README.md
# Wisper::ActiveRecord
[](http://badge.fury.io/rb/wisper-activerecord)
[](https://codeclimate.com/github/krisleech/wisper-activerecord)
[](https://travis-ci.org/krisleech/wisper-activerecord)
Transparently publish model lifecycle events to subscribers.
Using Wisper events is a better alternative to ActiveRecord callbacks and Observers.
Listeners are subscribed to models at runtime.
## Installation
```ruby
gem 'wisper-activerecord'
```
## Usage
### Setup a publisher
```ruby
class Meeting < ActiveRecord::Base
include Wisper.model
# ...
end
```
If you wish all models to broadcast events without having to explicitly include
`Wisper.model` add the following to an initializer:
```ruby
Wisper::ActiveRecord.extend_all
```
### Subscribing
Subscribe a listener to model instances:
```ruby
meeting = Meeting.new
meeting.subscribe(Auditor.new)
```
Subscribe a block to model instances:
```ruby
meeting.on(:create_meeting_successful) { |meeting| ... }
```
Subscribe a listener to _all_ instances of a model:
```ruby
Meeting.subscribe(Auditor.new)
```
Please refer to the [Wisper README](https://github.com/krisleech/wisper) for full details about subscribing.
The events which are automatically broadcast are:
* `after_create`
* `after_update`
* `after_destroy`
* `create_<model_name>_{successful, failed}`
* `update_<model_name>_{successful, failed}`
* `destroy_<model_name>_successful`
* `<model_name>_committed`
* `after_commit`
* `after_rollback`
### Reacting to Events
To receive an event the listener must implement a method matching the name of
the event with a single argument, the instance of the model.
```ruby
def create_meeting_successful(meeting)
# ...
end
```
## Example
### Controller
```ruby
class MeetingsController < ApplicationController
def new
@meeting = Meeting.new
end
def create
@meeting = Meeting.new(params[:meeting])
@meeting.subscribe(Auditor.new)
@meeting.on(:create_meeting_successful) { redirect_to meeting_path }
@meeting.on(:create_meeting_failed) { render action: :new }
@meeting.save
end
def edit
@meeting = Meeting.find(params[:id])
end
def update
@meeting = Meeting.find(params[:id])
@meeting.subscribe(Auditor.new)
@meeting.on(:update_meeting_successful) { redirect_to meeting_path }
@meeting.on(:update_meeting_failed) { render :action => :edit }
@meeting.update_attributes(params[:meeting])
end
end
```
Using `on` to subscribe a block to handle the response is optional,
you can still use `if @meeting.save` if you prefer.
### Listener
**Which simply records an audit in memory**
```ruby
class Auditor
def after_create(subject)
push_audit_for('create', subject)
end
def after_update(subject)
push_audit_for('update', subject)
end
def after_destroy(subject)
push_audit_for('destroy', subject)
end
def self.audit
@audit ||= []
end
private
def push_audit_for(action, subject)
self.class.audit.push(audit_for(action, subject))
end
def audit_for(action, subject)
{
action: action,
subject_id: subject.id,
subject_class: subject.class.to_s,
changes: subject.previous_changes,
created_at: Time.now
}
end
end
```
**Do some CRUD**
```ruby
Meeting.create(:description => 'Team Retrospective', :starts_at => Time.now + 2.days)
meeting = Meeting.find(1)
meeting.starts_at = Time.now + 2.months
meeting.save
```
**And check the audit**
```ruby
Auditor.audit # => [...]
```
## Notes on Testing
### ActiveRecord <= 4.0
This gem makes use of ActiveRecord's `after_commit` lifecycle hook to broadcast
events, which will create issues when testing with transactional fixtures.
Unless you also include the [test_after_commit gem](https://github.com/grosser/test_after_commit)
ActiveRecord models will not broadcast any lifecycle events within your tests.
## Compatibility
Tested on CRuby, Rubinius and JRuby for ActiveRecord ~> 3.0, ~> 4.0, and ~> 5.0.
See the CI [build status](https://travis-ci.org/krisleech/wisper-activerecord) for more information.
## Contributing
Please submit a Pull Request with specs.
### Running the specs
```
bundle exec rspec
```