# Relationships on a non ID field **URL:** \ **Category:** Rails\ **Created:** [August 10, 2009, 2:35pm UTC](https://www.ruby-forum.com/t/relationships-on-a-non-id-field/173492 "2009-08-10T14:35:25Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![pmckinstry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/f6c823/32.png) [@pmckinstry](https://www.ruby-forum.com/u/pmckinstry)\ **Post date:** [August 10, 2009, 2:35pm UTC](https://www.ruby-forum.com/t/relationships-on-a-non-id-field/173492/1 "2009-08-10T14:35:25Z")
Hi Guys, I am a total newbie to rails - so please go easy 🙂 So I have 2 models Country and City - the Country Model will have a ‘name’ and a ‘code’ field (so a record would be ID name code 1 United Kingdom UK Then my City table would look something like ID country\_code city\_code name 2 UK LON London So I guess the question is can you use has\_many :city which would form the relationship based on the char code rather than a ID? Regards ---
**Author:** ![pmckinstry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/f6c823/32.png) [@pmckinstry](https://www.ruby-forum.com/u/pmckinstry)\ **Post date:** [August 10, 2009, 2:52pm UTC](https://www.ruby-forum.com/t/relationships-on-a-non-id-field/173492/2 "2009-08-10T14:52:03Z")
On Aug 10, 1:35 pm, Pete M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Then my City table would look something like > > ID country\_code city\_code name > 2 UK LON London > > So I guess the question is can you use has\_many :city which would form > the relationship based on the char code rather than a ID? has\_many does have a primary\_key option for this sort of thing. I would more commonly have a country\_id column on cities rather than a country\_code column Fred ---
**Author:** ![pmckinstry](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/f6c823/32.png) [@pmckinstry](https://www.ruby-forum.com/u/pmckinstry)\ **Post date:** [August 10, 2009, 2:54pm UTC](https://www.ruby-forum.com/t/relationships-on-a-non-id-field/173492/3 "2009-08-10T14:54:02Z")
Pete M. wrote: > So I have 2 models Country and City - the Country Model will have a > ‘name’ and a ‘code’ field (so a record would be > > ID name code > 1 United Kingdom UK > > Then my City table would look something like > > ID country\_code city\_code name > 2 UK LON London Country ID name code 1 United Kingdom UK City ID country\_id city\_code name 2 1 LON London Country has\_many :cities City belongs\_to :country