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rails--rails/activemodel/CHANGELOG.md
claudiob 9c65c539e2 Add config to halt callback chain on return false
This stems from [a comment](rails#17227 (comment)) by @dhh.
In summary:

* New Rails 5.0 apps will not accept `return false` as a way to halt callback chains, and will not display a deprecation warning.
* Existing apps ported to Rails 5.0 will still accept `return false` as a way to halt callback chains, albeit with a deprecation warning.

For this purpose, this commit introduces a Rails configuration option:

```ruby
config.active_support.halt_callback_chains_on_return_false
```

For new Rails 5.0 apps, this option will be set to `false` by a new initializer
`config/initializers/callback_terminator.rb`:

```ruby
Rails.application.config.active_support.halt_callback_chains_on_return_false = false
```

For existing apps ported to Rails 5.0, the initializers above will not exist.
Even running `rake rails:update` will not create this initializer.

Since the default value of `halt_callback_chains_on_return_false` is set to
`true`, these apps will still accept `return true` as a way to halt callback
chains, displaying a deprecation warning.

Developers will be able to switch to the new behavior (and stop the warning)
by manually adding the line above to their `config/application.rb`.

A gist with the suggested release notes to add to Rails 5.0 after this
commit is available at https://gist.github.com/claudiob/614c59409fb7d11f2931
2015-01-02 15:31:56 -08:00

648 B

  • Change the way in which callback chains can be halted.

    The preferred method to halt a callback chain from now on is to explicitly throw(:abort). In the past, returning false in an ActiveModel or ActiveModel::Validations before_ callback had the side effect of halting the callback chain. This is not recommended anymore and, depending on the value of the config.active_support.halt_callback_chains_on_return_false option, will either not work at all or display a deprecation warning.

Please check 4-2-stable for previous changes.