Ruby on Rails undefined method `title' for nil:NilClass -

i have following setup:

product.rb

class product < activerecord::base   belongs_to :category end 

category.rb

class category < activerecord::base   belongs_to :category   has_many :categories   has_many :products end 

categories_controller.rb

def show end  private   def set_category     @category = category.find(params[:id])   end    def category_params     params.require(:category).permit(:title, :category_id)   end 

products_controller.rb

def product_params    params.require(:product).permit(:title, :price, :text, :category_id, :avatar) end 

category show

<% @category.products.each |p| %>     <article class="content-block">       <h3><%= @p.title %></h3>    </article>  <% end %> 

and returns error in title. have done wrong here?

it should :

<h3><%= p.title %></h3> # as, block variable p, not @p 

not

<h3><%= @p.title %></h3> 

one more suggestion, write set_category method, as:

def set_category   @category = category.includes(:products).find(params[:id]) end 

it solve n + 1 problems using eager loading associations technique.