Enable waiting lists in meetings registrations

decidim-meetings/app/cells/decidim/meetings/join_waitlist_button/show.erb

@@ -0,0 +1,22 @@
+<% if model.registration_form_enabled? %>
+  <%= action_authorized_link_to(
+        :join_waitlist,
+        join_waitlist_meeting_registration_path(model),
+        class: button_classes
+      ) do %>
+    <%= icon(icon_name) %>
+    <%= i18n_join_waitlist_text %>
+  <% end %>
+<% else %>
+  <% unless options[:hide_modal] %>
+    <%= render :registration_modal %>
+  <% end %>
+  <%= action_authorized_button_to(
+        :join_waitlist,
+        content_tag(:span, "#{icon(icon_name)} #{i18n_join_waitlist_text}".html_safe),
+        "#",
+        class: button_classes,
+        data: { "dialog-open": current_user.present? ? "meeting-registration-confirm-#{model.id}" : "loginModal" },
+        resource: model
+      ) %>
+<% end %>

decidim-meetings/app/cells/decidim/meetings/join_waitlist_button_cell.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+module Decidim
+  module Meetings
+    # This cell renders the button to join a waitlist.
+    class JoinWaitlistButtonCell < Decidim::ViewModel
+      include MeetingCellsHelper
+
+      def show
+        return unless model.waitlist_enabled? && !model.has_available_slots? && model.can_be_joined_by?(current_user)
+        return if model.has_registration_for?(current_user)
+
+        render
+      end
+
+      private
+
+      def current_component
+        model.component
+      end
+
+      def button_classes
+        "button button__sm button__transparent-secondary w-full"
+      end
+
+      def i18n_join_waitlist_text
+        return if !model.waitlist_enabled? && model.has_available_slots?
+
+        I18n.t("add_to_waitlist", scope: "decidim.meetings.meetings.show")
+      end
+
+      def icon_name
+        "list-ordered"
+      end
+
+      def registration_form
+        @registration_form ||= Decidim::Meetings::JoinMeetingForm.new
+      end
+    end
+  end
+end

decidim-meetings/app/commands/decidim/meetings/admin/update_registrations.rb

@@ -27,6 +27,7 @@ def attributes
               available_slots: form.available_slots,
               reserved_slots: form.reserved_slots,
               registration_terms: form.registration_terms,
+              waitlist_enabled: form.waitlist_enabled,
               customize_registration_email: form.customize_registration_email
             }
             extra_params.merge!(registration_email_custom_content: form.registration_email_custom_content) if form.customize_registration_email

decidim-meetings/app/commands/decidim/meetings/join_waitlist.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module Decidim
+  module Meetings
+    # This command is executed when the user joins a meeting waitlist.
+    class JoinWaitlist < Decidim::Command
+      delegate :current_user, to: :form
+
+      def initialize(meeting, form)
+        @meeting = meeting
+        @user_group = Decidim::UserGroup.find_by(id: form.user_group_id)
+        @form = form
+      end
+
+      def call
+        return broadcast(:invalid) unless can_join_waitlist?
+        return broadcast(:invalid_form) unless form.valid?
+
+        meeting.with_lock do
+          create_waitlist_entry
+          send_waitlist_notification
+        end
+
+        broadcast(:ok)
+      end
+
+      private
+
+      attr_reader :meeting, :user_group, :form
+
+      def can_join_waitlist?
+        meeting.waitlist_enabled? &&
+          !meeting.registrations.exists?(user: current_user) &&
+          !meeting.has_available_slots?
+      end
+
+      def create_waitlist_entry
+        @registration = Decidim::Meetings::Registration.create!(
+          meeting:,
+          user: current_user,
+          user_group:,
+          public_participation: form.public_participation,
+          status: :waiting_list
+        )
+      end
+
+      def send_waitlist_notification
+        Decidim::EventsManager.publish(
+          event: "decidim.events.meetings.meeting_waitlist_added",
+          event_class: Decidim::Meetings::MeetingWaitlistNotificationEvent,
+          resource: meeting,
+          affected_users: [current_user]
+        )
+      end
+    end
+  end
+end

decidim-meetings/app/controllers/decidim/meetings/registrations_controller.rb

@@ -47,6 +47,24 @@ def create
         end
       end
 
+      def join_waitlist
+        enforce_permission_to(:join_waitlist, :meeting, meeting:)
+
+        @form = JoinMeetingForm.from_params(params).with_context(current_user:)
+
+        JoinWaitlist.call(meeting, @form) do
+          on(:ok) do
+            flash[:notice] = I18n.t("registrations.waitlist.success", scope: "decidim.meetings")
+            redirect_after_path
+          end
+
+          on(:invalid) do
+            flash.now[:alert] = I18n.t("registrations.waitlist.invalid", scope: "decidim.meetings")
+            redirect_after_path
+          end
+        end
+      end
+
       def destroy
         enforce_permission_to(:leave, :meeting, meeting:)
 

