CODEWITHSUNDEEP
ruby-on-railsinheritance
kinsomicrote
kinsomicrote

Reputation: 187

Invalid single-table inheritance type: dog is not a subclass of Pet

I have not idea what is going wrong here. I generated the new app to check something out. I generated everything using rails g scaffold Pet name:string type:string When I try creating a new pet I get the error:

Invalid single-table inheritance type: dog is not a subclass of Pet

What could be the issue?

Migration

class CreatePets < ActiveRecord::Migration
  def change
    create_table :pets do |t|
      t.string :name
      t.string :type

      t.timestamps null: false
    end
  end
end

Controller

class PetsController < ApplicationController
      before_action :set_pet, only: [:show, :edit, :update, :destroy]

      # GET /pets
      # GET /pets.json
      def index
        @pets = Pet.all
      end

      # GET /pets/1
      # GET /pets/1.json
      def show
      end

      # GET /pets/new
      def new
        @pet = Pet.new
      end

      # GET /pets/1/edit
      def edit
      end

      # POST /pets
      # POST /pets.json
      def create
        @pet = Pet.new(pet_params)

        respond_to do |format|
          if @pet.save
            format.html { redirect_to @pet, notice: 'Pet was successfully created.' }
            format.json { render :show, status: :created, location: @pet }
          else
            format.html { render :new }
            format.json { render json: @pet.errors, status: :unprocessable_entity }
          end
        end
      end

      # PATCH/PUT /pets/1
      # PATCH/PUT /pets/1.json
      def update
        respond_to do |format|
          if @pet.update(pet_params)
            format.html { redirect_to @pet, notice: 'Pet was successfully updated.' }
            format.json { render :show, status: :ok, location: @pet }
          else
            format.html { render :edit }
            format.json { render json: @pet.errors, status: :unprocessable_entity }
          end
        end
      end

      # DELETE /pets/1
      # DELETE /pets/1.json
      def destroy
        @pet.destroy
        respond_to do |format|
          format.html { redirect_to pets_url, notice: 'Pet was successfully destroyed.' }
          format.json { head :no_content }
        end
      end

      private
        # Use callbacks to share common setup or constraints between actions.
        def set_pet
          @pet = Pet.find(params[:id])
        end

        # Never trust parameters from the scary internet, only allow the white list through.
        def pet_params
          params.require(:pet).permit(:name, :type)
        end
    end

Model:

    class Pet < ActiveRecord::Base
    end

Upvotes: 0

Views: 1208

Answers (1)

chaitanya
chaitanya

Reputation: 1984

Rename your column "type" to "pet_type" or something else.

type is used by rails for single table inheritance.

STI is basically the idea of using a single table to reflect multiple models that inherit from a base model, which itself inherits from ActiveRecord::Base. In the database schema, sub-models are indicated by a single “type” column. In Rails, adding a “type” column in a database migration is sufficient (after writing the models) to let Rails know that you’re planning to implement STI

Upvotes: 2

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