Support for specifying context

[mattandayo]

Hello,
Thank you for providing the excellent gem 👍
I am considering adopting Alba for my Rails project.

I would like to change the serializer specification depending on the context.
I tried to achieve it using the functionality of params as shown below, but after reading the source code, I confirmed that the block that is passed to the resource is not possible to receive params.

class User
  attr_reader :posts

  def initialize(posts)
    @posts = posts
  end
end

class Post
  attr_reader :id, :token, :title

  def initialize(id, token, title)
    @id = id
    @token = token
    @title = title
  end
end

class UserSerializer
  include Alba::Resource

  many :posts, serializer: proc { |object, params|
    case params[:context]
    when 'consumer' then Consumers::PostSerializer
    when 'provider' then Providers::PostSerializer
    end
  }
end


module Consumers
  class PostSerializer
    include Alba::Resource

    root_key!

    attributes :title

    attribute :id, &:token
  end
end

module Providers
  class PostSerializer
    include Alba::Resource

    root_key!

    attributes :id, :token
  end
end

module Consumers
  class UsersController < ApplicationController
    def show
      render json: UserSerializer.new(User.new(1, SecureRandom.alphanumeric, 'Alba is great!'), params: { context: 'consumer' })
      # => { "user": { posts: [{ "id": "abcd...", "title": "Alba is great!"}, ...] }}
    end
  end
end

module Providers
  class UsersController < ApplicationController
    def show
      render json: UserSerializer.new(User.new(1, SecureRandom.alphanumeric, 'Alba is great!'), params: { context: 'provider' })
      # => { "user": { posts: [{ "id": 1, "title": "Alba is great!"}, ...] }}
    end
  end
end

I can think of a way to achieve it without using the params by adding an interface like context to the object, but I don't think it's very elegant.

It would be great if I could specify the context as follows, but do you have any plans to implement it in future versions?

class UserSerializer
  include Alba::Resource

  many :posts, serializer: proc {
    case context
    when 'consumer' then Consumers::PostSerializer
    when 'provider' then Providers::PostSerializer
    end
  }
end

module Consumers
  class ApplicationController
    before_action do
      Alaba.context = 'consumer'
    end
  end

  class UsersController < ApplicationController
    def show
      render json: UserSerializer.new(User.new(1, SecureRandom.alphanumeric, 'Alba is great!'))
      # => { "user": { posts: [{ "id": "abcd...", "title": "Alba is great!"}, ...] }}
    end
  end
end

module Providers
  class ApplicationController
    before_action do
      Alaba.context = 'provider'
    end
  end

  class UsersController < ApplicationController
    def show
      render json: UserSerializer.new(User.new(1, SecureRandom.alphanumeric, 'Alba is great!'))
      # => { "user": { posts: [{ "id": 1, "title": "Alba is great!"}, ...] }}
    end
  end
end

[okuramasafumi]

@mattandayo Hi, thank you for the suggestion.
The idea of context is interesting, but there seem to be some problems.

1. Where does it belong? One context might belongs to only one resource or be shared with multiple resources.
2. What is the default value? In the case you provided, if we forget to assign context it causes a weird behavior. We can set the default value in else clause but it's not easy to find

Instead of introducing context, I'd like to modify params accessible in serializer proc. If it's not enough let's discuss it again.