rails: nested resources saving empty records - ruby-on-rails

Question

I have created a simple form of nested resources. I can't get the child form todo_item to save correctly. When I click the "create todo item" button, an empty record will be created and saved no matter what I put in the title field.
The code is really simple and the parent record is saving fine. the child records are displaying so I can't figure out what could be wrong. Please help.
My models:
class TodoItem < ActiveRecord::Base
belongs_to :todo_list
end
class TodoList < ActiveRecord::Base
has_many :todo_items, dependent: :destroy
end
My controllers:
class TodoItemsController < ApplicationController
before_action :set_todo_list
before_action :set_todo_item, only: [:show, :edit, :update, :destroy]
def new
#todo_item = #todo_list.todo_items.new
end
def create
#todo_item = #todo_list.todo_items.new
respond_to do |format|
if #todo_list.save
format.html { redirect_to #todo_list, notice: 'Todo item was successfully created.' }
format.json { render :show, status: :created, location: #todo_list }
else
format.html { render :new }
format.json { render json: #todo_list.errors, status: :unprocessable_entity }
end
end
end
private
def set_todo_item
#todo_item = #todo_list.todo_items.find(params[:id])
end
def set_todo_list
#todo_list = TodoList.find(params[:todo_list_id])
end
def todo_item_params
params.require(:todo_item).permit(:title, :due_date, :description, :text, :completed)
end
end
View.html.erb:
<h1>New Todo Item</h1>
<%= render 'form' %>
<%= link_to 'Back', #todo_list %>
_form.html.erb:
<%= form_for([#todo_list, #todo_item]) do |f| %>
...
<div class="field">
<%= f.label :title %><br>
<%= f.text_field :title %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>

Answer 1

You initialize the #todo_item here:
def create
#todo_item = #todo_list.todo_items.new # <===== INITIALIZED HERE
respond_to do |format|
if #todo_list.save # <===== SAVED HERE WITHOUT EVER ASSIGNING VALUES.
format.html { redirect_to #todo_list, notice: 'Todo item was successfully created.' }
format.json { render :show, status: :created, location: #todo_list }
else
format.html { render :new }
format.json { render json: #todo_list.errors, status: :unprocessable_entity }
end
end
end
But, don't provide any arguments to new. So, the new record has no values.
Instead, do something more like:
#todo_item = #todo_list.todo_items.new(todo_item_params)
Perhaps you should also add some validations so you could avoid this situation.

Answer 2

You need to modify the create method:
def create
#todo_item = #todo_list.todo_items.create(todo_item_params)
respond_to do |format|
if #todo_list.save
format.html { redirect_to #todo_list, notice: 'Todo item was successfully created.' }
format.json { render :show, status: :created, location: #todo_list }
else
format.html { render :new }
format.json { render json: #todo_list.errors, status: :unprocessable_entity }
end
end
end