Rails 4 uninitialized constant Admin::Category

Question

I have generated Admin namespaced Controllers for all my default models as follows:

rails g scaffold_controller admin/categories name:string slug:string description:string icon_xlarge:string icon_large:string icon_medium:string icon_small:string status:integer

This generated the following files:

Harshas-MacBook-Pro:nomad harshamv$ rails g scaffold_controller admin/categories name:string slug:string description:string icon_xlarge:string icon_large:string icon_medium:string icon_small:string status:integer
Plural version of the model detected, using singularized version. Override with --force-plural.
      create  app/controllers/admin/categories_controller.rb
      invoke  erb
      create    app/views/admin/categories
      create    app/views/admin/categories/index.html.erb
      create    app/views/admin/categories/edit.html.erb
      create    app/views/admin/categories/show.html.erb
      create    app/views/admin/categories/new.html.erb
      create    app/views/admin/categories/_form.html.erb
      invoke  test_unit
      create    test/controllers/admin/categories_controller_test.rb

app/model/category.rb

class Category < ActiveRecord::Base

  extend FriendlyId

  friendly_id :name, use: :slugged

  has_and_belongs_to_many :venues

end

app/controller/admin/categories_controller.rb

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

  # GET /admin/categories
  def index
    @admin_categories = Admin::Category.all
  end

  # GET /admin/categories/1
  def show
  end

  # GET /admin/categories/new
  def new
    @admin_category = Admin::Category.new
  end

  # GET /admin/categories/1/edit
  def edit
  end

  # POST /admin/categories
  def create
    @admin_category = Admin::Category.new(admin_category_params)

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

  # PATCH/PUT /admin/categories/1
  def update
    if @admin_category.update(admin_category_params)
      redirect_to @admin_category, notice: 'Category was successfully updated.'
    else
      render :edit
    end
  end

  # DELETE /admin/categories/1
  def destroy
    @admin_category.destroy
    redirect_to admin_categories_url, notice: 'Category was successfully destroyed.'
  end

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

    # Only allow a trusted parameter "white list" through.
    def admin_category_params
      params.require(:admin_category).permit(:name, :slug, :description, :icon_xlarge, :icon_large, :icon_medium, :icon_small, :status)
    end
end

app/view/admin/categories/index.html.erb

<h1>Listing admin_categories</h1>

<table>
  <thead>
    <tr>
      <th>Name</th>
      <th>Slug</th>
      <th>Description</th>
      <th>Icon xlarge</th>
      <th>Icon large</th>
      <th>Icon medium</th>
      <th>Icon small</th>
      <th>Status</th>
      <th colspan="3"></th>
    </tr>
  </thead>

  <tbody>
    <% @admin_categories.each do |admin_category| %>
      <tr>
        <td><%= admin_category.name %></td>
        <td><%= admin_category.slug %></td>
        <td><%= admin_category.description %></td>
        <td><%= admin_category.icon_xlarge %></td>
        <td><%= admin_category.icon_large %></td>
        <td><%= admin_category.icon_medium %></td>
        <td><%= admin_category.icon_small %></td>
        <td><%= admin_category.status %></td>
        <td><%= link_to 'Show', admin_category %></td>
        <td><%= link_to 'Edit', edit_admin_category_path(admin_category) %></td>
        <td><%= link_to 'Destroy', admin_category, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<br>

<%= link_to 'New Category', new_admin_category_path %>

My Attempts

I edited the Controller as below

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

  # GET /admin/categories/1
  def show
  end

  # GET /admin/categories/new
  def new
    @admin_category = Category.new
  end

  # GET /admin/categories/1/edit
  def edit
  end

  # POST /admin/categories
  def create
    @admin_category = Category.new(admin_category_params)

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

When I go to localhost/admin/categories and click "NEW category", I get the following error now:

My routes file:

