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

In addition the suggestions above:

1. add :uniq to the has_and_belongs_to_many association
2. adding unique index on the join table

I would do an explicit check to determine if the relationship already exists. For instance:

post = Post.find(1)
tag = Tag.find(2)
post.tags << tag unless post.tags.include?(tag)