Initially built with scaffold, edit and show links were working. After working extensively on index (ajaz, paging, sorting, search fielkds, partials), I have discovered they are no longer working! For example the show.html.erb gives me: undefined method `name' for nil:NilClass when executing <%= @game_class.name % However, the show method is def…

_game_classes.html.erb

<%= hidden_field_tag :direction, params[:direction] %>
<%= hidden_field_tag :sort, params[:sort] %>
<table class="pretty">
<thead>
  <tr>
    <th><%= sortable "name" %></th>
    <th>Description</th>
    <th><%= sortable "game_id" %></th>
    <th></th>
    <th></th>
    <th></th>
    </tr>
</thead>


<% for game_class in @game_classes %>	
  <tr>
    <td><%= game_class.name %></td>
    <td><%= game_class.description %></td>
    <td><%= game_class.game_id %></td>
    <td><%= link_to 'Show', game_class %></td>
    <td><%= link_to 'Edit', edit_game_class_path(game_class) %></td>
    <td><%= link_to 'Destroy', game_class, method: :delete, data: { confirm: 'Are you sure?' } %></td>
  </tr>
<% end %>
</table>


<div id="paginator">
	<%= paginate @game_classes %>
</div> 	

game_classes_controller.rb

class GameClassesController < ApplicationController
  # GET /game_classes
  # GET /game_classes.json
  
  # added to allow controller to generate parameters if not present. railscast 228
  helper_method :sort_column, :sort_direction 
  
  def index
    
    @game_classes = GameClass.search(params[:search]).order(sort_column + ' ' + sort_direction).page(params[:page]).per(5)
    

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @game_classes }
      format.js # index.js.erb 
    end
  end
  
  # Methods to set sort peramiters securely (checking whats in the query string)
  private
  def sort_column
    GameClass.column_names.include?(params[:sort]) ? params[:sort] : "name"
  end
  
  def sort_direction
     %w[asc desc].include?(params[:direction]) ?  params[:direction] : "asc"
  end
  
  # GET /game_classes/1
  # GET /game_classes/1.json
  def show
    @game_class = GameClass.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @game_class }
    end
  end

  # GET /game_classes/new
  # GET /game_classes/new.json
  def new
    @game_class = GameClass.new

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @game_class }
    end
  end

  # GET /game_classes/1/edit
  def edit
    @game_class = GameClass.find(params[:id])
  end

  # POST /game_classes
  # POST /game_classes.json
  def create
    @game_class = GameClass.new(params[:game_class])

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

  # PUT /game_classes/1
  # PUT /game_classes/1.json
  def update
    @game_class = GameClass.find(params[:id])

    respond_to do |format|
      if @game_class.update_attributes(params[:game_class])
        format.html { redirect_to @game_class, notice: 'Game class was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @game_class.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /game_classes/1
  # DELETE /game_classes/1.json
  def destroy
    @game_class = GameClass.find(params[:id])
    @game_class.destroy

    respond_to do |format|
      format.html { redirect_to game_classes_url }
      format.json { head :no_content }
    end
  end
  
  
end

index.html.erb

<h1>Listing game_classes</h1>

<%= form_tag game_classes_path, :method => 'get', :id => "game_classes_search" do %>
  <p>
    <%= text_field_tag :search, params[:search] %>
    <%= submit_tag "Search", :name => nil %>

  </p>
  
<div id="game_classes"><%= render 'game_class' %></div>

<%-end %>

<p><%= link_to "New Class", new_game_class_path %></p>

show.html.erb

<p id="notice"><%= notice %></p>

<p>
  <b>Name:</b>
  <%= @game_class.name %>
</p>

<p>
  <b>Description:</b>
  <%= @game_class.description %>
</p>


<%= link_to 'Edit', edit_game_class_path(@game_class) %> |
<%= link_to 'Back', game_classes_path %>

An example error url: http://localhost:3000/game_classes/13

Error: undefined method `name' for nil:NilClass

code generating the error:

4: Name:
5: <%= @game_class.name %>

Parameters:

{"id"=>"13"}