First argument in form cannot contain nil or be empty Hartl's Rails 4 Tutorial

12,396

Solution 1

In your new.html.erb you have specified form_for(@user) that means you need to have some value in instance variable @user before calling the new action.

You can do it in two ways :

one way is define an action new in your controller which would be called before rendering your new.html.erb layout. For eg:

def new
  @user = User.new
end

other way is that in your form itself you could specify something like

<%= form_for(User.new) do |f| %>

Defining it in your new action is more standard way of doing it.

Solution 2

The order of actions in controller file matters. I had the same error until I figure out the problem on order of action methods. Example. Controller file

def edit
  @post = Post.find(params[:id])
end

def update

end

private
def post_params
    params.require(:post).permit(:title, :body)
end

I was working on edit action and was getting same error as you. The problem was I have written the edit action under private action. once I changed the order of this actions. It worked like a charm.

What I was trying to achieve ? I was trying to take the values of post instance variable and use it into html form.

Share:
12,396
jovianlynxdroid
Author by

jovianlynxdroid

Updated on June 08, 2022

Comments

  • jovianlynxdroid
    jovianlynxdroid over 1 year

    I'm working through Michael Hartl's Rails tutorial, and I'm running into an issue in section 7.3.3. I receive this error message:

    ArgumentError in Users#new
    Showing /Users/Anuraag/rails_projects/sample_app/app/views/users/new.html.erb where line #6 raised:
    First argument in form cannot contain nil or be empty
    

    when I run the following rspec:

    bundle exec rspec spec/requests/user_pages_spec.rb -e "signup with invalid information"
    

    at the following line:

    <%= form_for(@user) do |f| %>
    

    Here is my code. Please also let me know how I should improve this question if I'm not framing it well: I'm pretty new to StackOverflow as well

    app/views/users/new.html.erb:

    <% provide(:title, 'Sign up') %>
    <h1>Sign up</h1>
    
    <div class="row">
      <div class="span6 offset3">
        <%= form_for(@user) do |f| %>
          <%= render 'shared/error_messages' %>
    
          <%= f.label :name %>
          <%= f.text_field :name %>
    
          <%= f.label :email %>
          <%= f.text_field :email %>
    
          <%= f.label :password %>
          <%= f.password_field :password %>
    
          <%= f.label :password_confirmation, "Confirmation" %>
          <%= f.password_field :password_confirmation %>
    
          <%= f.submit "Create my account", class: "btn btn-large btn-primary" %>
        <% end %>
      </div>
    </div>
    

    app/assets/controllers/users_controller.rb:

    class UsersController < ApplicationController
      def show
        @user = User.find(params[:id])
      end
    
      def create
        @user = User.new(user_params)
        if @user.save
          # Handle a successful save.
        else
          render 'new'
        end
      end
    
      private
    
        def user_params
          params.require(:user).permit(:name, :email, :password,
                                       :password_confirmation)
        end
    end
    

    spec/requests/user_pages_spec.rb

    require 'spec_helper'
    
    describe "User pages" do
    
      subject { page }
    
      describe "signup page" do
        before { visit signup_path }
    
        it { should have_content('Sign up') }
        it { should have_title(full_title('Sign up')) }
      end
    
      describe "profile page" do
        let(:user) { FactoryGirl.create(:user) }
        before { visit user_path(user) }
    
        it { should have_content(user.name) }
        it { should have_title(user.name) }
      end
    
      describe "signup" do
    
        before { visit signup_path }
    
        let(:submit) { "Create my account" }
    
        describe "with invalid information" do
          it "should not create a user" do
            expect { click_button submit }.not_to change(User, :count)
          end
        end
    
        describe "with valid information" do
          before do
            fill_in "Name",         with: "Example User"
            fill_in "Email",        with: "[email protected]"
            fill_in "Password",     with: "foobar"
            fill_in "Confirmation", with: "foobar"
          end
    
          it "should create a user" do
            expect { click_button submit }.to change(User, :count).by(1)
          end
        end
      end
    end