Class: Shrine::Plugins::KithePromotionCallbacks

Inherits:
Object
  • Object
show all
Defined in:
lib/shrine/plugins/kithe_promotion_callbacks.rb

Overview

We want ActiveSupport-style callbacks around “promotion” – the shrine process of finalizing a file by moving it from ‘cache’ storage to ‘store’ storage.

We want to suport after_promotion hooks, and before_promotion hooks, the before_promotion hooks should be able to cancel promotion. (A convenient way to do validation even with backgrounding promotion, although you’d want to record the validation fail somewhere)

For now, the actual hooks are registered in the ‘Asset` activerecord model. This works because our Asset model only has ONE shrine attachment, it is backwards compatible with kithe 1. It might make more sense to have the callbacks on the Uploader itself, in the future though.

We want to be able to register these callbacks, and have them invoked regardless of how promotion happens – inline; in a background job; or even explicitly calling Asset#promote

## Weird implementation

It’s a bit hard to get this to happen in shrine architecture. We end up needing to assume activerecord and wrap the activerecord_after_save method (for inline promotion). And then also overwrite atomic_promote to get background promotion and other cases.

Because getting this right required some shuffling around of where the wrapping happened, it was convenient and avoided confusion to isolate wrapping in a class method that can be used anywhere, and only depends on args passed in, no implicit state anywhere.

Defined Under Namespace

Modules: AttacherMethods

Class Method Summary collapse

Class Method Details

.load_dependencies(uploader) ⇒ Object 



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# File 'lib/shrine/plugins/kithe_promotion_callbacks.rb', line 27

def self.load_dependencies(uploader, *)
  uploader.plugin :kithe_promotion_directives
end

.with_promotion_callbacks(model) ⇒ Object

promotion logic differs somewhat in different modes of use (bg or inline promotion), so we extract the wrapping logic here. Exactly what the logic wrapped is can differ.

Kithe::PromotionCallbacks.with_promotion_callbacks(record) do
   promotion_logic # sometimes `super`
end



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# File 'lib/shrine/plugins/kithe_promotion_callbacks.rb', line 39

def self.with_promotion_callbacks(model)
  # If callbacks haven't been skipped, and we have a model that implements
  # callbacks, wrap yield in callbacks.
  #
  # Otherwise, just do it.
  if (  !model.file_attacher.promotion_directives["skip_callbacks"] &&
        model &&
        model.class.respond_to?(:_promotion_callbacks) )
    model.run_callbacks(:promotion) do
      yield
    end
  else
    yield
  end
end