"Actioncontroller::Parametermissing" error, even with form sending parameters

Question

I’m probably letting something really stupid go through, but I’ve been trying to find the solution for hours and nothing.

I am creating a CRUD of games. My problem is happening in the action games#create of my controller games.

Here is my implementation:

Controller "Games" (app/controllers/games_controller.Rb)

class GamesController < ApplicationController

    def index
        @games = Game.all
    end

    def show
        @game = Game.find(params[:id])
        @stories = @game.stories
    end

    def new
        @game = Game.new
    end

    def create
        @game = Game.new(game_params)
        if @game.save
            redirect_to '/'
        else
            render 'new'
        end
    end

    private
    def game_params
        params.require(:title).permit(:logo, :start_screen_bg, :start_screen_bgm)
    end

end

I’m trying to carry out the action create through a form in the view new of that controller.

Game controller view "new" (app/views/games/new.html.erb)

<h1>Create New Game</h1>

<%= form_for (@game) do |g|%>
    <%= g.text_field :title %></br>
    <%= g.text_field :logo, :placeholder => "Logo URL" %></br>
    <%= g.text_field :start_screen_bg, :placeholder => "start screen bg" %></br>
    <%= g.text_field :start_screen_bgm, :placeholder => "start screen bgm" %></br>
    <%= g.submit "Create" %>
<% end %>

When I give Submit, the following error occurs:

ActionController::ParameterMissing in GamesController#create
param is missing or the value is empty: title
Extracted source (around line #27):
25
26
27
28
29
30

    private
    def game_params
        params.require(:title).permit(:logo, :start_screen_bg, :start_screen_bgm)
    end

end

Rails.root: E:/Projetos/

Application Trace | Framework Trace | Full Trace
app/controllers/games_controller.rb:27:in `game_params'
app/controllers/games_controller.rb:17:in `create'
Request
Parameters:

{"utf8"=>"✓",
 "authenticity_token"=>"3fMm6sbdqrgaYZIapN3jHb0Tq0AhslKcrVze1LWLMWpNhm2usUPCh8UXKTBg1Kzpt2Lrq5EGr+egyFxeUGuzwg==",
 "game"=>
  {"title"=>"A New Game",
   "logo"=>"https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png",
   "start_screen_bg"=>"https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png",
   "start_screen_bgm"=>"https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_272x92dp.png"},
 "commit"=>"Create"}

As you can see by the "Parameters" section, the required parameter :title is being sent.

I tested comment on the line params.require(:title).permit(:logo, :start_screen_bg, :start_screen_bgm). The record is successfully created, but empty.

I feel like it’s something very simple that I’m missing...

Has anyone experienced a similar problem? Can you help me?

Hugs!

Answer 1

Bruno, that call params require permit is called Strong Parameters.

In the first part, you must reference the class name.
change of params.require(:title) for params.require(:game)

in the second part you must put the attributes.
add the title here, as shown below.

permit(:logo, :start_screen_bg, :start_screen_bgm, :title)

At the end you must have something like this

params.require(:game).permit(:logo, :start_screen_bg, :start_screen_bgm, :title)

Tip
require o Modelo (:game)
permit the attributes of the model

How you say the title attribute is being sent. Correct. Your page sends the title template.
However, your controller is not allowing it correctly.