# Foreign key on the same table testing **URL:** \ **Category:** Rails\ **Created:** [November 13, 2007, 11:51am UTC](https://www.ruby-forum.com/t/foreign-key-on-the-same-table-testing/120050 "2007-11-13T11:51:21Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![pascalschudel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/5f8ce5/32.png) [@pascalschudel](https://www.ruby-forum.com/u/pascalschudel)\ **Post date:** [November 13, 2007, 11:51am UTC](https://www.ruby-forum.com/t/foreign-key-on-the-same-table-testing/120050/1 "2007-11-13T11:51:21Z")
Hi @all I wrote a rails app and now I want to test it. For this, I’d like to use test fixtures wich I created in .yml-files. In my model, each object can include another object. This is done by a foreign key. Unfortunately, there is always an error becaus of a foreign key constraint which fails. Does anybody knows how to solve this problem? My .yml-file looks like this: one: id: 1 person\_id: 1 father: null person\_type: parent two: id: 2 person\_id: 2 father: 1 person\_type: child If I only insert the first one, it works… Thanks for your help! ---
**Author:** ![pascalschudel](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/5f8ce5/32.png) [@pascalschudel](https://www.ruby-forum.com/u/pascalschudel)\ **Post date:** [November 13, 2007, 1:56pm UTC](https://www.ruby-forum.com/t/foreign-key-on-the-same-table-testing/120050/2 "2007-11-13T13:56:38Z")
On Nov 13, 2:51 am, Pa Sc [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > one: > If I only insert the first one, it works… > > ## Thanks for your help! > > Posted viahttp://www.ruby-forum.com/. it isn’t clear if your’e doing single table inheritance (STI) or a acts\_as\_nested\_set (or acts\_as\_tree) structure, but these are both well-established techniques with constraints on column names, if you do a search for them