Ruby on Rails simple multiple select using Tom-select

_form.html.erb

<%= form_with(model: product) do |form| %>
  <div>
    <%= form.label :name %>
    <%= form.text_field :name, class: "input" %>
  </div>

  <div>
    <%= form.label :categories %>
    <%= form.collection_select :category_ids, Category.all, :id, :name, {}, {multiple: true, id: 'category-select', class: "dropdown"} %>
  </div>

   <%= form.submit "Save product", class: "btn-primary" %>
<% end %>

product.rb

class Product < ApplicationRecord
  has_many :product_categories
  has_many :categories, through: :product_categories
end

products_controller.rb

class ProductsController < ApplicationController

  def create
    @product = Product.new(product_params)

    respond_to do |format|
      if @product.save
        format.html { redirect_to admin_product_url(@product), notice: "Product was successfully created." }
        format.json { render :show, status: :created, location: @product }
      else
        format.html { render :new, status: :unprocessable_entity }
        format.json { render json: @product.errors, status: :unprocessable_entity }
      end
    end
  end
  
  private
  
    def product_params
      params.require(:product).permit(:name, category_ids: [])
    end
end

select.js

import TomSelect from "tom-select"

document.addEventListener("turbo:load", () => {

  // Initializes a tom-select dropdown for elements with the 'category-select' ID.
  // The 'remove_button' plugin adds functionality to remove selected items.

  new TomSelect('#category-select', {
    plugins: ["remove_button"],
  });
})

Screen.Recording.2023-08-12.at.4.39.28.PM.mov