish between the two:

belongs_to :attribute belongs_to :secondary, :foreign_key => 'attribute_secondary_id'

The you can do something like this:

item = Item.find(1) puts item.attribute puts item.secondary # uses attribute_secondary_id column to find the associated item

This should work for you (or let me know if I misunderstood the question.)

Jeff www.purpleworkshops.com www.softiesonrails.com

3

i have a 2 tables

ITEMS id name attribute_id attribute_secondary_id

ATTRIBUTES id name

what i am trying to do is have attribute_id and attribute_secondary_id both link to the ATTRIBUTES tables. At the moment attribute_id works fine but I'm not sure how i should do the attribute_secondary_id.

I gave an example of this at Creating multiple associations with the same table - Space Vatican

Fred

4

Thanks everyone! I got it working:

    belongs_to :attribute_primary, :class_name => 'Attribute', :foreign_key => 'attribute_id'     belongs_to :attribute_secondary, :class_name => 'Attribute', :foreign_key => 'attribute_secondary_id'