decidim-meetings/app/forms/decidim/meetings/admin/meeting_registrations_form.rb

@@ -14,6 +14,7 @@ class MeetingRegistrationsForm < Decidim::Form
         attribute :customize_registration_email, Boolean
         attribute :available_slots, Integer
         attribute :reserved_slots, Integer
+        attribute :waitlist_enabled, :boolean, default: false
 
         translatable_attribute :registration_terms, Decidim::Attributes::RichText
         translatable_attribute :registration_email_custom_content, Decidim::Attributes::RichText
@@ -22,6 +23,7 @@ class MeetingRegistrationsForm < Decidim::Form
         validates :available_slots, :reserved_slots, presence: true, if: ->(form) { form.registrations_enabled? }
         validates :available_slots, numericality: { greater_than_or_equal_to: 0 }, if: ->(form) { form.registrations_enabled? && form.available_slots.present? }
         validates :reserved_slots, numericality: { greater_than_or_equal_to: 0 }, if: ->(form) { form.registrations_enabled? }
+        validates :waitlist_enabled, inclusion: { in: [true, false] }
         validates :reserved_slots, numericality: { less_than_or_equal_to: :available_slots }, if: lambda { |form|
                                                                                                     form.registrations_enabled? &&
                                                                                                       form.reserved_slots.present? &&

decidim-meetings/app/models/decidim/meetings/registration.rb

@@ -14,9 +14,13 @@ class Registration < Meetings::ApplicationRecord
       validates :code, uniqueness: { allow_blank: true, scope: :meeting }
       validates :code, presence: true, on: :create
 
+      enum status: { registered: "registered", waitlisted: "waitlisted" }, _prefix: true
+
       before_validation :generate_code, on: :create
 
       scope :public_participant, -> { where(decidim_user_group_id: nil, public_participation: true) }
+      scope :registered, -> { where(status: :registered) }
+      scope :waiting_list, -> { where(status: :waiting_list).order(:created_at) }
 
       def self.user_collection(user)
         where(decidim_user_id: user.id)

decidim-meetings/app/views/decidim/meetings/admin/registrations/_form.html.erb

@@ -18,6 +18,10 @@
         <%= form.number_field :reserved_slots, help_text: t(".reserved_slots_help") %>
       </div>
 
+      <div class="row column">
+        <%= form.check_box :waitlist_enabled, help_text: t(".waitlist_enabled_help") %>
+      </div>
+
       <div class="row column">
         <%= form.check_box :customize_registration_email %>
       </div>

decidim-meetings/app/views/decidim/meetings/meetings/_meeting_aside.html.erb

@@ -6,6 +6,12 @@
   </section>
 <% end %>
 
+<% if meeting.waitlist_enabled? && !meeting.has_available_slots? && meeting.can_be_joined_by?(current_user) %>
+  <section class="layout-aside__section layout-aside__buttons layout-aside__ctas-buttons" data-sticky-buttons>
+    <%= cell "decidim/meetings/join_waitlist_button", meeting, hide_modal: local_assigns[:hide_modal] %>
+  </section>
+<% end %>
+
 <% if (meeting.closed? && meeting.closing_visible?) || (registration.present? && registration.meeting.component.settings.registration_code_enabled) || (meeting.services.any?) %>
 <section class="layout-aside__section layout-aside__buttons">
   <% if meeting.closed? && meeting.closing_visible? %>

decidim-meetings/config/locales/en.yml

@@ -431,6 +431,8 @@ en:
             reserved_slots_help: Leave it to 0 if you do not have reserved slots.
             reserved_slots_less_than: Must be less than or equal to %{count}
             title: Registrations
+            waitlist_enabled: Waitlist enabled
+            waitlist_enabled_help: If enabled, the user will be able to join the waitlist when the available slots are full.
           update:
             invalid: There was a problem saving the registration settings.
             success: Meeting registrations settings successfully saved.
@@ -592,6 +594,7 @@ en:
           cancel: Cancel
           confirm: Confirm
         show:
+          add_to_waitlist: Add to waitlist
           attendees: Attendees count
           contributions: Contributions count
           join: Register

decidim-meetings/db/migrate/20250214110525_add_waitlist_enabled_to_decidim_meetings.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddWaitlistEnabledToDecidimMeetings < ActiveRecord::Migration[7.0]
+  def change
+    add_column :decidim_meetings_meetings, :waitlist_enabled, :boolean, default: false, null: false
+  end
+end

decidim-meetings/db/migrate/20250214113208_add_status_to_registrations_to_decidim_meetings_registrations.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class AddStatusToRegistrationsToDecidimMeetingsRegistrations < ActiveRecord::Migration[7.0]
+  def change
+    add_column :decidim_meetings_registrations, :status, :string, default: "registered", null: false
+    add_index :decidim_meetings_registrations, :status
+  end
+end

decidim-meetings/lib/decidim/meetings/engine.rb

@@ -26,6 +26,7 @@ class Engine < ::Rails::Engine
               get :decline_invitation
               get :join, action: :show
               post :answer
+              post :join_waitlist
             end
           end
           resources :versions, only: [:show]