Noticed

🎉 Notifications for your Ruby on Rails app.

Currently, we support these notification delivery methods out of the box:

Database
Email
ActionCable channels
Slack
Microsoft Teams
Twilio (SMS)
Vonage / Nexmo (SMS)
iOS Apple Push Notifications
Firebase Cloud Messaging (Android and more)

And you can easily add new notification types for any other delivery methods.

🎬 Screencast

Watch Screencast

🚀 Installation

Run the following command to add Noticed to your Gemfile

bundle add "noticed"

To save notifications to your database, use the following command to generate a Notification model.

rails generate noticed:model

This will generate a Notification model and instructions for associating User models with the notifications table.

📝 Usage

To generate a notification object, simply run:

rails generate noticed:notification CommentNotification

Sending Notifications

To send a notification to a user:

# Instantiate a new notification
notification = CommentNotification.with(comment: @comment)

# Deliver notification in background job
notification.deliver_later(@comment.post.author)

# Deliver notification immediately
notification.deliver(@comment.post.author)

# Deliver notification to multiple recipients
notification.deliver_later(User.all)

This will instantiate a new notification with the comment stored in the notification's params.

Each delivery method is able to transform this metadata that's best for the format. For example, the database may simply store the comment so it can be linked when rendering in the navbar. The websocket mechanism may transform this into a browser notification or insert it into the navbar.

Notification Objects

Notifications inherit from Noticed::Base. This provides all their functionality and allows them to be delivered.

To add delivery methods, simply include the module for the delivery methods you would like to use.

class CommentNotification < Noticed::Base
  deliver_by :database
  deliver_by :action_cable
  deliver_by :email, mailer: 'CommentMailer', if: :email_notifications?

  # I18n helpers
  def message
    t(".message")
  end

  # URL helpers are accessible in notifications
  # Don't forget to set your default_url_options so Rails knows how to generate urls
  def url
    post_path(params[:post])
  end

  def email_notifications?
    !!recipient.preferences[:email]
  end

  after_deliver do
    # Anything you want
  end
end

Shared Options

if: :method_name - Calls method_name and cancels delivery method if false is returned
unless: :method_name - Calls method_name and cancels delivery method if true is returned
delay: ActiveSupport::Duration - Delays the delivery for the given duration of time
delay: :method_name - Calls method_name which should return an ActiveSupport::Duration and delays the delivery for the given duration of time

Helper Methods

You can define helper methods inside your Notification object to make it easier to render.

URL Helpers

Rails url helpers are included in notification classes by default so you have full access to them just like you would in your controllers and views.

Don't forget, you'll need to configure default_url_options in order for Rails to know what host and port to use when generating URLs.

Rails.application.routes.default_url_options[:host] = 'localhost:3000'

Callbacks

Like ActiveRecord, notifications have several different types of callbacks.

class CommentNotification < Noticed::Base
  deliver_by :database
  deliver_by :email, mailer: 'CommentMailer'

  # Callbacks for the entire delivery
  before_deliver :whatever
  around_deliver :whatever
  after_deliver :whatever

  # Callbacks for each delivery method
  before_database :whatever
  around_database :whatever
  after_database :whatever

  before_email :whatever
  around_email :whatever
  after_email :whatever
end

When using deliver_later callbacks will be run around queuing the delivery method jobs (not inside the jobs as they actually execute).

Defining custom delivery methods allows you to add callbacks that run inside the background job as each individual delivery is executed. See the Custom Delivery Methods section for more information.

Translations

We've added translate and t helpers like Rails has to provide an easy way of scoping translations. If the key starts with a period, it will automatically scope the key under notifications and the underscored name of the notification class it is used in.

For example:

t(".message") looks up en.notifications.new_comment.message

Or when notification class is in module:

t(".message") # in Admin::NewComment looks up en.notifications.admin.new_comment.message

User Preferences

You can use the if: and unless: options on your delivery methods to check the user's preferences and skip processing if they have disabled that type of notification.

