Nested Attribute not Saved in Database (Rails 5.1)

Question

I have two models, Countries and Regions. I'm trying to set regions to be a nested attribute of countries. My code so far writes the country to the database, but it does not write the region. I get no errors.

One other thing I'm unsure of in terms of the relationship, should a user be adding a region with country nested, or the other way round with a user adding a country with the region nested?

country.rb

class Country < ApplicationRecord
  has_many :regions, inverse_of: :country
  has_many :roasts
  accepts_nested_attributes_for :regions

  validates :name, presence: true
end

region.rb

class Region < ApplicationRecord
  belongs_to :country, inverse_of: :region

  validates :name, uniqueness: true
  validates :name, presence: true
end

country_controller.rb

def country_params
  params.require(:country).permit(:name, :description, regions_attributes: [:id, :name, :description])
end

country/_form.html.rb

<%= form_with(model: country, local: true) do |form| %>
  <% if country.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(country.errors.count, "error") %> prohibited this country from being saved:</h2>

      <ul>
      <% country.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= form.label :name %>
    <%= form.text_field :name, id: :country_name %>
  </div>

  <div class="field">
    <%= form.label :description %>
    <%= form.text_field :description, id: :country_description %>
  </div>
      //nested region form
      <%= form.fields_for :region do |region| %>
    <p>
        Region: <%= region.text_field :name %>
    </p>
    <% end %>

  <div class="actions">
    <%= form.submit %>
  </div>
<% end %>

Update

Region isn't a permitted parameter. Checking the controller, I have it as a parameter?

  Parameters: {"utf8"=>"✓", "authenticity_token"=>"wUtZvA8rMeQ12onWg+B4OcbzGzZOIDOLwi99Aef3SnjAg5yyYA0qI8wNJIl41u/S0+RIlMAvkVwWVyWWPF3Ocg==", "country"=>{"name"=>"Guatemala", "description"=>"", "region"=>{"name"=>"Candelaria"}}, "commit"=>"Create Country"}
Unpermitted parameter: :region
   (0.1ms)  BEGIN
  SQL (0.8ms)  INSERT INTO "countries" ("name", "description", "created_at", "updated_at") VALUES ($1, $2, $3, $4) RETURNING "id"  [["name", "Guatemala"], ["description", ""], ["created_at", "2018-02-02 22:21:24.093876"], ["updated_at", "2018-02-02 22:21:24.093876"]]
   (0.3ms)  COMMIT
Redirected to http://localhost:3000/countries/10
Completed 302 Found in 5ms (ActiveRecord: 1.2ms)

Update 2

I am now getting regions param allowed, but it seems I'm not actually sending any instruction to create the region. I've therefore added:

  def new
    @country = Country.new
    @country.region.build  //doesn't work
    @country.regions.build //doesn't work
    @country.build_region  //doesn't work
    @country.build_regions //doesn't work
  end

but this just produces the error undefined method 'build' for nil:NilClass

Pablo · Accepted Answer · 2018-02-03 00:36:07Z

1

I would change:

<%= form.fields_for :region do |region| %>
  <p>
    Region: <%= region.text_field :name %>
  </p>
<% end %>

with

<%= form.fields_for :regions do |region| %>
  <p>
    Region: <%= region.text_field :name %>
  </p>
<% end %>

or

<%= form.fields_for country.regions.build do |region| %>
  <p>
    Region: <%= region.text_field :name %>
  </p>
<% end %>

answered Feb 3, 2018 at 0:36

Pablo

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2 Comments

Simon Cooper Over a year ago

Hey Pablo. Have updated the form to regions but as per Update to in OP., I realised I hadn't actually been instructing the code to write to that field. That said, I get a new error undefined method build

Pablo Over a year ago

Well. @country.regions.build should work. :) I don't see anything wrong.

razvans · Accepted Answer · 2018-02-02 23:07:06Z

0

You set up your view & strong parameters to support a has_one :region association. has_many :regions has some gotchas. You can try cocoon, Nested forms in rails - accessing attribute in has_many relation

edited Feb 2, 2018 at 23:07

answered Feb 2, 2018 at 21:38

razvans

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4 Comments

Simon Cooper Over a year ago

doesn't look like region is a permitted paramater. put the log output in OP

razvans Over a year ago

What you try to do and what I answered is for has_one :region association. If you change that it will work. For has_many :regions you have to do country.regions.build hand handle differently in strong params.

razvans Over a year ago

@SimonCooper update the answer for has_one :region association.

razvans Over a year ago

@SimonCooper Completely changed the answer. Hope it helps

thedanotto · Accepted Answer · 2018-02-03 01:18:12Z

0

Update

<%= form.fields_for :region do |region| %>

to

<%= form.fields_for :regions do |region| %>

answered Feb 3, 2018 at 1:18

thedanotto

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