# Foreign keys and migrations **URL:** \ **Category:** Rails\ **Created:** [April 2, 2006, 4:02am UTC](https://www.ruby-forum.com/t/foreign-keys-and-migrations/56645 "2006-04-02T04:02:29Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![esquilax](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/e0b2c6/32.png) [@esquilax](https://www.ruby-forum.com/u/esquilax)\ **Post date:** [April 2, 2006, 4:02am UTC](https://www.ruby-forum.com/t/foreign-keys-and-migrations/56645/1 "2006-04-02T04:02:29Z")
Hi: I’m looking to get a point clarified which i’m sure is obvious to everyone else but I haven’t been able to find the answer to. i’ve tried searching through the forums and the api pages and haven’t found anything. Is there a way with migrations to set up foregin key relationships? (beyond putting in the relevant foregin\_id attributes) Is that just supposed to be handeled at the model level with “belongs\_to” and “has\_many” .etc… ? I guess what I’m asking is whether relationships should just be handeled at the business level or at the business level and data level? Is there a best practices issue at work here? lots of questions I know but I’m trying hard to learn:) thanks! Andrew ---
**Author:** ![esquilax](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/e0b2c6/32.png) [@esquilax](https://www.ruby-forum.com/u/esquilax)\ **Post date:** [April 2, 2006, 6:05am UTC](https://www.ruby-forum.com/t/foreign-keys-and-migrations/56645/2 "2006-04-02T06:05:51Z")
On Sun, 2006-04-02 at 04:02 +0200, Andrew G. wrote: > Is that just supposed to be handeled at the model level with > “belongs\_to” and “has\_many” .etc… ? > > I guess what I’m asking is whether relationships should just be handeled > at the business level or at the business level and data level? Is there > a best practices issue at work here? > > lots of questions I know but I’m trying hard to learn:) * * * assuming that rails 1.1 didn’t change these things (and I didn’t notice an indication that it did change), I have them added at the bottom of the appropriate migration file in raw sql form… just before the ‘end’ tag for def self.up… ``` # set up foreign key restratints for PostgreSQL execute 'ALTER TABLE ONLY clients ADD CONSTRAINT fk_cp_case_manager ``` FOREIGN KEY (case\_manager\_id) REFERENCES case\_managers(id);’ etc. (note that my mail client will cause this to wrap on 2 lines but I don’t know that is significant). Craig ---
**Author:** ![esquilax](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/e0b2c6/32.png) [@esquilax](https://www.ruby-forum.com/u/esquilax)\ **Post date:** [April 2, 2006, 3:16pm UTC](https://www.ruby-forum.com/t/foreign-keys-and-migrations/56645/3 "2006-04-02T15:16:13Z")
Craig W. wrote: > ``` > execute 'ALTER TABLE ONLY clients ADD CONSTRAINT fk_cp_case_manager > > ``` > > FOREIGN KEY (case\_manager\_id) REFERENCES case\_managers(id);’ Do you need to set up foreign keys. I did not, and everything seems to be working… ---
**Author:** ![esquilax](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/e0b2c6/32.png) [@esquilax](https://www.ruby-forum.com/u/esquilax)\ **Post date:** [April 2, 2006, 5:25pm UTC](https://www.ruby-forum.com/t/foreign-keys-and-migrations/56645/4 "2006-04-02T17:25:57Z")
On Sun, 2006-04-02 at 15:16 +0200, oom tuinstoel wrote: > Craig W. wrote: > > > ``` > > execute 'ALTER TABLE ONLY clients ADD CONSTRAINT fk_cp_case_manager > > > > ``` > > > > FOREIGN KEY (case\_manager\_id) REFERENCES case\_managers(id);’ > > Do you need to set up foreign keys. I did not, and everything seems to > be working… * * * No - rails obtains the information from the models. This is for PostgreSQL - i.e. if you are using the tables with other client applications. Craig ---
**Author:** ![esquilax](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/e0b2c6/32.png) [@esquilax](https://www.ruby-forum.com/u/esquilax)\ **Post date:** [April 2, 2006, 7:10pm UTC](https://www.ruby-forum.com/t/foreign-keys-and-migrations/56645/5 "2006-04-02T19:10:52Z")
subversion is your friend (version control) svn revert Craig ---
**Author:** ![esquilax](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/e0b2c6/32.png) [@esquilax](https://www.ruby-forum.com/u/esquilax)\ **Post date:** [April 2, 2006, 6:58pm UTC](https://www.ruby-forum.com/t/foreign-keys-and-migrations/56645/6 "2006-04-02T18:58:23Z")
On a slight aside, one thing that would be nice is if you could migrate the models along with the database. If I have to skip back to a different version of my database for any reason, I find myself having to comment out and change parts of my model to prevent it from going all wrong. -Nathan