# Self refrencing many to one implementation **URL:** \ **Category:** Rails\ **Created:** [February 21, 2010, 10:53am UTC](https://www.ruby-forum.com/t/self-refrencing-many-to-one-implementation/183831 "2010-02-21T10:53:24Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![mac](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/cc9497/32.png) [@mac](https://www.ruby-forum.com/u/mac)\ **Post date:** [February 21, 2010, 10:53am UTC](https://www.ruby-forum.com/t/self-refrencing-many-to-one-implementation/183831/1 "2010-02-21T10:53:24Z")
hello, i have database for dynamic website in which i need to store information about each menu and its relationship with other menu. it is obvious that each menu can have several submenu but each submenu must belong to one and ony one menu. so database goes like this Pk\_Content\_id=\>integer title =\>integer, it is name of menu Image\_path=\>string, path of image Content\_text=\> text contained on click of every menu or description fK\_parent\_content\_id =\> integer , THIS LINKS BACK TO pk\_content\_id ,as is a foreign key what i want is to relate pk\_content\_id and fk\_parent\_content\_id (which are in same table) how to accomplish such self refrencing many to one relation??? m extreme beginner in rails please be more descriptive. just to mention pk- represents primary key so is unique while fk is foreign key and is not unique, combinaly forms one to many relation thanks in advance ---
**Author:** ![mac](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/cc9497/32.png) [@mac](https://www.ruby-forum.com/u/mac)\ **Post date:** [February 21, 2010, 11:09am UTC](https://www.ruby-forum.com/t/self-refrencing-many-to-one-implementation/183831/2 "2010-02-21T11:09:13Z")
On 21 February 2010 05:50, mac [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Pk\_Content\_id=\>integer The term you’re looking for is “self referential” - very handy when Authors have Readers, or Employees have Managers… You’ll find lots of tutorials online, but essentially you set it up thus: # Menu model has\_many :children, :class\_name =\> “Menu”, :foreign\_key =\> “parent\_content\_id” # those ‘pk/fk’ prefixes are not really good from the Rails conventions belongs\_to :parent, , :class\_name =\> “Menu” But you might find that one of the “nesting” algorithms suits your need better - seeing as it seems you might be constantly recurring down the menus, “awesome\_nested\_set” might be worth a look. Hope this helps put you on track.