Support for scopes

[krainboltgreene]

I realize #scopes is a feature specific to ActiveRecord and this library is pretty agnostic. Here's an example:

class Cart
  has_many :items
end

class Item
  belongs_to :cart

  scope :nikes, -> { where(brand: "nike") }
end

cart.items.nikes

With this library it raises an error:

NoMethodError: undefined method `nikes' for #<Disposable::Twin::Collection:...>

I'm not sure how it would work, but I would love to see this:

class ItemTwin < Disposable::Twin
  property :brand
  property :cart

  subset :nikes, twin: ItemTwin
end

[apotonick]

This works, you just have to do as follows.

class Cart::Twin < Disposable::Twin
  collection :nikes, twin: ItemTwin

  def nikes
   super model.items.nikes
  end
end

[krainboltgreene]

Oooh, that's a great example, should be in the readme.

[krainboltgreene]

Actually, that doesn't work :(

Are you sure about the syntax?

[apotonick]

Never ever again say "this doesn't work" anymore in a programming context. Please.

What happens?

[apotonick]

BTW, I love your blog, you should blog more. :rocket:

[krainboltgreene]

Well first I noticed you used Cart::Twin, so I guessed you either made a typo or you're namespacing to cart. Second, you're defining the collection on either Cart or this new Cart::Twin object, the former results in ActiveRecord saying "Hey, nikes isn't a method I know about for Cart" and the second way results in the same error as the original ticket.

[apotonick]

@krainboltgreene Jump on https://gitter.im/trailblazer/chat we can figure it out there ;)

[krainboltgreene]

So in-between writing a monkey patch to add subsets for my application I realized another approach that is less than easy to understand but works:

class CartTwin
  property :items, twin: ItemCollectionTwin
end

class ItemCollectionTwin
  collection :nikes, twin: ItemTwin
end

[apotonick]

That's ingenious!

So, you basically could macro-ize that in a Scope feature model. What do you think? And that could be marked as writeable: false, as discussed in the other issue that I can't find.

[apotonick]

The Scope feature module being part of Disposable, of course! :beer:

lib/disposable/presentation/scope.rb or something...

[krainboltgreene]

See #26 #23 latest and once we finish those discussions I'll start a PR that adds this special functionality.

Which would you prefer: extension gem (disposable-activerecord or something) or directly in disposable?

[apotonick]

Sorryyyy for the delay! Let's do a disposable-orm gem, since scopes are pretty generic. We can discuss everything based on your code, then.

Does that sound good?

[krainboltgreene]

Sooooo as someone who does a lot of foss projects I hate to say this, but I think we're going to reimplement disposable's use case (soft application) in a new library internally and possibly release.

[krainboltgreene]

Meaning it might be useful to just close these issues.

[apotonick]

Oh I've heard that many times and then never seen any free OSS code based on the original stuff. Good luck!

Eager to hear your ideas, what you will change.