Add `ActiveRecord::Base.suppress` to allow save events to be suppressed within a specified block. #18910

perceptec · 2015-02-12T05:30:12Z

georgeclaghorn · 2015-02-12T05:46:05Z

activerecord/test/cases/suppressor_test.rb

+  def test_suppresses_creation_of_related_record_on_after_create_callback
+    count = Notification.count
+    Notification.suppress { UserWithNotification.create! }
+    assert_equal count, Notification.count


Should assert that other models used in the suppress block -- in this case, User -- are unaffected:

assert_difference -> { User.count } do assert_no_difference -> { Notification.count } do Notification.suppress { UserWithNotification.create! } end end

perceptec · 2015-02-12T15:56:52Z

Thanks for the feedback, @georgeclaghorn and @kaspth.

kaspth · 2015-02-12T16:37:53Z

activerecord/lib/active_record/suppressor.rb

@@ -0,0 +1,57 @@
+module ActiveRecord
+  # ActiveRecord::Suppressor allows save events to be suppressed within a


I still think callbacks is clearer than events here 😄

That's more along the lines of what I originally had and again included, but lost when I moved the comment up to the class level. There's a stray line break in there too, so I'll fix once there's feedback on this commit.

If you want you can blame the original author here: #18847. 😄

Ah, let's give him a pass. But just this once 😉

kaspth · 2015-02-12T16:50:31Z

Left some notes, otherwise this looks good. Thanks for working on it 😄

Just so you know, it doesn't seem like GitHub supports "closes #x" in the Pull Request title: https://github.com/blog/1506-closing-issues-via-pull-requests. But the issue will close when this is merged, because you've put the issue number in your commit message.

mcmire · 2015-02-13T18:39:26Z

Does .suppress cancel all callbacks, or only certain callbacks?

georgeclaghorn · 2015-02-14T03:09:03Z

activerecord/CHANGELOG.md

@@ -1,3 +1,34 @@
+*   Add `ActiveRecord::Base.suppress` to allow save callbacks to be suppressed


It prevents saves, not save callbacks. It is useful to prevent undesirable saves happening in callbacks.

My bad, I suggested this. My mental model was off on what this actually does.

mcmire · 2015-02-15T08:15:09Z

I don't really agree with this change. First, I don't think that there's a legitimate use case for this, and second, I don't think this is the correct solution to this problem.

I have rarely ever seen a case where I've added a callback that involves saving another record and then for some reason I don't want that save to occur. I can see this happening in tests, but that is easily solved by stubbing the method that performs the save (Notification.create!, in the example). Now, if I did have a need to prevent this from happening in production code, it would actually tell me that these two components are too tightly coupled, and it would encourage me to break them apart into a higher level object (CreateCommentWithNotification, for instance) so that I had the freedom to only create the comment if I wanted to. In other words, I think this change encourages bad design.

Even if that were not the case, I think that the usage is weird. As a reader of this code, it seems like the context around the use of suppress would not be immediately clear. In other words, if I saw the Notification.suppress line, I'd have to know that it's tied back to the after_create... inside of Comment. I would immediately ask myself, if we are modifying the behavior of Comment, why should we have to tell Notification to do something? We're reaching inside of Notification from a completely different class. On top of this, this seems like a shotgun solution. What if there are other things happening in the block that also save notifications? Wouldn't it be better to be able to ask Comment to disable the callback in question instead of having to know what that callback does and disable its contents?

Anyway... that's a bit of a moot point, because honestly I think both problems can be solved by making a separate class that encapsulates creating a comment and also creating a notification. Is it one more class? Sure, but you don't have to disable anything, and the intention is perfectly clear to other people reading the code.

kaspth · 2015-02-15T09:15:30Z

@mcmire please see the original issue #18847 for a use case and justification.

@perceptec can you add "Fixes #18847" to the description, so others will have an easier time evaluating this? 😄

dhh · 2015-02-18T17:27:51Z

Looking good @perceptec! Did @kaspth or @georgeclaghorn have any other comments, or are we good to merge?

@mcmire What @kaspth said. Use case is explained in the original issue.

rafaelfranca · 2015-02-18T17:35:05Z

activerecord/CHANGELOG.md

+      end
+    end
+
+    Closes #18847.


You don't need to point to the issue at the changelog since it is a new feature

georgeclaghorn · 2015-02-18T17:40:05Z

Looks good to me!

dhh · 2015-02-18T17:40:33Z

@mcmire The general principle I apply for this design is "the exception must carry the weight of its own work". If you create a new CreateCommentWithNotifications object, you're pushing the weight of the work onto the default case. That's not proportional in my book.

kaspth · 2015-02-18T19:24:35Z

Once @georgeclaghorn's and @rafaelfranca's concerns are addressed then 👍

Oh, and we'll need a rebase @perceptec 😄

perceptec · 2015-02-18T21:22:33Z

This one's been slippery to define. "save callbacks" was intended more in a compound sense (if a bit of a cop-out).

Will this work? (Since there's already been discussion/confusion around the intended functionality.)

Add ActiveRecord::Base.suppress to prevent the receiver from being saved during callbacks generated by a given block.

