Add recipients feature for defining recipients inside the notifier (#459)

* Add feature for defining recipients inside the notifier
* Also support blocks

Author: excid3

CHANGELOG.md

@@ -1,5 +1,28 @@
 ### Unreleased
 
+* Add `recipients` feature to let Notifiers determine their recipients
+
+```ruby
+class CommentNotifier < ApplicationNotifier
+  # Notify all the commenters on this post except the new comment author
+
+  # Can be given a lambda or Proc
+  recipients ->{ params[:comment].post.commenters.excluding(params[:comment].user).distinct }
+
+  # Can be given a block
+  recipients do
+    params[:comment].post.commenters.excluding(params[:comment].user).distinct
+  end
+
+  # Or can call a method
+  recipients :fetch_recipients
+
+  def fetch_recipients
+    params[:comment].post.commenters.excluding(params[:comment].user).distinct
+  end
+end
+```
+
 ### 2.3.3
 
 * Use `public_send` for Email delivery so it doesn't accidentally call private methods.

app/models/concerns/noticed/deliverable.rb

@@ -6,6 +6,7 @@ module Deliverable
       class_attribute :bulk_delivery_methods, instance_writer: false, default: {}
       class_attribute :delivery_methods, instance_writer: false, default: {}
       class_attribute :required_param_names, instance_writer: false, default: []
+      class_attribute :_recipients, instance_writer: false
     end
 
     class_methods do
@@ -39,6 +40,10 @@ def deliver_by(name, options = {})
         delivery_methods[name] = DeliverBy.new(name, config)
       end
 
+      def recipients(option = nil, &block)
+        self._recipients = block || option
+      end
+
       def required_params(*names)
         required_param_names.concat names
       end
@@ -79,6 +84,8 @@ def deliver(recipients = nil, **options)
     # CommentNotifier.deliver(User.all, wait: 5.minutes)
     # CommentNotifier.deliver(User.all, wait_until: 1.hour.from_now)
     def deliver(recipients = nil, enqueue_job: true, **options)
+      recipients ||= evaluate_recipients
+
       validate!
 
       transaction do
@@ -108,6 +115,16 @@ def deliver(recipients = nil, enqueue_job: true, **options)
     end
     alias_method :deliver_later, :deliver
 
+    def evaluate_recipients
+      return unless _recipients
+
+      if _recipients.respond_to?(:call)
+        instance_exec(&_recipients)
+      elsif _recipients.is_a?(Symbol) && respond_to?(_recipients)
+        send(_recipients)
+      end
+    end
+
     def recipient_attributes_for(recipient)
       {
         type: "#{self.class.name}::Notification",

test/dummy/app/notifiers/comment_notifier.rb

@@ -1,4 +1,6 @@
 class CommentNotifier < ApplicationNotifier
+  recipients -> { params[:recipients] }
+
   deliver_by :test
 
   # delivery_by :email, mailer: "UserMailer", method: "new_comment"

test/notifier_test.rb

@@ -3,6 +3,24 @@
 class NotifierTest < ActiveSupport::TestCase
   include ActiveJob::TestHelper
 
+  class RecipientsBlock < Noticed::Event
+    recipients do
+      params.fetch(:recipients)
+    end
+  end
+
+  class RecipientsLambda < Noticed::Event
+    recipients -> { params.fetch(:recipients) }
+  end
+
+  class RecipientsMethod < Noticed::Event
+    recipients :recipients
+
+    def recipients
+      params.fetch(:recipients)
+    end
+  end
+
   test "includes Rails urls" do
     assert_equal "http://localhost:3000/", SimpleNotifier.new.url
   end
@@ -40,6 +58,22 @@ class NotifierTest < ActiveSupport::TestCase
     assert_equal ["can't be blank"], notifier.errors[:record]
   end
 
+  test "recipients block" do
+    assert_equal [:foo, :bar], RecipientsBlock.with(recipients: [:foo, :bar]).evaluate_recipients
+  end
+
+  test "recipients lambda" do
+    assert_equal [:foo, :bar], RecipientsLambda.with(recipients: [:foo, :bar]).evaluate_recipients
+  end
+
+  test "recipients" do
+    assert_equal [:foo, :bar], RecipientsMethod.with(recipients: [:foo, :bar]).evaluate_recipients
+  end
+
+  test "deliver without recipients" do
+    ReceiptNotifier.deliver
+  end
+
   test "deliver creates an event" do
     assert_difference "Noticed::Event.count" do
       ReceiptNotifier.deliver(User.first)