Rails 5: Nested params not nested with has_many :through - ruby-on-rails

Question

I'm trying to create a form in Rails 5.2 for a model with a has_many :through relationship to another model. The form needs to include nested attributes for the other model. However, the params are not nesting properly. I've created the following minimal example.
Here are my models:
class Order < ApplicationRecord
has_many :component_orders, dependent: :restrict_with_exception
has_many :components, through: :component_orders
accepts_nested_attributes_for :components
end
class Component < ApplicationRecord
has_many :component_orders, dependent: :restrict_with_exception
has_many :orders, through: :component_orders
end
class ComponentOrder < ApplicationRecord
belongs_to :component
belongs_to :order
end
The Component and Order models each have one attribute: :name.
Here is my form code:
<%= form_with model: #order do |f| %>
<%= f.label :name %>
<%= f.text_field :name %>
<%= fields_for :components do |builder| %>
<%= builder.label :name %>
<%= builder.text_field :name %>
<% end %>
<%= f.submit %>
<% end %>
When I fill out the form, I get the following params:
{"utf8"=>"✓", "authenticity_token"=>"ztA1D9MBp1IRPsiZnnSAIl2sEYjFeincKxivoq0/pUO+ptlcfi6VG+ibBnSREqGq3VzckyRfkQtkCTDqvnTDjg==", "order"=>{"name"=>"Hello"}, "components"=>{"name"=>"World"}, "commit"=>"Create Order", "controller"=>"orders", "action"=>"create"}
Specifically, note that instead of a param like this:
{
"order" => {
"name" => "Hello",
"components_attributes" => {
"0" => {"name" => "World"}
}
}
}
There are separate keys for "order" and "components" at the same level. How can I cause these attributes to nest properly? Thank you!
EDIT: Here is my controller code:
class OrdersController < ApplicationController
def new
#order = Order.new
end
def create
#order = Order.new(order_params)
if #order.save
render json: #order, status: :created
else
render :head, status: :unprocessable_entity
end
end
private
def order_params
params.require(:order).permit(:name, components_attributes: [:name])
end
end

Answer 1

You should include accepts_nested_attributes_for :components in the Order model.
class Order < ApplicationRecord
has_many :component_orders, dependent: :restrict_with_exception
has_many :components, through: :component_orders
accepts_nested_attributes_for :components
end
And change
<%= fields_for :components do |builder| %>
to
<%= f.fields_for :components do |builder| %>
to get the desired params. accepts_nested_attributes_for :components creates a method namely components_attributes
More Info here