title: Invalid single-table inheritance type: Rails
body: <p>I'm getting this error when trying to create a new Product in my Rails application. </p>
  
  <blockquote>
    <p>Invalid single-table inheritance type: Movie is not a subclass of
    Product</p>
  </blockquote>
  
  <p>How can I resolve this?</p>
  
  <p><img src="https://i.stack.imgur.com/C3wD5.png" alt="enter image description here"></p>
  
  <p>controller</p>
  
  <pre><code>class ProductsController &lt; ApplicationController
    before_action :set_product, only: [:show, :edit, :update, :destroy]
  
    # GET /products
    # GET /products.json
    def index
      @products = Product.all
    end
  
    # GET /products/1
    # GET /products/1.json
    def show
    end
  
    # GET /products/new
    def new
      @product = Product.new
    end
  
    # GET /products/1/edit
    def edit
    end
  
    # POST /products
    # POST /products.json
    def create
      @product = Product.new(product_params)
  
      respond_to do |format|
        if @product.save
          format.html { redirect_to @product, notice: 'Product was successfully created.' }
          format.json { render action: 'show', status: :created, location: @product }
        else
          format.html { render action: 'new' }
          format.json { render json: @product.errors, status: :unprocessable_entity }
        end
      end
    end
  
    # PATCH/PUT /products/1
    # PATCH/PUT /products/1.json
    def update
      respond_to do |format|
        if @product.update(product_params)
          format.html { redirect_to @product, notice: 'Product was successfully updated.' }
          format.json { head :no_content }
        else
          format.html { render action: 'edit' }
          format.json { render json: @product.errors, status: :unprocessable_entity }
        end
      end
    end
  
    # DELETE /products/1
    # DELETE /products/1.json
    def destroy
      @product.destroy
      respond_to do |format|
        format.html { redirect_to products_url }
        format.json { head :no_content }
      end
    end
  
    private
      # Use callbacks to share common setup or constraints between actions.
      def set_product
        @product = Product.find(params[:id])
      end
  
      # Never trust parameters from the scary internet, only allow the white list through.
      def product_params
        params.require(:product).permit(:title, :artist, :type, :release_date, :category, :publisher, :format, :description, :sale_price, :rental_price)
      end
  end
  </code></pre>
  
  <p>migration</p>
  
  <pre><code>class CreateProducts &lt; ActiveRecord::Migration
    def change
      create_table :products do |t|
        t.string :title
        t.string :artist
        t.string :type
        t.date :release_date
        t.string :category
        t.string :publisher
        t.string :format
        t.text :description
        t.decimal :sale_price
        t.decimal :rental_price
  
        t.timestamps
      end
    end
  end
  </code></pre>