No matter what we come up with for a definition, I think the code itself will be more illustrative...

georgeclaghorn · 2015-02-18T21:25:47Z

Add ActiveRecord::Base.suppress to prevent the receiver from being saved during callbacks generated by a given block.

It's not necessary to mention callbacks at all. ActiveRecord::Base.suppress prevents saves for objects of the receiving class inside the block, regardless of where the saves occur. This still suggests that it only suppresses saves in callbacks.

rafaelfranca · 2015-02-18T21:26:44Z

Maybe Add ActiveRecord::Base.suppress to prevent the receiver from being saved during the given block.

perceptec · 2015-02-18T21:29:30Z

@georgeclaghorn True, is everybody okay with @rafaelfranca's edit?

dhh · 2015-02-18T21:29:33Z

What George said. Let’s just focus on suppress = no saving of records.

On Feb 18, 2015, at 13:26, George Claghorn notifications@github.com wrote:

Add ActiveRecord::Base.suppress to prevent the receiver from being saved during callbacks generated by a given block.

It's not necessary to mention callbacks at all. ActiveRecord::Base.suppress prevents saves for objects of the receiving class inside the block, regardless of where the saves occur. This still suggests that it only suppresses saves in callbacks.

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georgeclaghorn · 2015-02-18T21:30:38Z

👍

georgeclaghorn · 2015-02-19T04:33:30Z

activerecord/CHANGELOG.md

+      belongs_to :commentable, polymorphic: true
+      after_create -> { Notification.create! comment: self,
+        recipients: commentable.recipients }
+    end


Indent code examples in this file by an extra four spaces.

Add `ActiveRecord::Base.suppress` to allow save events to be suppressed within a specified block.

kaspth · 2015-02-19T11:34:37Z

Boom! Well done @perceptec 😄

Kasper

Den 19/02/2015 kl. 12.08 skrev Rafael Mendonça França notifications@github.com:

Merged #18910.

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dhh · 2015-02-19T16:30:58Z

Great job 👏

jeremy · 2016-05-23T06:59:44Z

(Removed a disparaging comment about the feature that was thoughtlessly posted on the implementation work done here. Please contribute to discussion on the original issue #18847.)

georgeclaghorn reviewed Feb 12, 2015
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kaspth added the activerecord label Feb 12, 2015

kaspth added this to the 5.0.0 milestone Feb 12, 2015

kaspth reviewed Feb 12, 2015
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perceptec changed the title ~~Add ActiveRecord::Base.suppress to allow save events to be suppressed within a specified block. Closes #18847.~~ Add ActiveRecord::Base.suppress to allow save events to be suppressed within a specified block. Feb 12, 2015

georgeclaghorn reviewed Feb 14, 2015
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rafaelfranca reviewed Feb 18, 2015
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Add ActiveRecord::Base.suppress

b9a1e9a

georgeclaghorn reviewed Feb 19, 2015
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rafaelfranca merged commit b9a1e9a into rails:master Feb 19, 2015

rafaelfranca pushed a commit that referenced this pull request Feb 19, 2015

Merge pull request #18910 from perceptec/add_suppressor

41b9730

Add `ActiveRecord::Base.suppress` to allow save events to be suppressed within a specified block.

perceptec deleted the add_suppressor branch February 19, 2015 12:30

rafaelfranca modified the milestones: 5.0.0 [temp], 5.0.0 Dec 30, 2015

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Add `ActiveRecord::Base.suppress` to allow save events to be suppressed within a specified block. #18910

Add `ActiveRecord::Base.suppress` to allow save events to be suppressed within a specified block. #18910

perceptec commented Feb 12, 2015

georgeclaghorn Feb 12, 2015

perceptec commented Feb 12, 2015

kaspth Feb 12, 2015

perceptec Feb 12, 2015

kaspth Feb 12, 2015

kaspth commented Feb 12, 2015

mcmire commented Feb 13, 2015

georgeclaghorn Feb 14, 2015

kaspth Feb 14, 2015

mcmire commented Feb 15, 2015

kaspth commented Feb 15, 2015

dhh commented Feb 18, 2015

rafaelfranca Feb 18, 2015

georgeclaghorn commented Feb 18, 2015

dhh commented Feb 18, 2015

kaspth commented Feb 18, 2015

perceptec commented Feb 18, 2015

georgeclaghorn commented Feb 18, 2015

rafaelfranca commented Feb 18, 2015

perceptec commented Feb 18, 2015

dhh commented Feb 18, 2015

georgeclaghorn commented Feb 18, 2015

georgeclaghorn Feb 19, 2015

kaspth commented Feb 19, 2015

dhh commented Feb 19, 2015

jeremy commented May 23, 2016

		@@ -0,0 +1,57 @@
		module ActiveRecord
		# ActiveRecord::Suppressor allows save events to be suppressed within a

		@@ -1,3 +1,34 @@
		* Add `ActiveRecord::Base.suppress` to allow save callbacks to be suppressed

Add ActiveRecord::Base.suppress to allow save events to be suppressed within a specified block. #18910

Add ActiveRecord::Base.suppress to allow save events to be suppressed within a specified block. #18910

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jeremy commented May 23, 2016

Add `ActiveRecord::Base.suppress` to allow save events to be suppressed within a specified block. #18910

Add `ActiveRecord::Base.suppress` to allow save events to be suppressed within a specified block. #18910