Hi everyone. I'm trying to figure out how to implement site-wide tagging for my website. I have a rails-based weblog that supports tagging posts. There's a has_and_belongs_to_many relationship between posts and tags. I'd like to now reuse those tags for tagging links as well. Where I have a posts_tags table with post_id and tag_id fields, I'd like to add a link_id field. I'd like to use just one table so that I can easily pull all posts and links associated with a given tag. If I make a has_and_belongs_to_many relationship between tags and links I seem to need a links_tags table. How do I make the links/tags relationship appear in the same table as the posts/tags relationship? Thank you for the help. -Jeff
on 2006-06-04 08:00
on 2006-06-04 11:34
Well, has_many :through sounds like what you need. In order to put more than just two fields in a many-to-many table, you use has_many :through. class Posts < ActiveRecord::Base has_many :post_tags has_many :tags, :through => post_tags end class Links < ActiveRecord::Base has_many :post_tags has_many :tags, :through => post_tags end class PostTags < ActiveRecord::Base belongs_to :posts belongs_to :links belongs_to :tags end If I were you, I'd make two join tables rather than trying to put it all into one. It'll be no more difficult to search by tags, I reckon. Think of all the null attributes you'll have in your post_tags table. That'll make things difficult. Hope this helps, -Nathan
on 2006-06-04 18:29
Great. Thanks for the suggestion.