has_and_belongs_to_many, avoiding dupes in the join table

Question

I have a pretty simple HABTM set of models

class Tag < ActiveRecord::Base 
   has_and_belongs_to_many :posts
end 

class Post < ActiveRecord::Base 
           


        

Answer 1

This is really old but I thought I'd share my way of doing this.

class Tag < ActiveRecord::Base 
    has_and_belongs_to_many :posts
end 

class Post < ActiveRecord::Base 
    has_and_belongs_to_many :tags
end

In the code where I need to add tags to a post, I do something like:

new_tag = Tag.find_by(name: 'cool')
post.tag_ids = (post.tag_ids + [new_tag.id]).uniq

This has the effect of automatically adding/removing tags as necessary or doing nothing if that's the case.