Empty item displaying from nested resource - ruby-on-rails

Question

I'm new to Rails and am building a todo app.
For some reason an empty Item instance is displaying within all lists by default. Item.count is returning 0, but <%= render #list.items %> always has one "instance" of _item.html.erb.
I have #list assigned to List.find(params[:id]) in the list controller's show method and am calling <%= render #list.items %> in its show view.
I have this link in _item.html.erb
<%= link_to "Delete", [item.list, item],
method: :delete,
data: { confirm: "Are you sure?" }
%>
and it will display the delete link, but link to lists/*/items (as opposed to list/*/items/*) in the empty item, which gives a routing error. The link works fine in actual items though.
Controllers:
lists_controller.rb:
class ListsController < ApplicationController
before_action :set_list, only: [:show, :edit, :update, :destroy]
def index
#lists = policy_scope(List).where(author: current_user)
end
def show
#item = #list.items.build
end
def new
#list = List.new
authorize #list
end
def create
#list = List.new(list_params)
#list.author = current_user
authorize #list
if #list.save
flash[:notice] = "Your list was created."
redirect_to #list
else
flash[:error] = "Your list was not created."
render "new"
end
end
def edit
end
def update
if #list.update(list_params)
flash[:notice] = "Your list was updated."
redirect_to #list
else
flash[:error] = "Your list was not updated."
render "edit"
end
end
def destroy
if #list.destroy
flash[:notice] = "Your list was deleted."
redirect_to root_path
else
flash[:error] = "Your list was not deleted."
redirect_to #list
end
end
private
def list_params
params.require(:list).permit(:title, :description, :author_id)
end
def set_list
#list = List.find(params[:id])
authorize #list
end
end
items_controller.rb:
class ItemsController < ApplicationController
before_action :set_list
def create
#item = #list.items.create(item_params)
authorize #item
if #item.save
flash[:notice] = "Your item was added."
redirect_to #list
else
flash.now[:error] = "Your item was not added."
end
end
def destroy
#item = #list.items.find(params[:id])
authorize #item
if #item.destroy
flash[:notice] = "Your item was deleted."
redirect_to #list
else
flash.now[:error] = "Your item was not deleted."
end
end
private
def item_params
params.require(:item).permit(:name, :list_id)
end
def set_list
#list = List.find(params[:list_id])
end
end
Models:
list.rb:
class List < ActiveRecord::Base
validates :title, presence: true
validates :description, presence: true
belongs_to :author, class_name: "User"
has_many :items, dependent: :destroy
end
item.rb:
class Item < ActiveRecord::Base
validates :name, presence: true
belongs_to :list
end
Routes:
Rails.application.routes.draw do
root "lists#index"
resources :lists do
resources :items
end
devise_for :users
end
Reference migration:
class AddListsToItems < ActiveRecord::Migration
def change
add_reference :items, :list, index: true, foreign_key: true
end
end

Answer 1

The issue was caused by the way I passed the instance variable to the form.
This line in ListsController is building a new item on each page refresh.
def show
#item = #list.items.build
end
I removed that assignment, as well as its passing to the form.
<%= render "items/form", list: #list, item: #item %> becomes <%= render "items/form", list: #list %>
simple_form_for([list, item] becomes simple_form_for([#list, #list.items.build]

Answer 2

#item = #list.items.build is your problem.
The issue is that building a nested item will always yield an "empty" item, especially if it's nested.
Whilst you can use the code in the new action with impunity, using in show will basically just create a blank object that you have to contend with.
--
If you want to create a new item object when viewing your #list, you'll be better building / invoking on the fly (as you're doing already):
<%= form_for [#list, #list.items.new] ...

Answer 3

try
<%= render 'item' %>
and on your _item.html.erb (which is rendered), use the following code:
<%= #list.items %>