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General • Asked by Chris Oliver

Could you post the source code to this?

Absolutely! Just posted it here: https://github.com/excid3/g...


event.eventable is an instance of a class right

Yep! That's correct. It's actually another model instance but just given the name of "eventable" because it could be of various types of models.


Chris,
How do we handle deletion dependencies here? E.g. say I setup an event to be trigged on a `comment` creation, or when I upload an image. But what happens when I delete that comment or I delete that image. Ideally, I would like to be able to delete the event that is related to that specific recently deleted comment or image.

What's the best way to do this?

This is a fantastic question. If you setup the reverse dependency and set the dependent destroy option, that will delete the events when you delete the comment.

class Comment
has_many :events, as: :eventable, dependent: :destroy
end

Ahh perfect. So that covers most use-cases. How do I handle virtual attributes, e.g. 'votes'. So I am using acts_as_votable, which creates a bunch of virtual attributes to indicate when a user has `liked` a `Node`. When that node is deleted, all of those virtual attributes are deleted, so I would like to delete all of those events too.

Do I have to do this manually in an `after_delete :callback` on my `Node` model or is there some other way?

Depending on how that's setup, you might patch the Vote model so that if you created events matched to the vote, you could delete those. You can't really set this up on virtual attributes because you need it attached directly to the records so when things get deleted you can remove the related records.

Yeh....so I guess the solution just may be in the removal of the Node callback. Or just adding the `dependent: :destroy` on my Node model. Or maybe I just ignore it, given that it is just a like.


Love it keep it up Chris


Hey Chris. Thanks for all the awesome tutorials. If I wanted to add a link to "Unfollow" and delete the event, what would that look like?


It looks like the `lookup_context.template_exists?()` method now requires the prefixes to be an array, or an enumerable that responds to `.map()`, instead of just a string. This was changed as previous versions of Rails (< 3.1) accepted a string prefix. I'm not sure why it works in the episode, since you're using Rails 4; maybe it was a soft deprecation?

https://apidock.com/rails/ActionView/LookupContext/ViewPaths/template_exists%3f

Great video, man. I had originally figure out how to do this on my own, and was like, "that's me!" when you mentioned how not to do it. Thanks for showing an alternative to "if activity type is this, show this". I was able to refactor quite a bit of code.


I have my events set up. Some of the models I have are listings and reviews. Reviews belong to listings. If someone leaves a review for a listing, the event saves both the review id (as eventable_id) and the listing id (as parent_id). So I can link to both in the view.

My problem is that if I deleted the listing, the review event remains, and rails throws an error (can't find listing with id 25, for example).

Here is my listing model:

class Listing < ApplicationRecord
  belongs_to :user
  has_many :reviews, dependent: :destroy
  has_many :activities, as: :eventable, dependent: :destroy

My reviews model also has
has_many :activities, as: :eventable, dependent: :destroy

The issue I'm having is that the listing gets deleted, and the reviews and events associated with that listing get deleted. But the events associated with the reviews do not get deleted. Did I do something wrong in the association?

Is this something where I would need to use a cascade? I do not understand the differences.
*Update, it seems like the immediate events are not being deleted along with the listing as well.

So I managed to fix this by changing it from :destroy to :delete_all.
has_many :activities, as: :eventable, dependent: :delete_all


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