Is there any way to use active record relations?

[akira-19]

I'm trying to pass an active record model instance to a resource class.
For example, the following works when users table has id, email columns.

class UserResource
  include Alba::Resource
  
  attributes :id, :email
end

user = User.create!(email: "test@example.com")
UserResouce.new(user).serialize

I would like the followings to work if User model has has_many association with Post model.

class User < ApplicationRecord
  has_many :posts
end

class Post < ApplicationRecord
  belongs_to :user

 # posts table has id, user_id, content columns.
end

class UserResource
  include Alba::Resource
  
  attributes :id, :email
  many :articles, resource: PostResource
end

class PostResource
  include Alba::Resource
  
  attributes :content
end

user = User.create!(email: "test@example.com")
user.posts.create!(content: "content1")
user.posts.create!(content: "content2")

user_with_posts = user.preload(:posts)

UserRecord.new(user_with_posts)
# => {"id": 1, "email":  "posts": [{ "content": "content1"}, { "content": "content2" }]}

Is there any way to accomplish this?
I'd like to avoid creating another User class and Post class.
Thanks.

[okuramasafumi]

@akira-19 I think your code should work out of the box. Please let me know what error occurred if you try.

[akira-19]

@okuramasafumi Sorry, I found some mistakes in my code. It works!
I have one more question. Can I select properties in has_many association dynamically?

class UserResource
  include Alba::Resource
  
  attributes :id, :email
  many :posts, resource: PostResource
end

class PostResource
  include Alba::Resource
  
  attributes :id, :content
end

UserRecord.new(user, params: {posts: [:content]})
# => hope it returns {"id": 1, "email": "test@example.com", "posts": [{ "content": "content1"}, { "content": "content2" }]}

[okuramasafumi]

@akira-19 You can do so by splitting attributes into mandatory ones and optional ones and using if option.

class UserResource
  include Alba::Resource
  
  attributes :id, :email
  many :posts, resource: PostResource
end

class PostResource
  include Alba::Resource
  
  attributes :id, if: { params.dig(:posts, :include_id) != false }
  attributes :content
end

UserResource.new(user, params: {posts: {include_id: false})

Could you try this approach and see how it goes?

[akira-19]

@okuramasafumi Thank you. It works well! In this case, if I want to add multiple optional attributes, I have to add like followings, right?

attributes :id, if: { params.dig(:posts, :include_id) != false }
attributes :name, if: { params.dig(:posts, :include_name) != false }

[akira-19]

class PostResource
  include Alba::Resource
  
  attributes :id, :content

  def attributes
    super.select { |key, _| params.dig(:decks, :keys).include?(key) }
  end
end

UserResource.new(user, params: { posts: { keys: [:id, :content] }}).serialize

This also works. Thanks.