# Create 2 fk referencing the same table **URL:** \ **Category:** Rails\ **Created:** [June 9, 2007, 11:43am UTC](https://www.ruby-forum.com/t/create-2-fk-referencing-the-same-table/106379 "2007-06-09T11:43:32Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 9, 2007, 11:43am UTC](https://www.ruby-forum.com/t/create-2-fk-referencing-the-same-table/106379/1 "2007-06-09T11:43:32Z")
Hi everyone! I have a problem with defining 2 fk referencing the same table. I have a Program table and a Team table. The Program should have an away team and a home team fk. From my understanding, “the fk column should be named after the class of the target table, converted to lowercase, with \_id appended”. But, in my case, I have 2 fk referencing the same table. How can I do this? ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 9, 2007, 12:41pm UTC](https://www.ruby-forum.com/t/create-2-fk-referencing-the-same-table/106379/2 "2007-06-09T12:41:38Z")
On 6/9/07, removed\_email\_address@domain.invalid [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Hi everyone! I have a problem with defining 2 fk referencing the same > table. I have a Program table and a Team table. The Program should > have an away team and a home team fk. From my understanding, “the fk > column should be named after the class of the target table, converted > to lowercase, with \_id appended”. But, in my case, I have 2 fk > referencing the same table. How can I do this? I think this might work, but I didn’t set up a DB or an app to test it class Program belongs\_to :team, :foreign\_key =\> “home\_team\_id” belongs\_to :team, :foreign\_key =\> “away\_team\_id” end – F. Morgan Whitney > **[Home - Blizzo](http://www.blizzo.com)** > > Insight. Culture. Passion. OUR STORY About Our Clients We recognize that our clients are the key element in our success and that we play an important part in helping build their business and brand. Whether our client is a small service business or a... ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 9, 2007, 12:56pm UTC](https://www.ruby-forum.com/t/create-2-fk-referencing-the-same-table/106379/3 "2007-06-09T12:56:42Z")
Morgan Whitney wrote the following on 09.06.2007 12:41 : > I think this might work, but I didn’t set up a DB or an app to test it > > class Program > belongs\_to :team, :foreign\_key =\> “home\_team\_id” > belongs\_to :team, :foreign\_key =\> “away\_team\_id” > end class Program belongs\_to :home\_team, :class\_name =\> :team belongs\_to :away\_team, :class\_name =\> :team end To avoid mistakes, just remember that belongs\_to creates the: model., model.=, … accessors so you obviously don’t want several “belongs\_to …” with identical values of . (Note that this memento is mostly valid for other kinds of associations) The foreign key should be computed automatically (by adding \_id in this example), if it doesn’t suits you, then you can use the :foreign\_key parameter. See ActiveRecord docs for more. Lionel. ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 9, 2007, 12:57pm UTC](https://www.ruby-forum.com/t/create-2-fk-referencing-the-same-table/106379/4 "2007-06-09T12:57:42Z")
Lionel B. wrote the following on 09.06.2007 12:55 : > > > referencing the same table. How can I do this? > > class Program > belongs\_to :home\_team, :class\_name =\> :team better be :class\_name =\> “Team” ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 9, 2007, 1:28pm UTC](https://www.ruby-forum.com/t/create-2-fk-referencing-the-same-table/106379/5 "2007-06-09T13:28:48Z")
Thanks guys… I will try it out and get back to you… On Jun 9, 1:56 pm, Lionel B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 9, 2007, 9:51pm UTC](https://www.ruby-forum.com/t/create-2-fk-referencing-the-same-table/106379/6 "2007-06-09T21:51:43Z")
Hi, guys! I’m back…Thanks for your feedback…it worked …great advices from all of you… On Jun 9, 8:28 pm, Josh S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![casper\_the\_ghost](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/58956e/32.png) [@casper\_the\_ghost](https://www.ruby-forum.com/u/casper_the_ghost)\ **Post date:** [June 9, 2007, 7:28pm UTC](https://www.ruby-forum.com/t/create-2-fk-referencing-the-same-table/106379/7 "2007-06-09T19:28:56Z")
removed\_email\_address@domain.invalid wrote: > Hi everyone! I have a problem with defining 2 fk referencing the same > table. I have a Program table and a Team table. The Program should > have an away team and a home team fk. From my understanding, “the fk > column should be named after the class of the target table, converted > to lowercase, with \_id appended”. But, in my case, I have 2 fk > referencing the same table. How can I do this? For non-standard association names, you have to specify both the foreign key and the class name. Try this: class Program belongs\_to :home\_team, :class\_name =\> “Team”, :foreign\_key =\> “home\_team\_id” belongs\_to :away\_team, :class\_name =\> “Team”, :foreign\_key =\> “away\_team\_id” end class Team has\_many :home\_programs, :class\_name =\> “Program”, :foreign\_key =\> “home\_team\_id” has\_many :away\_programs, :class\_name =\> “Program”, :foreign\_key =\> “away\_team\_id” end – Josh S. [http://blog.hasmanythrough.com](http://blog.hasmanythrough.com)