# Is there an AR.delete CASCADE option? **URL:** \ **Category:** Rails\ **Created:** [November 12, 2005, 12:49pm UTC](https://www.ruby-forum.com/t/is-there-an-ar-delete-cascade-option/47625 "2005-11-12T12:49:44Z")\ **Posts on this page:** 5\ **Page:** 1

**Author:** ![carl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/ee7513/32.png) [@carl](https://www.ruby-forum.com/u/carl)\ **Post date:** [November 12, 2005, 12:49pm UTC](https://www.ruby-forum.com/t/is-there-an-ar-delete-cascade-option/47625/1 "2005-11-12T12:49:44Z")

I’m trying to delete an AR model with an habtm association with another table that is enforced with foreign key rule. The query I’m running is: ``` Resume.delete_all(["found_on <= ?", date]) ``` But the delete is failing because the rows in the other table haven’t been deleted first. Is there an easy way in AR to cause this delete to cascade without having to select out the IDs of all the rows that would be affected by this delete, delete them first and then delete these rows? Thanks, Carl ---

On 11/9/05, Carl Y. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > would be affected by this delete, delete them first and then delete > these rows? > > Thanks, Assuming your database supports it, I would that if you are using a foreign key in the database and want it to cascade, then set it that way in the database, otherwise don’t use a foreign key at all. In other words all or nothing is probably the best approach. With rails I’ve started to avoid using foreign keys unless they are really needed, especially if I want the app to support all the rails supported databases. Look at the callbacks section in the ActiveRecord documentation. You can define a before\_delete callback to do the deletions (even though that callback isn’t documented it does exist). after\_find is another nice callback and it’s not listed as a callback, although it’s referred to briefly. Chris ---

Carl Y. wrote: > these rows? > > Thanks, > > Carl See the :dependent and :exclusively\_dependent options when you set up the relationships. [http://api.rubyonrails.com/classes/ActiveRecord/Associations/ClassMethods.html](http://api.rubyonrails.com/classes/ActiveRecord/Associations/ClassMethods.html) Regards, Blair ---

Thanks. In this case, things got deleted automatically when I used destroy\_all instead of delete\_all. Carl ---

One small wrinkle I noticed with using that is that with children that utilize file\_column the related files in the file system do not get purged when the db records do … this, of course, makes sense but meant I had to make use of destroy instead… Tim