---
title: "Gotcha with after_commit callback in Rails"
description: "Gotcha with after_commit callback in Rails"
canonical_url: "https://www.bigbinary.com/blog/gotcha-with-after_commit-callback-in-rails"
markdown_url: "https://www.bigbinary.com/blog/gotcha-with-after_commit-callback-in-rails.md"
---

# Gotcha with after_commit callback in Rails

Gotcha with after_commit callback in Rails

- Author: Prathamesh Sonpatki
- Published: March 1, 2015
- Categories: Rails

`after_commit` callback in Rails is triggered after the end of transaction.

For eg. I have a Post model for which the number of lines of the content are
calculated in the `after_commit` callback:

```ruby
class Post < ActiveRecord::Base
  after_commit :calculate_total_lines, if: -> (post) { post.previous_changes.include?(:content) }

  def calculate_total_lines
    update! total_lines: content.split("\n").length
  end
end
```

```ruby
post = Post.create! content: "Lets discuss Rails 5.\n", author: 'Prathamesh'
assert_equal 1, post.total_lines
```

Now lets wrap the creation of post inside a transaction block:

```ruby
Post.transaction do
  post = Post.create! content: "Lets discuss Rails 5.\n", author: 'Prathamesh'
  assert_equal 1, post.total_lines
end
```

The test will fail now.

```ruby
#   1) Failure:
# BugTest#test_within_transaction [after_commit_test.rb:45]:
# Expected: 1
#   Actual: nil
```

Why? Lets recall. `after_commit` callback will get executed after the end of
transaction.

So until all the code inside transaction is completed, the callback is not going
to get executed.

Here is a
[gist](https://gist.github.com/prathamesh-sonpatki/69b00155d3990e3e507e) with
complete test.

Next time you are using an `after_commit` callback and a `transaction`, make
sure that code inside the transaction is not dependent on the result of the
callback.

## Links

- [Human page](https://www.bigbinary.com/blog/gotcha-with-after_commit-callback-in-rails)