Undefined Method in Picture Controller -

warning, i'm newb , trying learn ror on own. been doing tutorials etc , trying learn through experience. long story short i'm trying attach user picture url defined them, default pic if don't supply one. been running kinds of errors, think have down 1 primary issue after hours of trying figure out (since i'm new @ this). right error i'm getting is:

nomethoderror in gravscontroller#update undefined method `update_attributes' nil:nilclass 

i know means need like:

@something = model.new/build(params[:method]) 

but don't know define in controller (i'm guessing gravs_controller right?) here's code, tear apart , see if can me image function working, please :)

class gravscontroller < applicationcontroller before_filter :signed_in_user 

gravs_controller

def create     @graver = current_user.gravs.new(params[:content])     @grav_bool = false         if @graver.save             @grav_bool = true             @grav_bool.save             flash[:success] = "user picture saved!"             redirect_to faq_path         else             @grav_bool = false             @grav_bool.save             redirect_to faq_path         end end   def update      if @graver.update_attributes(params[:content])         @grav_bool = true         @grav_bool.save         flash[:success] = "user picture saved!"         redirect_to faq_path     else         @grav_bool = false         @grav_bool.save         redirect_to faq_path     end   end end 

users_controller

class userscontroller < applicationcontroller  before_filter :signed_in_user, only: [:index, :edit, :update, :destroy, :gravs] before_filter :correct_user, only: [:edit, :update, :gravs] before_filter :admin_user, only: :destroy  def index     @users = user.paginate(page: params[:page]) end  def show     @user = user.find(params[:id])     @microposts = @user.microposts.paginate(page: params[:page]) end  def new @user = user.new end   def create     @user = user.new(params[:user])     if @user.save         sign_in @user         flash[:success] = "welcome inception!"         redirect_to gravs_path     else         render 'new'     end end   def edit end  def update     if @user.update_attributes(params[:user])         sign_in @user         flash[:success] = "profile updated"         redirect_to gravsid_path     else         render 'edit'     end end      def destroy         user.find(params[:id]).destroy         flash[:success] = "user deleted"         redirect_to users_path     end  private  def correct_user     @user = user.find(params[:id])     redirect_to (root_path), error: "cannot edit others information!" unless current_user?(@user) end  def admin_user     redirect_to(root_path) unless current_user.admin? end end 

create.html.erb (inside /views/gravs/)

<% provide(:title, "edit picture") %> <div class="barney">     <div class="trouble"> <h1>update picture</h1>      <%= gravs_display @graver %>         <%= form_for(:grav) |f| %>             <div class="field">             <%= f.text_field :content, placeholder: "enter picture url" %>             </div>             <%= f.submit "update user image", class: "btn btn-small btn-primary" %>         <% end %>     </div> </div> 

update.html.erb (inside /views/gravs/)

<% provide(:title, "edit picture") %> <div class="barney">     <div class="trouble">         <div class="row">             <div class="span6 offset3">                 <h1>update picture</h1>                  <%= gravs_display @graver %>                  <%= form_for(:gravs) |f| %>                     <div class="field">                         <%= f.text_field :content, placeholder: "update picture url" %>                     </div>                     <%= f.submit "update user image", class: "btn btn-small btn-primary" %>                 <% end %>             </div>         </div>     </div> </div> 

** datenumber_create_gravs.rb**

class creategravs < activerecord::migration def change create_table :gravs |t|   t.string :content   t.integer :user_id end end end 

schema.rb

activerecord::schema.define(:version => 20130407202835)  create_table "gravs", :force => true |t|   t.string  "content"   t.integer "user_id" end  create_table "microposts", :force => true |t|   t.string   "content"   t.integer  "user_id"   t.datetime "created_at", :null => false   t.datetime "updated_at", :null => false end  add_index "microposts", ["user_id", "created_at"], :name => "index_microposts_on_user_id_and_created_at"  create_table "users", :force => true |t|   t.string   "name"   t.string   "email"   t.datetime "created_at",                         :null => false   t.datetime "updated_at",                         :null => false   t.string   "password_digest"   t.string   "remember_token"   t.boolean  "admin",           :default => false end  add_index "users", ["email"], :name => "index_users_on_email", :unique => true add_index "users", ["remember_token"], :name => "index_users_on_remember_token"  end 

routes.rb

mydeasample::application.routes.draw resources :users resources :sessions, only: [:new, :create, :destroy] resources :microposts, only: [:create, :destroy]  root to: "static_pages#home" match '/help', to: 'static_pages#help' match '/about', to: 'static_pages#about' match '/contact', to: 'static_pages#contact' match '/signup', to: 'users#new' match '/signin', to: 'sessions#new' match '/signout', to: 'sessions#destroy', via: :delete match '/message', to: 'static_pages#message' match '/faq', to: 'static_pages#faq' match '/gravs', to: 'gravs#create' match '/gravsid', to: 'gravs#update'