For example:

class CommentNotification < Noticed::Base
  deliver_by :email, mailer: 'CommentMailer', if: :email_notifications?

  def email_notifications?
    recipient.email_notifications?
  end
end

🐞 Debugging

In order to figure out what's up when you run in to errors, you can set the debug parameter to true in your notification, which will give you a more detailed error message about what went wrong.

Example:

deliver_by :slack, debug: true

✅ Best Practices

Creating a notification from an Active Record callback

A common use case is to trigger a notification when a record is created. For example,

class Message < ApplicationRecord
  belongs_to :recipient, class_name: "User"

  after_create_commit :notify_recipient

  private

  def notify_recipient
    NewMessageNotification.with(message: self).deliver_later(recipient)
  end

If you are creating the notification on a background job (i.e. via #deliver_later), make sure you use a commit hook such as after_create_commit or after_commit.

Using after_create might cause the notification delivery methods to fail. This is because the job was enqueued while inside a database transaction, and the Message record might not yet be saved to the database.

A common symptom of this problem is undelivered notifications and the following error in your logs.

Discarded Noticed::DeliveryMethods::Email due to a ActiveJob::DeserializationError.

Renaming notifications

If you rename the class of a notification object your existing queries can break. This is because Noticed serializes the class name and sets it to the type column on the Notification record.

You can catch these errors at runtime by using YourNotificationClassName.name instead of hardcoding the string when performing a query.

Notification.where(type: YourNotificationClassName.name) # good
Notification.where(type: "YourNotificationClassName") # bad

When renaming a notification class you will need to backfill existing notifications to reference the new name.

Notification.where(type: "OldNotificationClassName").update_all(type: NewNotificationClassName.name)

🚛 Delivery Methods

The delivery methods are designed to be modular so you can customize the way each type gets delivered.

For example, emails will require a subject, body, and email address while an SMS requires a phone number and simple message. You can define the formats for each of these in your Notification and the delivery method will handle the processing of it.

Fallback Notifications

A common pattern is to deliver a notification via the database and then, after some time has passed, email the user if they have not yet read the notification. You can implement this functionality by combining multiple delivery methods, the delay option, and the conditional if / unless option.

class CommentNotification < Noticed::Base
  deliver_by :database
  deliver_by :email, mailer: 'CommentMailer', delay: 15.minutes, unless: :read?
end

Here a notification will be created immediately in the database (for display directly in your app). If the notification has not been read after 15 minutes, the email notification will be sent. If the notification has already been read in the app, the email will be skipped.

You can also configure multiple fallback options:

class CriticalSystemNotification < Noticed::Base
  deliver_by :database
  deliver_by :slack
  deliver_by :email, mailer: 'CriticalSystemMailer', delay: 10.minutes, if: :unread?
  deliver_by :twilio, delay: 20.minutes, if: :unread?
end

In this scenario, you have created an escalating notification system that

Immediately creates a record in the database (for display directly in the app)
Immediately issues a ping in Slack.
If the notification remains unread after 10 minutes, it emails the team.
If the notification remains unread after 20 minutes, it sends an SMS to the on-call phone.

You can mix and match the options and delivery methods to suit your application specific needs.

Please note that to implement this pattern, it is essential deliver_by :database is one among the different delivery methods specified. Without this, a database record of the notification will not be created.

🚚 Custom Delivery Methods

To generate a custom delivery method, simply run

rails generate noticed:delivery_method Discord

This will generate a new DeliveryMethods::Discord class inside the app/notifications/delivery_methods folder, which can be used to deliver notifications to Discord.

class DeliveryMethods::Discord < Noticed::DeliveryMethods::Base
  def deliver
    # Logic for sending a Discord notification
  end
end

You can use the custom delivery method thus created by adding a deliver_by line with a unique name and class option in your notification class.

class MyNotification < Noticed::Base
  deliver_by :discord, class: "DeliveryMethods::Discord"
end

Delivery methods have access to the following methods and attributes:

notification - The instance of the Notification. You can call methods on the notification to let the user easily override formatting and other functionality of the delivery method.
options - Any configuration options on the deliver_by line.
recipient - The object who should receive the notification. This is typically a User, Account, or other ActiveRecord model.
params - The params passed into the notification. This is details about the event that happened. For example, a user commenting on a post would have params of { user: User.first }

Validating options passed to Custom Delivery methods

The presence of the delivery method options is automatically validated if using the option(s) method.

