I have three models User, Roles and User Roles.
associations

class User < ApplicationRecord
  has_one :role, through: :user_role
  has_one :user_role, dependent: :destroy
 end
 
 class Role < ApplicationRecord
  has_many :user_roles
  has_many :user, through: :user_roles
 end

 class UserRole < ApplicationRecord
  belongs_to :admin_user
  belongs_to :role
 end

how do I create a form for user such that user can create new user with a role

I want to create a user with a single role. Most of the implementation I have seen has a add role button for multiple role. I want the user to have only one role