Couldn't find User without an ID in form object - ruby-on-rails

Question

Could you help me? I got an error Couldn't find User without an ID, I was thinking about make like a blog service, I wanted to implement nest attribute without accepts_nested_attributes_for, so I've been using
form object, but I couldn't send form object user's parameter,
controller
class BlogsController < ApplicationController
before_action :authenticate_user!
def index
#current = current_user
end
def new
#blogs = BlogForm.new
end
def create
#blogs = BlogForm.new(blog_params)
if #blogs.save
redirect_to user_blogs_path
else
end
end
def edit
end
def show
end
private
def blog_params
params.require(:blog_form).permit(:title , :content , :user_id)
end
end
form html
<%= form_with model: #blogs , url: user_blogs_path,local: true do |f| %>
<% f.label :title %>
<%= f.text_field :title %>
<% f.label :content %>
<%= f.text_area :content %>
<% f.label :user_id %>
<% f.hidden_field :user_id , value: current_user.id%>
<%= f.submit "create", class: "btn btn-primary" %>
<% end %>
blog_form
class BlogForm
include ActiveModel::Model
attr_accessor :title, :content, :user_id
def to_model
#user = User.find(user_id)
#blogs = #user.blogs.new(title: title , content: content , user_id: user_id)
end
def save
return false if invalid
to_model.save
end
end
blogs.rb
class Blog < ApplicationRecord
belongs_to :user
validates :title ,presence: true
validates :content ,presence: true
end
user.rb
class User < ApplicationRecord
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :validatable
has_many :blogs
def email_required?
false
end
def email_changed?
false
end
def will_save_change_to_email?
false
end
end
log
ActionView::Template::Error (Couldn't find User without an ID):
1: <%= form_with model: #blogs , url: user_blogs_path,local: true do |f| %>
2:
3: <% f.label :title %>
4: <%= f.text_field :title %>
app/forms/blog_form.rb:6:in `to_model'
app/views/blogs/shared/_form.html.erb:1
app/views/blogs/new.html.erb:4
Started GET "/users/1/blogs/new" for 127.0.0.1 at 2020-01-19 16:29:03 +0900
Processing by BlogsController#new as HTML
Parameters: {"user_id"=>"1"}
Rendering blogs/new.html.erb within layouts/application
Rendered blogs/shared/_form.html.erb (Duration: 3.0ms | Allocations: 1143)
Rendered blogs/new.html.erb within layouts/application (Duration: 10.5ms | Allocations: 1228)
Completed 500 Internal Server Error in 16ms (ActiveRecord: 0.0ms | Allocations: 1715)
ActionView::Template::Error (Couldn't find User without an ID):
1: <%= form_with model: #blogs , url: user_blogs_path,local: true do |f| %>
2:
3: <% f.label :title %>
4: <%= f.text_field :title %>
app/forms/blog_form.rb:6:in `to_model'
app/views/blogs/shared/_form.html.erb:1
app/views/blogs/new.html.erb:4
after, I tried coreyward's way, but I couldn't,
rocessing by BlogsController#new as HTML
Parameters: {"user_id"=>"1"}
User Load (0.4ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? ORDER BY "users"."id" ASC LIMIT ? [["id", 1], ["LIMIT", 1]]
Rendering blogs/new.html.erb within layouts/application
Rendered blogs/shared/_form.html.erb (Duration: 6.9ms | Allocations: 1082)
Rendered blogs/new.html.erb within layouts/application (Duration: 9.4ms | Allocations: 1166)
Completed 500 Internal Server Error in 114ms (ActiveRecord: 2.3ms | Allocations: 11134)
ActionView::Template::Error (Couldn't find User without an ID):
1: <%= form_with model: #blogs , url: user_blogs_path(#user),local: true do |f| %>
2:
3: <% f.label :title %>
4: <%= f.text_field :title %>
app/forms/blog_form.rb:6:in `to_model'
app/views/blogs/shared/_form.html.erb:1
app/views/blogs/new.html.erb:4

Answer 1

The route helper user_blogs_path probably expects an argument for the user. Something like this:
user_blogs_path(#user)
Which goes in this line:
<%= form_with model: #blogs , url: user_blogs_path(#user),local: true do |f| %>

Answer 2

This is just a really strange and awkward way of doing a nested resource. This really has very little to do with nested attributes which used when you need to create or update two (or more) associated records in the same request.
# routes.rb
resources :users do
resources :blogs,
only: [:new, :show, :create],
shallow: true
end
class BlogsController
before_action :set_user, only: [:new, :create]
# GET /blogs/1
def show
#blog = Blog.find(params[:id])
end
# GET /users/1/blogs/new
def new
#blogs = #user.blog.new
end
# POST /users/1/blogs
def create
#blogs = #user.blog.new(blog_params)
if #blog.save
redirect_to #blog
else
render :new
end
end
private
def set_user
#user = User.find(params[:user_id])
end
def blog_params
params.require(:blog).permit(:title, :content)
end
end
<%= form_with model: [#user, #blog], local: true do |f| %>
<% f.label :title %>
<%= f.text_field :title %>
<% f.label :content %>
<%= f.text_area :content %>
<%= f.submit "create", class: "btn btn-primary" %>
<% end %>