Polymorpic paperclip working strange with Rails 5 - ruby-on-rails

Question

view:
<div class="kitchen_settings">
<%= form_for #kitchen, :html => { :multipart => true, "data-ajax" => false} do |f| %>
<%= f.text_field :title,placeholder: "#{current_user.fullname}'s Kitchen", autofocus: true %>
<%= f.text_field :bio, placeholder: 'something about your kitchen' %>
<%= f.fields_for :picture do |photo| %>
<%= photo.file_field :avatar %>
<% end %>
<%= f.submit %>
<% end %>
kitchen_controller.rb
class KitchensController < ApplicationController
before_action :authenticate_user!
def new
#kitchen = Kitchen.new
#kitchen.build_picture
end
def create
#kitchen = current_user.build_kitchen(kitchen_params)
respond_to do |format|
if #kitchen.save
format.html { redirect_to dashboard_path, notice: 'Kitchen was successfully created.' }
format.json { render :show, status: :created, location: dashboard_path }
else
format.html { render :new }
format.json { render json: #kitchen.errors, status: :unprocessable_entity }
end
end
end
def show
#kitchen = Kitchen.find (params[:id])
end
private
def kitchen_params
params.require(:kitchen).permit(:title,:bio, picture_attributes: [:avatar])
end
end
kitchen.rb
class Kitchen < ApplicationRecord
belongs_to :user
has_one :picture, as: :imageable, dependent: :destroy
accepts_nested_attributes_for :picture
end
picture.rb
class Picture < ApplicationRecord
belongs_to :imageable, polymorphic: true
has_attached_file :avatar, styles: { medium: "300x300>", thumb: "100x100"}, default_url: "/assets/:style/missing.png"
validates_attachment :avatar, :presence => true,
:content_type => { :content_type => ["image/jpeg", "image/gif", "image/png"] },
:size => { :in => 0..500.kilobytes }
end
And its giving me this error
I wanted polymorphic picture model. I decided to deal with polymorphic picture association but its just rollbacks always... Stuck. I've attached the image from the console. Thanks!!
Debugged it using binding.pry

Answer 1

In Rails 5, whenever we define a belongs_to association, it is required to have the associated record present by default after this change.To change this behavior i managed to do it this way:
picture.rb
class Picture < ApplicationRecord
belongs_to :imageable, polymorphic: true, optional: true
has_attached_file :avatar, styles: { medium: "300x300>", thumb: "100x100"}, default_url: "/assets/:style/missing.png"
validates_attachment :avatar, :presence => true,
:content_type => { :content_type => ["image/jpeg", "image/gif", "image/png"] },
:size => { :in => 0..500.kilobytes }
end

Answer 2

There is a problem with you validation of imageable in image.rb
When you store kitchen alongwith image in single go. Imageable validation is failed for image as kitchen is not created yet. That's why it's rollback.
To confirm it you can remove the validation temporarily.
You need to use inverse_of to make this work
in image.rb
belongs_to :imageable, polymorphic: true , inverse_of: :image
in kitchen.rb
has_one :picture, as: :imageable, dependent: :destroy,inverse_of: :imageable
I added inverse_of in both the associations. It tells rails that these associations are inverse to each other so if any of it's set then don't make a query to fetch the other.
In this way if you set any association then other will be set automatically and validation won't fail.
Here is a nice blog for inverse_of usage.