# Are there RESTful verbs for association actions?

**URL:** <https://www.ruby-forum.com/t/are-there-restful-verbs-for-association-actions/80868>\
**Category:** Rails\
**Created:** [December 31, 2006, 7:59pm UTC](https://www.ruby-forum.com/t/are-there-restful-verbs-for-association-actions/80868 "2006-12-31T19:59:15Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jose](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e274bd/32.png) [@jose](https://www.ruby-forum.com/u/jose)\
**Post date:** [December 31, 2006, 7:59pm UTC](https://www.ruby-forum.com/t/are-there-restful-verbs-for-association-actions/80868/1 "2006-12-31T19:59:15Z")

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I’m familiar with CRUD and the mapping of the four actions (create,  
read, update, delete) to the four SQL statements (insert, select,  
update, destroy).

I have other actions dealing with associations. For example, I want  
to remove a book from a list. In this case I’m not deleting  
(destroying) the book record but removing its association from a  
list. The controller method’s code would look like…

def remove  
@list = List.find(params[:id])  
@list.books.delete(Book.find(params[:book]))  
redirect\_to :action =\> ‘edit’, :id =\> @list  
end

Although the association method is delete. I don’t the user thinking  
they are deleting the book, and want to convey to them instead that  
they are removing the book from the list.

I can think of these association related actions:

Remove - remove a record from a list.  
Add - to add a record to a list.

Is there a consensus on action names for association related  
manipulations?

Jose

…  
Jose Hales-Garcia  
UCLA Department of Statistics  
removed\_email\_address@domain.invalid

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<div class="post-metadata">

**Author:** ![jose](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e274bd/32.png) [@jose](https://www.ruby-forum.com/u/jose)\
**Post date:** [December 31, 2006, 8:29pm UTC](https://www.ruby-forum.com/t/are-there-restful-verbs-for-association-actions/80868/2 "2006-12-31T20:29:22Z")

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Jose Hales-Garcia wrote:

> I have other actions dealing with associations. For example, I want to  
> remove a book from a list.

In this specific case you need to read up on has\_many :through. It  
solves this problem nicely by having the relationship represented as a  
real model instead of an anonymously. So in this case you may have  
another model called “ListMembership”. When you add a book to the list  
you create on the ListMembership model. When you delete a book from the  
list you delete on the ListMembership model. This allow you to move back  
to all your actions being CRUD.

But on the more general level not all actions can be reduced to CRUD by  
simply introducing more models. Sometimes you really need different  
actions. In these cases you just need to realized that you need to break  
out of CRUD (it is just a design pattern and doesn’t have to be  
religiously followed) and move to having actions that are not CRUDdy.

Eric

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<div class="post-metadata">

**Author:** ![jose](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/e274bd/32.png) [@jose](https://www.ruby-forum.com/u/jose)\
**Post date:** [December 31, 2006, 8:37pm UTC](https://www.ruby-forum.com/t/are-there-restful-verbs-for-association-actions/80868/3 "2006-12-31T20:37:25Z")

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Hi –

On Sun, 31 Dec 2006, Jose Hales-Garcia wrote:

> ```
> @list = List.find(params[:id])
> 
> ```
> 
> Remove - remove a record from a list.  
> Add - to add a record to a list.
> 
> Is there a consensus on action names for association related manipulations?

Not a universal consensus. I’d say there are different takes on best  
or reasonable practice. One is to use ad hoc method names based on  
what’s happening, like lists/add\_book. I don’t think that’s so  
horrible, but it definitely lies outside any kind of CRUD and/or  
RESTful convention and therefore won’t garner you any of the possible  
advantages of those conventions.

With CRUD edge cases generally, one thing you can do is force the  
issue by asking: “If I _were_ performing a CRUD operation, what would  
it be? And on what entity or resource would I be performing it?”  
Here, the answer is that you would be deleting (destroying) a Listing  
– not a List or a Book, as you point out, but an instance of the  
connectedness _between_ a list and a book.

So… you could have a listings controller, and in it you would do  
(refined as needed):

def create  
list = List.find(params[:list\_id])  
book = Book.find(params[:book\_id])  
list.books \<\< book  
end

def destroy  
# ditto, but remove  
end

There’s a second stage to the process, if you want to do it, and that  
is to also have a Listing model. If you feel it unnecessarily  
complicates your associations to do it that way (it would generally  
entail a has\_many :through association), there’s no overriding reason  
to do it. You can still have a listings controller (and I’ve actually  
been finding modelless controllers increasingly useful and RESTful).  
But the Listing model is another potential aspect of thinking of the  
listing itself as something that your application addresses, not  
through book or list but alongside them.

David

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