Rails: before_save - Stack level too deep

Question

I have this simple model:

class Post < ApplicationRecord

    after_create_commit :process
    before_save :re_process, on: :update

    has_one :processed, class_name: 'Post::Process'

    def process
        self.processed.destroy if self.processed
        processed = self.build_processed
        processed.save!
    end

    private

    def re_process
        self.process if self.title_changed?
    end

end

I get a Stack level to deep error everytime I create a new Post.

Now when I remove before_save :re_process, on: :update everything works fine.

Shouldn't this line take only affect when I am updating a post?

score 8 · Answer 1 · answered Sep 19 '17 at 15:38

8

Yes, the before_save you added on update it's working fine.

The problem is that you have the after_create_commit which the code saves the record after it was already created.

def process
  # here the Post was already created
  self.processed.destroy if self.processed
  processed = self.build_processed
  processed.save! # And here, you are updating the Post, so it triggers the re_process
end

So, basically, when you create a Post:

Saves the Post
Calls process callback (after_create_commit)
Calls re_process (because it's called in process method when doing save!)
Calls process again (because it's called in re_process)
And so on...

This loop is causing the Stack level to deep

Hope it helped!

answered Sep 19 '17 at 15:38

ascherman

1,602
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3. step: Why on earth does saving `processed` lead to trigger `before_save` for `self` (a post)? – jonhue Sep 19 '17 at 15:45
Shouldn't `before_save` only get triggered by `self.save!`? – jonhue Sep 19 '17 at 16:04
@ariel `on: :update or on: :create` does'nt work on before_save For this purpose, you have to use before_update – Nimish Gupta Sep 19 '17 at 17:26

Nimish Gupta · Accepted Answer · 2017-09-19T17:45:49.403

1

on: :update or on: :create doesn't work for before_save

For this purpose, you have to use before_update

class Post < ApplicationRecord

    after_create_commit :process
    before_update :re_process

    has_one :processed, class_name: 'Post::Process'

    def process
        self.processed.destroy if self.processed
        processed = self.build_processed
        processed.save!
    end

    private

    def re_process
        self.process if self.title_changed?
    end

end

If you are using on option with before_save, the callback will be executed no matter what is specified in on option.

Hope this helps

edited Sep 19 '17 at 17:45

answered Sep 19 '17 at 17:24

Nimish Gupta

2,735
1
9
17

Works, thank you! That's what I was trying to accomplish :) – jonhue Sep 19 '17 at 20:53
Glad to help you – Nimish Gupta Sep 20 '17 at 04:54

Rails: before_save - Stack level too deep

2 Answers2