Comments on: has_many :through Self-referential Example

By: Sunil

Sunil — Wed, 17 Jun 2009 06:49:24 +0000

Hi ,
I wanted to know how i can set “authorized” field to true.. Actually what I am doing is, current user can add another user as friend(which will send him a friendship request).
Now, when he clicks on Add user or allow user I want to set authorized to true. But since there is no id field in the table, I can neither say update_attribute nor can i call save! method.
Thanks for any help
Sunil

By: anonymous

anonymous — Wed, 25 Feb 2009 17:09:32 +0000

Very nice article.

Anyone have any suggestions getting this to work when both the friendships table and the persons table are using STI?

I have been trying but keep on getting AsociationTypeMismatch errors.

By: Giorgio

Giorgio — Sat, 31 Jan 2009 01:14:01 +0000

You made my day John.
:)

And also very well commented.

Thanks

By: Daniel

Daniel — Wed, 04 Jun 2008 17:59:40 +0000

this was helpful. particularly the comment in the example source:

# tell ActiveRecord that a person has_many friendships or :through won’t work

thanks!

By: John Ford

John Ford — Tue, 22 Apr 2008 17:39:44 +0000

art, Are you using destroy or delete? Remember, in rails that delete just deletes the record from the database but destroy will call the correct callbacks to destroy associated objects.

By: art

art — Tue, 22 Apr 2008 06:07:13 +0000

When removing a friend, would you have to manually remove the friendship as well as the friend?

current_user.friends.delete(unwanted_friend)

and

unwanted_relationship = current_user.relationships.find_by_friend_id…
current_user.relationships.delete(unwanted_relationship)

By: Mike McKinney

Mike McKinney — Fri, 15 Feb 2008 18:45:58 +0000

Just wanted to thank you for this post… it really helped me out today.

By: John Ford

John Ford — Tue, 29 Jan 2008 19:17:07 +0000

Rails won’t be able to tell what table to use in that case without giving the source. Here’s what the documentation has to say about has_many source:

:source: Specifies the source association name used by has_many :through queries. Only use it if the name cannot be inferred from the association. has_many :subscribers, :through => :subscriptions will look for either :subscribers or :subscriber on Subscription, unless a :source is given.

By: Todd

Todd — Fri, 25 Jan 2008 18:18:21 +0000

Nice example. Quick question:

# create the has_many :through relationship
has_many :friends, :through => :friendships

# an example of how to get only the authorized friends
has_many :authorized_friends, :through => :friendships,
:source => :friend, :conditions => [ "authorized = ?", true ]

Why do you need :source in :authorized_friends but not in :frinds?

By: John Ford

John Ford — Fri, 18 May 2007 00:57:29 +0000

Nick, it should work fine since @user.friends will make an SQL call that says “user_id = ?” making sure only friends associated with that user_id are found.

If you’ve befriended yourself then you might get back your own user object… which is your best friend… or something.