Rails Friendly Id - Couldn't find Category with id=electronics

Question

I'm trying to develop a app in Ruby on Rails 4.0 (already used older versions of this incredible framework) and I having some troubles.

I installed the FriendlyID gem and I think everything is okay, but I'm receiving errors when I try to test my app.

If I go to http://0.0.0.0:3000/categories/1, this works. But when I click in "edit" in this page, or just go to http://0.0.0.0:3000/categories/electronics (that's the slugged name of category with ID 1), I receive the following error:

Couldn't find Category with id=electronics
# Use callbacks to share common setup or constraints between actions.
def set_category
   @category = Category.find(params[:id])  #Here's pointed the error
end

Category Model:

class Category < ActiveRecord::Base 

    extend FriendlyId
    friendly_id :name, use: :slugged

    # Validations
    validates_uniqueness_of :name, :case_sensitive => false

end

Category Controller:

(generated by scaffold for test purposes)

class CategoriesController < ApplicationController
  before_action :set_category, only: [:show, :edit, :update, :destroy]

  # GET /categories
  # GET /categories.json
  def index
    @categories = Category.all
  end

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

  # GET /categories/new
  def new
    @category = Category.new
  end

  # GET /categories/1/edit
  def edit
  end

  # POST /categories
  # POST /categories.json
  def create
    @category = Category.new(category_params)

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

  # PATCH/PUT /categories/1
  # PATCH/PUT /categories/1.json
  def update
    respond_to do |format|
      if @category.update(category_params)
        format.html { redirect_to @category, notice: 'Category was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @category.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /categories/1
  # DELETE /categories/1.json
  def destroy
    @category.destroy
    respond_to do |format|
      format.html { redirect_to categories_url }
      format.json { head :no_content }
    end
  end

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

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

Migration:##

(I added friendlyId after create the Category table, but I think is okay)

class AddColumnToCategory < ActiveRecord::Migration
  def change
    add_column :categories, :slug, :string
    add_index :categories, :slug, unique: true
  end
end

Routes:

resources :categories

Hope you can help me. What I'm doing wrong in Rails 4.0?

Answer 1

Check the doc, friendly id stopped hacking find method (for the greater good), you now have to do:

# Change Category.find to Category.friendly.find in your controller
Category.friendly.find(params[:id])

Answer 2

You can now use:

extend FriendlyId friendly_id :name, use: [:finders]

in your model.