Comments on: Has Many Through Association

By: Nitish

Nitish — Fri, 12 Sep 2008 11:57:02 +0000

Hi, Can you please post an example of how I can create a User, a Newsletter and a Subscription all at the same time?
Is it needed to have a Subscriptions controller for this?

Thanks,
Nitish

By: Poli

Poli — Wed, 26 Dec 2007 18:00:26 +0000

Hello, I want to know if that is good for my aplicattion, I have three tables in mysql;
the first is Person, the second is Friend, and the third is persons_friends

These tables has :
has_and_belong_to_many for relationship

Then, I have a fourth table that is related with persons_friends;
I don’t know how to do a relationship between the fourth table and persons_friends

Poli

By: flip’s » has_and_belongs_to_many-Beziehung (habtm) mit zusätzlichen Attributen

Sun, 19 Aug 2007 10:14:02 +0000

[...] Die habtm-Funktionalität in Rails ist für n:m-Beziehungen gedacht. Was aber, wenn jede dieser Beziehungen zusätzliche Attribute mit sich bringen soll? Beispiel: ein User soll Teil verschiedener Gruppen sein können und einer Gruppe sollen mehrere User angehören können. Um dies umzusetzen, ist die habtm-Beziehung perfekt. Nun soll aber zusätzlich jeder User einer Gruppe eine Rolle inne habe, z.B. User 1 hat in Gruppe 1 die Rolle “admin”, in Gruppe 2 “member” etc. Hierfür bietet sich sich eine “has_many through” an. Weiteres unter http://www.infused.org/2005/12/06/has-many-through-association/ [...]

By: CindiDevBlog » Blog Archive » additional fields in habtm-relations

CindiDevBlog » Blog Archive » additional fields in habtm-relations — Mon, 18 Sep 2006 15:16:37 +0000

[...] Links zum Thema: rubyonrails.com::wiki::ThroughAssociations matthewman.net/…/activerecord-goes-through api.rubyonrails.org/…/ActiveRecord/…/ClassMethods wiki.rubyonrails.org/…/PolymorphicAssociations infused.org/…/has-many-through-association gmane.comp.lang.ruby.rails blog.hasmanythrough.com/…/associations blog.hasmanythrough.com/../many-to-many-dance-off wiki.rubyonrails.org/…/Beginner+Howto+on+has_many+through [...]

By: Mike at SEOG.net

Mike at SEOG.net — Fri, 21 Jul 2006 19:14:21 +0000

What is helpful about it is the additional aspects you can add when you flush out the model like that. You can say when a subscription was created, who created it, and so forth. By making the model of subscriptions it is easier to add functionality that is often wanted by marketing and business folks. Although he was talking about cases where the subscription model wasn’t defined, where it was simply a many to many relationship. Joining things with the has many :through and creating a new model allows one to stay “CRUD”-y and the benefits that comes along with that.

By: BeepHONK rumbles to life… at 72mach1.com

BeepHONK rumbles to life… at 72mach1.com — Thu, 13 Apr 2006 02:52:41 +0000

[...] I’ve got most of the initial featureset roughed in. It’s even got some sprinklings of AJAX and DOM JavaScript effects. I’ve got a problem with the :through relationships that came about somewhere between the 1.0 and 1.1 release of Rails. Never fear though I’ll get it working soon enough. [...]

By: Edoardo "Dado" Marcora

Edoardo "Dado" Marcora — Tue, 14 Mar 2006 08:46:26 +0000

I also need it for a self-referential many-to-many relationship and I also can’t get it to work.

By: Randy Schmidt

Randy Schmidt — Tue, 28 Feb 2006 05:17:03 +0000

I think I really need this for a site I’m working on, however, I need it for a self-referential many-to-many relationship and I have had no luck getting it to work. Does anybody know how I could make this work?

By: Peter Morris

Peter Morris — Sat, 31 Dec 2005 08:30:19 +0000

Hmmm, the original code, before the “through” could be re-written like……

@users = User.find :all, :conditions => “name like ‘k%’�?
@users.each {|u| u.subscriptions.each{|s| s.mail(u.email,s.email_format)}}

you could even get rid of @users and have the .each hanging off of the find.

You COULD do sommat like….

@users = find … blah blah …
@users.collect{|u| u.subscriptions.collect{|s| [u, s]}}.each{|t| t[1].mail(t[0].email, t[1].email_format)}

But it would be a bad idea, as you would be building an in-memory array with as many rows as you have subscriptions whos subscribers name begins with ‘k’.

By: Simon Harris

Simon Harris — Sun, 25 Dec 2005 23:04:17 +0000

Excellent. I look forward to it.

Cheers,

Simon

P.S. Apologies for the unformatted code. It was late and I didn’t notice the list of allowable tags below :)