如何在Rails中将关联复选框缺省设置为true

class User < ApplicationRecord
  has_and_belongs_to_many :roles
end

rails generate migration CreateJoinTableUsersRoles users roles

rails db:migrate

<%= form_with(model: user, local: true) do |form| %>
  <!-- 其他表单字段 -->

  <div class="field">
    <%= form.label :role_ids, 'Roles' %>
    <%= form.collection_check_boxes :role_ids, Role.all, :id, :name, checked: true %>
  </div>

  <div class="actions">
    <%= form.submit %>
  </div>
<% end %>

class UsersController < ApplicationController
  def create
    @user = User.new(user_params)

    if @user.save
      redirect_to @user, notice: 'User was successfully created.'
    else
      render :new
    end
  end

  private

  def user_params
    params.require(:user).permit(:name, role_ids: [])
  end
end