If you want to validate that the passed options contain valid values, or to add any custom validations, override the self.validate!(delivery_method_options) method from the Noticed::DeliveryMethods::Base class.

class DeliveryMethods::Discord < Noticed::DeliveryMethods::Base
  option :username # Requires the username option to be passed

  def deliver
    # Logic for sending a Discord notification
  end

  def self.validate!(delivery_method_options)
    super # Don't forget to call super, otherwise option presence won't be validated

    # Custom validations
    if delivery_method_options[:username].blank?
      raise Noticed::ValidationError, 'the `username` option must be present'
    end
  end
end

class CommentNotification < Noticed::Base
  deliver_by :discord, class: 'DeliveryMethods::Discord'
end

Now it will raise an error because a required argument is missing.

To fix the error, the argument has to be passed correctly. For example:

class CommentNotification < Noticed::Base
  deliver_by :discord, class: 'DeliveryMethods::Discord', username: User.admin.username
end

Callbacks

Callbacks for delivery methods wrap the actual delivery of the notification. You can use before_deliver, around_deliver and after_deliver in your custom delivery methods.

class DeliveryMethods::Discord < Noticed::DeliveryMethods::Base
  after_deliver do
    # Do whatever you want
  end
end

📦 Database Model

The Notification database model includes several helpful features to make working with database notifications easier.

Class methods

Sorting notifications by newest first:

user.notifications.newest_first

Query for read or unread notifications:

user.notifications.read
user.notifications.unread

Marking all notifications as read or unread:

user.notifications.mark_as_read!
user.notifications.mark_as_unread!

Instance methods

Convert back into a Noticed notification object:

@notification.to_notification

Mark notification as read / unread:

@notification.mark_as_read!
@notification.mark_as_unread!

Check if read / unread:

@notification.read?
@notification.unread?

Associating Notifications

Adding notification associations to your models makes querying and deleting notifications easy and is a pretty critical feature of most applications.

For example, in most cases, you'll want to delete notifications for records that are destroyed.

We'll need two associations for this:

Notifications where the record is the recipient
Notifications where the record is in the notification params

For example, we can query the notifications and delete them on destroy like so:

class Post < ApplicationRecord
  # Standard association for deleting notifications when you're the recipient
  has_many :notifications, as: :recipient, dependent: :destroy

  # Helper for associating and destroying Notification records where(params: {post: self})
  has_noticed_notifications

  # You can override the param_name, the notification model name, or disable the before_destroy callback
  has_noticed_notifications param_name: :parent, destroy: false, model_name: "Notification"
end

# Create a CommentNotification with a post param
CommentNotification.with(post: @post).deliver(user)
# Lookup Notifications where params: {post: @post}
@post.notifications_as_post

CommentNotification.with(parent: @post).deliver(user)
@post.notifications_as_parent

Handling Deleted Records

If you create a notification but delete the associated record and forgot has_noticed_notifications on the model, the jobs for sending the notification will not be able to find the record when ActiveJob deserializes. You can discard the job on these errors by adding the following to ApplicationJob:

class ApplicationJob < ActiveJob::Base
  discard_on ActiveJob::DeserializationError
end

🙏 Contributing

This project uses Standard for formatting Ruby code. Please make sure to run standardrb before submitting pull requests.

Running tests against multiple databases locally:

DATABASE_URL=sqlite3:noticed_test rails test
DATABASE_URL=mysql2://root:@127.0.0.1/noticed_test rails test
DATABASE_URL=postgres://127.0.0.1/noticed_test rails test

📝 License

The gem is available as open source under the terms of the MIT License.

igor-alexandrov/noticed