ruby on rails - Adding an object to one to many relationship ROR -

i having trouble adding object associate class. parent class, user, has has_many relation ad class. when try access user's has_many object ":ads" ad controller, returns me "undefined method ads" exception. posting model , controller code below. please me on issue.

user model

class user < activerecord::base      has_many :ads      has_secure_password      has_attached_file :avatar, :styles => { :medium => "300x300>", :thumb => "50x50#" }, :default_url => "/images/:style/missing.png"     validates_attachment_content_type :avatar, :content_type => /\aimage\/.*\z/      def self.searchid(query)         where("id ?", "#{query}")      end end 

ad model

class ad < activerecord::base      belongs_to :user      scope :ordernewestfirst , lambda { order("id desc") }      has_attached_file :avatar, :styles => { :medium => "300x300>", :thumb => "100x100#" }, :default_url => "/images/:style/missing.png"     validates_attachment_content_type :avatar, :content_type => /\aimage\/.*\z/      def self.search(query)         where("title ?", "%#{query}%")      end  end 

ad controller

class adcontroller < applicationcontroller      layout false   before_action :confirm_logged_in      def index         @ads = ad.ordernewestfirst     end      def new         @ad = ad.new()     end      def create       @find = session[:user_id]       @user = user.searchid(@find)          @ad = ad.new(ad_params)          if @user.ads << @ad    #***this error occuring***             flash[:notice] = "ad created successfully"             redirect_to(:controller => 'user' , :action => 'index')         else             render('new')         end     end      def show         @ad = ad.find(params[:id])     end      def ad_params       params.require(:ad).permit(:title, :category, :description , :pricerange, :avatar )     end end 

edit

here migrations user , ad

user migration

class createusers < activerecord::migration      def         create_table :users |t|             t.string "firstname" , :limit => 50 , :null => false             t.string "lastname" , :limit => 50             t.string "email" , :null => false             t.string "password" , :limit => 30 , :null => false             t.integer "rating" , :default => 0             t.string "location" , :default => "lahore"             t.timestamps null: false         end     end      def down         drop_table :users     end end  #user = user.new(:firstname => "" , :lastname => "" , :email => "" , :password => "" , :rating => "" , :location => "") 

ad migration

class createads < activerecord::migration     def         create_table :ads |t|         t.references :user             t.string "title" , :null => false             t.string "category" , :null => false             t.text "description"              t.string "pricerange" , :null => false         t.attachment :avatar         t.timestamps null: false         end       add_index("ads" , "user_id")     end      def down         drop_table :ads     end  end   #ad = ad.new(:title => "" , :category => "" , :description => "" , :pricerange => "") 

the error get..

your user.searchid(query) returns multiple user records (a relation object), not single one.

if change user.searchid(query).take, fetches single record, , error vanishes.

i don't know value session[:user_id] holds, looking @ users table, integer id? in case, there isn't sense in current approach. i'd recommend this:

def create   @user = user.find(session[:user_id])    # rest of create method end 

the user.find method looks user record exact id, , return single record straight away. 1 of common ways fetch records using ruby on rails.