nil：NilClass rails 4.2的未定义方法“ update”

Question

I know there are other similar questions to this one but they don't work for me. This one is very similar but I don't see how the answer code is any different from the question.

Here is my error message

NoMethodError in UsersController#update
undefined method `update' for nil:NilClass
  def update
respond_to do |format|
  if @recipe.update(user_params)
    format.html { redirect_to @user, notice: 'User was successfully updated.' }
    format.json { render :show, status: :ok, location: @user }
  else

Here is my controller

 class UsersController < ApplicationController before_action :set_user, only: [:edit, :update] def new @user = User.new end def create @user = User.new(user_params) if @user.save redirect_to root_url, :notice => "Signed up!" else render "new" end end def edit end # PATCH/PUT /users/1 # PATCH/PUT /users/1.json def update respond_to do |format| if @recipe.update(user_params) format.html { redirect_to @user, notice: 'User was successfully updated.' } format.json { render :show, status: :ok, location: @user } else format.html { render :edit } format.json { render json: @user.errors, status: :unprocessable_entity } end end end private # Use callbacks to share common setup or constraints between actions. def set_user @user = User.find(params[:id]) end # Never trust parameters from the scary internet, only allow the white list through. def user_params params.require(:user).permit(:id, :name, :email, :password, :password_confirmation, :avatar) end end 

server log errors

 Started GET "/users/1/edit" for 127.0.0.1 at 2014-12-27 11:42:26 -0600 Processing by UsersController#edit as HTML Parameters: {"id"=>"1"} User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1 [["id", 1]] Rendered users/_form.html.erb (2.2ms) Rendered users/edit.html.erb within layouts/application (3.4ms) User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1 [["id", 1]] Completed 200 OK in 247ms (Views: 245.9ms | ActiveRecord: 0.6ms) Started PATCH "/users/1" for 127.0.0.1 at 2014-12-27 11:42:39 -0600 Processing by UsersController#update as HTML Parameters: {"utf8"=>"✓", "authenticity_token"=>"NIo0M4TntTzi4TDTsu+dWsSVHfnSnYFbW0Beew1YrApuebRNY9aadcI3/TzSsVN1Lc3R0iWbPGcxfjdW1Ovg4A==", "user"=>{"name"=>"Nathan Davis", "email"=>"NathanTheGreat94@gmail.com", "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]", "avatar"=>#<ActionDispatch::Http::UploadedFile:0x007f819c31d790 @tempfile=#<Tempfile:/var/folders/09/vs8567nx49v9mzhv7r6dyxrh0000gn/T/RackMultipart20141227-50092-j9p25d.jpg>, @original_filename="formal.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\\"user[avatar]\\"; filename=\\"formal.jpg\\"\\r\\nContent-Type: image/jpeg\\r\\n">}, "commit"=>"Update User", "id"=>"1"} User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1 [["id", 1]] Completed 500 Internal Server Error in 2ms NoMethodError (undefined method `update' for nil:NilClass): app/controllers/users_controller.rb:25:in `block in update' app/controllers/users_controller.rb:24:in `update' 

thanks for any help!

Answer 1

You have to allow the id param for your recipe. Because you haven't allowed it, the following returns nil

@recipe = Recipe.find(params[:id])

So change your recipe_params method to this:

params.require(:recipe).permit(:id, :name, :author, :body, :picture)

Update:

I see that you've updated your code but that the @recipe variable isn't being set in any before_action. If this is the case, then you need to check which param is for the recipe's ID and then do the following anywhere before you actually update the recipe:

@recipe = Recipe.find(whatever_is_the_param_for_recipe_id)

And if this is the user controller, you shouldn't be doing @recipe.update(user_params) . You most likely meant @user.update(user_params)