Rails.application.routes.draw do

  # Admin Routing
  namespace :admin do
    resources :categories, :cities, :countries, :lists, :oauths, :regions, :tags, :users, :user_groups, :venues, :venue_photos, :venue_reviews
  end

end

You have a namespace `admin`,so this line `<%= form_for(@admin_category) do |f| %>` should be `<%= form_for([:admin, @admin_category]) do |f| %>`. — Pavan, Jun 18 '14 at 18:31
Another issue - Is your model really under the Admin namespace? - it may be `Category.new` not `Admin::Category.new` — Mark Swardstrom, Jun 18 '14 at 18:35
@Pavan i edited form and i am getting another error now. http://i.imgur.com/w9OiJGw.jpg — Harsha M V, Jun 18 '14 at 18:37
@Swards yeah i tried to change that. guess rails generate doesnt automatically scaffold files correctly for namescopes :( — Harsha M V, Jun 18 '14 at 18:38
@HarshaMV With your second error.It should be just `params.require(:category).pemit(....)` — Pavan, Jun 18 '14 at 18:39

score 1 · Answer 1 · answered Jun 18 '14 at 18:35

1

To access models outside of the namespace you need to call ::Category.new instead of Admin::Category.new

answered Jun 18 '14 at 18:35

Arctodus

5,743
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with the prepended :: ? – Harsha M V Jun 18 '14 at 18:35
Correct. If `Category` were under the admin namespace you wouldnt even have to specify the namespace. You could just call `Category.new`. – Arctodus Jun 18 '14 at 18:48

Pavan · Accepted Answer · 2014-06-18T18:42:28.367

1

You have resources :categories defined under the namespace :admin in your routes.rb,so this line in your views/admins/categories/_form.html.erb

<%= form_for(@admin_category) do |f| %>

should be

<%= form_for([:admin, @admin_category]) do |f| %>

For more info,refer this API

Update

The second error is because of this line

params.require(:admin_category).permit(:name, :slug, :description, :icon_xlarge, :icon_large, :icon_medium, :icon_small, :status)

It should be

params.require(:category).permit(:name, :slug, :description, :icon_xlarge, :icon_large, :icon_medium, :icon_small, :status)

edited Jun 18 '14 at 18:42

answered Jun 18 '14 at 18:36

Pavan

33,316
7
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am using namescope for the first time and its pretty confusing even after reading through the document. I change params.require(:category).pemit(....) and ended up with this error :( http://i.imgur.com/Faa3dIS.jpg – Harsha M V Jun 18 '14 at 18:42
@Harsha MV What happens when you change this line `redirect_to @admin_category` to `redirect_to admin_categories_url` in your `create action`? – Pavan Jun 18 '14 at 19:04
You can also try `redirect_to admin_category_path(@admin_category)` The scaffold generator expected the Category model to be namespaced, that's why you need to adjust a few things. – Arctodus Jun 18 '14 at 19:05
damn looks like i can just write my controllers manually its easier :( Both dont seem to work. same error – Harsha M V Jun 18 '14 at 19:12
@HarshaMV Good luck with that.Good night :) – Pavan Jun 18 '14 at 19:13
@Pavan hehe :D thanks buddy :D i will get back if i find any issues :( – Harsha M V Jun 18 '14 at 19:16
thanks guys. simplified the routes and variables and seem to be working :D – Harsha M V Jun 19 '14 at 06:07

steel · Answer 3 · 2014-06-18T18:44:30.810

1

As your error indicates, this is an issue with how you are calling your form. Your form needs to reference the admin namespace, like this:

<%= form_for [:admin, @category] do |f| %>

However, there are a number of things different about the way the scaffold built your docs from how I would recommend.

I would also suggest simplifying the code in the scaffolded controller to reference simple @category and @categories, rather than @admin_category and @admin_categories.

Also, the model should not be in the admin namespace, so Admin::Category.new should be Category.new. The rest of the model calls should be adjusted accordingly as well.

edited Jun 18 '14 at 18:44

answered Jun 18 '14 at 18:37

steel

11,883
7
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1

Try heading into your controller file and changing require(:admin_category) to require(:category). – steel Jun 18 '14 at 18:40
are these error because am using the model outside the namescope? i am trying to simply it. http://i.imgur.com/Faa3dIS.jpg – Harsha M V Jun 18 '14 at 18:45
You'll just need to do some more editing to clear this up. To fix the most recent issue, try redirect_to admin_category_path(@category), if you're using my variable name suggestions. – steel Jun 18 '14 at 18:47
If you're still getting weird errors losing patience, maybe take a breather and work through this tutorial: http://everydayrails.com/2012/07/31/rails-admin-panel-from-scratch.html – steel Jun 18 '14 at 18:51
freak :D i think i need a breather big time. thanks a lot for the link i will check it out :D – Harsha M V Jun 18 '14 at 18:54

Rails 4 uninitialized constant Admin::Category

My Attempts

3 Answers3