CODEWITHSUNDEEP
ruby-on-railsactiverecord
Amanda Ferrari
Amanda Ferrari

Reputation: 946

How to handle entries that could need the same id

I have the following models:

class Site
  has_many :posts
end

class Post
  belongs_to :site
end

And the post has the following columns:

id
site_id
url
title
body

This is going to store wordpress posts, and I want to use the post_id of wordpress post, and because of that I could have two sites that would have the post 1 for example. So I need a way to have duplicated post ids, but pointing to different entries.

Thank you.

Upvotes: 1

Views: 32

Answers (1)

Tamer Shlash
Tamer Shlash

Reputation: 9523

Regardless of this use case, it's a bad practice to make your ActiveRecord id rely on another data source.

For your case, ignore the conventional id and store the WordPress post ID in a new column, let's call it wp_id, which is not unique across the table.

Then, you can create the following index to make queries faster and assure the uniqueness of post ID per site:

add_index :posts, [:site_id, :wp_id], unique: true

This way, you get what's called a composite key, means every combination of both site_id and wp_id is unique across the posts table.

Upvotes: 1

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