Linking a class to itself

Rails
1

I have a few classes. One of them, articles, can have other articles
linked to it. Is the best way to model this with a
belongs_to_and_has_many, ie

class Article
belongs_to_and_has_many :articles
…
end

So i can then say (eg in a list view)

for article in @article.articles
#do something with article
end

Will this work?

Assuming this is the best way to do it, in the join table, which will be
called articles_articles, i’m going to have to rename one or both of the
columns from the default of article_id (since i can’t have two fields
ith the same name). How do i tell rails the new column names?

Appreciate any advice…

2

Max W. wrote:

Assuming this is the best way to do it, in the join table, which will be
called articles_articles, i’m going to have to rename one or both of the
columns from the default of article_id (since i can’t have two fields
ith the same name). How do i tell rails the new column names?

Appreciate any advice…

I did something like this for old application (done twice to make it two
way):

class Company
has_and_belongs_to_many :corporate_shares_held_in,
:class_name => ‘Company’,
:join_table => ‘company_share_holders’,
:foreign_key => ‘company_id’,
:association_foreign_key => ‘share_holder_company_id’

has_and_belongs_to_many :corporate_share_holders,
:class_name => ‘Company’,
:join_table => ‘company_share_holders’,
:foreign_key => ‘share_holder_company_id’,
:association_foreign_key => ‘company_id’
end

You should be able to use has_many :through though - try searching
google “self referential has_many through”.

Cheers
Luke

3

class Company
has_and_belongs_to_many :corporate_shares_held_in,
:class_name => ‘Company’,
:join_table => ‘company_share_holders’,
:foreign_key => ‘company_id’,
:association_foreign_key => ‘share_holder_company_id’

Thanks - i actually just did something very similar and it worked - i
set up join a table called article_links, where links are articles as
well. Then, like you say above:

has_and_belongs_to_many :links,
:class_name => “Article”,
:association_foreign_key => “link_id”,
:join_table => “articles_links”

Seems to work great, and it’s much nicer talking about “link in
@article.links” than “article in @article.articles” which would have
been confusing :slight_smile:

cheers!

4

Max, I have the same situation and model it like this:

class Article…
has_and_belongs_to_many :related_articles,
:class_name => “Article”,
:join_table => “related_articles”,
:association_foreign_key => “related_article_id”,
:foreign_key => “article_id”

The related_articles table just has article_id and related_article_id
(no id column required)

Regards,

–Kip

On Jul 26, 12:22 am, Max W. [email protected]