Join two models

rubyonrails-talk
1

Need some help with understanding the best way of doing the following:

I have a user model and two models (link_post and text_post) i now want to join the models together as post. both link_post and text_post has a user_id column.

What a i want is to get   u = User.first   u.posts   to collect all link_post and text_post together.

Should this be done with a scope or with some model association ? I don't need a controller for posts just the self join. But if i can get other scopes on "posts" it would be great... (like published_on etc ...)

2

Have a look at the Rails Guide on ActiveRecord Associations. That should get you started.

Colin

3

Looks like you could use inheritance here, with LinkPost and TextPost inheriting from Post. Then user would 'has_many :posts' and that way when you do:    u.posts You would get both link_posts and text_posts

Also you'll probably want to call the previous as:   User.includes(:posts).all

This way you 'preload' posts and save yourself from making an extra sql request each time you hit a user in an iteration ( for more info. google: n+1 query)

4

Thanks, got it sort of working. Would like to drop < ActiveRecord::Base from Post (don't want to create a table for Posts) just the TextPost and LinkPost, will work on that tonight. Thanks again.

/Niklas.