add roles to admin panel

app/admin/roles.rb

@@ -0,0 +1,3 @@
+ActiveAdmin.register Role do
+  permit_params :name
+end

app/admin/users.rb

@@ -1,5 +1,5 @@
 ActiveAdmin.register User do
-  permit_params :email, :name
+  permit_params :email, :name, role_ids: []
 
   index do
     selectable_column
@@ -17,7 +17,8 @@ ActiveAdmin.register User do
   form do |f|
     f.inputs do
       f.input :email
-      f.input :email
+      f.input :name
+      f.input :roles, as: :check_boxes
     end
     f.actions
   end

app/models/role.rb

@@ -0,0 +1,18 @@
+# == Schema Information
+#
+# Table name: roles
+#
+#  id         :bigint           not null, primary key
+#  name       :string
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
+#
+# Indexes
+#
+#  index_roles_on_name  (name) UNIQUE
+#
+class Role < ApplicationRecord
+  has_and_belongs_to_many :users
+
+  validates :name, presence: true, uniqueness: true
+end

app/models/user.rb

@@ -26,5 +26,7 @@ class User < ApplicationRecord
          :omniauthable,
          omniauth_providers: [:google_oauth2]
 
+  has_and_belongs_to_many :roles
+
   validates :name, presence: true
 end