Decouple to_params from AtomicInternalId concern

app/models/ci/pipeline.rb

@@ -14,7 +14,7 @@ module Ci
     belongs_to :auto_canceled_by, class_name: 'Ci::Pipeline'
     belongs_to :pipeline_schedule, class_name: 'Ci::PipelineSchedule'
-    has_internal_id :iid, scope: :project, presence: false, to_param: false, init: -> do |s|
+    has_internal_id :iid, scope: :project, presence: false, init: -> do |s|
       s&.project&.pipelines&.maximum(:iid) || s&.project&.pipelines.count
     end

app/models/concerns/atomic_internal_id.rb

@@ -25,7 +25,7 @@ module AtomicInternalId
   extend ActiveSupport::Concern
   module ClassMethods
-    def has_internal_id(column, scope:, init:, presence: true, to_param: true) # rubocop:disable Naming/PredicateName
+    def has_internal_id(column, scope:, init:, presence: true) # rubocop:disable Naming/PredicateName
       before_validation :"ensure_#{column}!", on: :create
       validates column, presence: presence, numericality: true
@@ -42,10 +42,6 @@ module AtomicInternalId
         read_attribute(column)
       end
-
-      define_method("to_param") do
-        read_attribute(column)
-      end if to_param
     end
   end
 end

app/models/concerns/iid_routes.rb

+module IIDRoutes
+  ##
+  # This automagically enforces all related routes to use `iid` instead of `id`
+  # If you want to use `iid` for some routes and `id` for other routes, this module should not to be included,
+  # instead you should define `iid` or `id` explictly at each route generators. e.g. pipeline_path(project.id, pipeline.iid)
+  def to_param
+    iid.to_s
+  end
+end

app/models/deployment.rb

 class Deployment < ActiveRecord::Base
   include AtomicInternalId
+  include IIDRoutes
   belongs_to :project, required: true
   belongs_to :environment, required: true

app/models/issue.rb

@@ -2,6 +2,7 @@ require 'carrierwave/orm/activerecord'
 class Issue < ActiveRecord::Base
   include AtomicInternalId
+  include IIDRoutes
   include Issuable
   include Noteable
   include Referable

app/models/merge_request.rb

 class MergeRequest < ActiveRecord::Base
   include AtomicInternalId
+  include IIDRoutes
   include Issuable
   include Noteable
   include Referable

app/models/milestone.rb

@@ -9,6 +9,7 @@ class Milestone < ActiveRecord::Base
   include CacheMarkdownField
   include AtomicInternalId
+  include IIDRoutes
   include Sortable
   include Referable
   include StripAttribute