DynamoDB Dynomite Belongs To

Important: These docs are for the outdated Jets 5 versions and below. For the latest Jets docs: docs.rubyonjets.com

Example:

app/models/post.rb

class Post < ApplicationItem
  belongs_to :user
end

There is typically a corresponding has_many as the inverse relationship.

app/models/user.rb

class User < ApplicationItem
  has_many :posts
end

Creating

user = User.find("bob")
Post.find("post-1").user = user
Post.find("post-2").user = user

This will store the ids in the users.posts_ids field as a String Set and in the posts.user_id field as a String.

user.posts_ids # <Set: {"post-1"}>
Post.find("post-1").user_id # "bob"
Post.find("post-2").user_id # "bob"

Deleting

There’s no delete method on a single association like belongs_to. This is because the post.user returns a User model instance. If you delete the like so:

post = Post.find("post-1")
post.user.delete # you're deleting the User!

Instead, you disassociate by assigning the belongs_to relationship to nil.

Disassocating

Post.find("post-1").user = nil
Post.find("post-2").user = nil

This will disassociate both sides of the relationship if both have been set up.

Post.find("post-1").user    # nil
Post.find("post-2").user    # nil
User.find("bob").posts_ids  # nil