FEATURE: consolidate group membership request notifications.

app/assets/javascripts/discourse-common/lib/icon-library.js.es6

@@ -36,7 +36,8 @@ const REPLACEMENTS = {
   "notification.watching_first_post": "far-dot-circle",
   "notification.group_message_summary": "users",
   "notification.post_approved": "check",
-  "notification.membership_request_accepted": "user-plus"
+  "notification.membership_request_accepted": "user-plus",
+  "notification.membership_request_consolidated": "users"
 };
 
 // TODO: use lib/svg_sprite/fa4-renames.json here

app/assets/javascripts/discourse/widgets/membership-request-consolidated-notification-item.js.es6

@@ -0,0 +1,25 @@
+import { createWidgetFrom } from "discourse/widgets/widget";
+import { DefaultNotificationItem } from "discourse/widgets/default-notification-item";
+import { userPath } from "discourse/lib/url";
+
+createWidgetFrom(
+  DefaultNotificationItem,
+  "membership-request-consolidated-notification-item",
+  {
+    url() {
+      return userPath(
+        `${this.attrs.username || this.currentUser.username}/messages`
+      );
+    },
+
+    text(notificationName, data) {
+      return I18n.t(
+        "notifications.membership_request_consolidated",
+        {
+          group_name: data.group_name,
+          count: parseInt(data.count, 10)
+        }
+      );
+    }
+  }
+);

app/models/notification.rb

@@ -4,6 +4,9 @@ class Notification < ActiveRecord::Base
   belongs_to :user
   belongs_to :topic
 
+  MEMBERSHIP_REQUEST_CONSOLIDATION_WINDOW_HOURS = 24
+  MEMBERSHIP_REQUEST_CONSOLIDATION_THRESHOLD = 3
+
   validates_presence_of :data
   validates_presence_of :notification_type
 
@@ -20,11 +23,15 @@ class Notification < ActiveRecord::Base
 
   attr_accessor :skip_send_email
 
-  after_commit :send_email, on: :create
   after_commit :refresh_notification_count, on: [:create, :update, :destroy]
 
   after_commit(on: :create) do
-    DiscourseEvent.trigger(:notification_created, self)
+    consolidated = consolidate_membership_requests
+
+    unless consolidated
+      DiscourseEvent.trigger(:notification_created, self)
+      send_email
+    end
   end
 
   def self.ensure_consistency!
@@ -66,7 +73,8 @@ class Notification < ActiveRecord::Base
                         liked_consolidated: 19,
                         post_approved: 20,
                         code_review_commit_approved: 21,
-                        membership_request_accepted: 22
+                        membership_request_accepted: 22,
+                        membership_request_consolidated: 23
                        )
   end
 
@@ -226,6 +234,70 @@ class Notification < ActiveRecord::Base
     NotificationEmailer.process_notification(self) if !skip_send_email
   end
 
+  private
+
+  def consolidate_membership_requests
+    return unless unread_pm?
+
+    post_id = data_hash[:original_post_id]
+    return if post_id.blank?
+
+    custom_field = PostCustomField.select(:value).find_by(post_id: post_id, name: "requested_group_id")
+    return if custom_field.blank?
+
+    group_id = custom_field.value.to_i
+    group_name = Group.select(:name).find_by(id: group_id)&.name
+    return if group_name.blank?
+
+    consolidation_window = MEMBERSHIP_REQUEST_CONSOLIDATION_WINDOW_HOURS.hours.ago
+    timestamp = Time.zone.now
+    unread = user.notifications.unread
+
+    consolidated_notification = unread
+      .where("created_at > ? AND data::json ->> 'group_name' = ?", consolidation_window, group_name)
+      .find_by(notification_type: Notification.types[:membership_request_consolidated])
+
+    if consolidated_notification.present?
+      data = consolidated_notification.data_hash
+      data["count"] += 1
+
+      Notification.transaction do
+        consolidated_notification.update!(
+          data: data.to_json,
+          read: false,
+          updated_at: timestamp
+        )
+
+        destroy!
+      end
+
+      return true
+    end
+
+    notifications = unread
+      .where(notification_type: Notification.types[:private_message])
+      .where("created_at > ? AND data::json ->> 'topic_title' = ?", consolidation_window, data_hash[:topic_title])
+
+    return if notifications.count < MEMBERSHIP_REQUEST_CONSOLIDATION_THRESHOLD
+
+    Notification.transaction do
+      Notification.create!(
+        notification_type: Notification.types[:membership_request_consolidated],
+        user_id: user_id,
+        data: {
+          group_name: group_name,
+          count: notifications.count
+        }.to_json,
+        updated_at: timestamp,
+        created_at: timestamp
+      )
+
+      notifications.destroy_all
+    end
+
+    true
+  end
+
 end
 
 # == Schema Information

config/locales/client.en.yml

@@ -1782,6 +1782,7 @@ en:
       topic_reminder: "<span>{{username}}</span> {{description}}"
       watching_first_post: "<span>New Topic</span> {{description}}"
       membership_request_accepted: "Membership accepted in '{{group_name}}'"
+      membership_request_consolidated: "{{count}} open membership requests for '{{group_name}}'"
 
       group_message_summary:
         one: "{{count}} message in your {{group_name}} inbox"
@@ -1820,6 +1821,7 @@ en:
         topic_reminder: "topic reminder"
         liked_consolidated: "new likes"
         post_approved: "post approved"
+        membership_request_consolidated: "new membership requests"
 
     upload_selector:
       title: "Add an image"

spec/models/notification_spec.rb

@@ -355,5 +355,49 @@ describe Notification do
         expect(Notification.recent_report(user)).to contain_exactly(notification)
       end
     end
+
+    describe '#consolidate_membership_requests' do
+      fab!(:group) { Fabricate(:group, name: "XXsssssddd") }
+      fab!(:user) { Fabricate(:user) }
+      fab!(:post) { Fabricate(:post) }
+
+      def create_membership_request_notification
+        Notification.create(
+          notification_type: Notification.types[:private_message],
+          user_id: user.id,
+          data: {
+            topic_title: I18n.t('groups.request_membership_pm.title', group_name: group.name),
+            original_post_id: post.id
+          }.to_json,
+          updated_at: Time.zone.now,
+          created_at: Time.zone.now
+        )
+      end
+
+      before do
+        PostCustomField.create!(post_id: post.id, name: "requested_group_id", value: group.id)
+        create_membership_request_notification
+      end
+
+      it 'should consolidate membership requests to a new notification' do
+        notification = create_membership_request_notification
+        notification.reload
+
+        notification = create_membership_request_notification
+        expect { notification.reload }.to raise_error(ActiveRecord::RecordNotFound)
+
+        notification = Notification.last
+        expect(notification.notification_type).to eq(Notification.types[:membership_request_consolidated])
+
+        data = notification.data_hash
+        expect(data[:group_name]).to eq(group.name)
+        expect(data[:count]).to eq(3)
+
+        notification = create_membership_request_notification
+        expect { notification.reload }.to raise_error(ActiveRecord::RecordNotFound)
+
+        expect(Notification.last.data_hash[:count]).to eq(4)
+      end
+    end
   end
 end