Rails 4, double-nested models and strong parameters - ruby-on-rails

Question

I am fairly new to Ruby on Rails and began with rails 4 right away.
I have sucessfully nested a Recipe and a Ingredient model so that they can be added in the same form. Next I want to nest quantity within ingredient so that that aswell can be added within the same form. Everything seems to be working fine up until when the quantity of the ingredient is about to be inserted in the database and from this i believe there is something wrong with the strong params in the recipes_controller. But i will post the full code below.
I am using simple_form for the forms.
Thankful for any help!
Here are my models:
class Recipe < ActiveRecord::Base
has_many :comments, dependent: :destroy
has_many :ingredients, dependent: :destroy
accepts_nested_attributes_for :ingredients, :reject_if => lambda { |a| a[:name].blank? }, :allow_destroy => true
validates :title, presence: true
validates :desc, presence: true
end
class Ingredient < ActiveRecord::Base
belongs_to :recipe
has_many :quantities, dependent: :destroy
accepts_nested_attributes_for :quantities, :reject_if => lambda { |a| a[:name].blank? }, :allow_destroy => true
end
class Quantity < ActiveRecord::Base
belongs_to :ingredient
end
Here is the recipes_controller
class RecipesController < ApplicationController
def new
#recipe = Recipe.new
3.times do
ingredient = #recipe.ingredients.build
1.times {ingredient.quantities.build }
end
end
def create
#recipe = Recipe.new(params[:recipe].permit(:title, :desc, ingredients_attributes: [:id, :recipe_id, :name, :_destroy, quantities_attributes: [:id, :ingredient_id, :amount, :unit, :_destroy]]))
if #recipe.save
redirect_to #recipe
else
render "new"
end
end
def show
#recipe = Recipe.find(params[:id])
end
def edit
#recipe = Recipe.find(params[:id])
end
def update
#recipe = Recipe.find(params[:id])
if #recipe.update(params[:recipe].permit(:title, :desc))
redirect_to #recipe
else
render 'edit'
end
end
def destroy
#recipe = Recipe.find(params[:id])
#recipe.destroy
redirect_to recipes_path
end
def index
#recipes = Recipe.all
end
private
def post_params
params.require(:recipe).permit(:title, :desc, ingredients_attributes: [:id, :recipe_id, :name, :_destroy, quantities_attributes: [:id, :ingredient_id, :amount, :unit, :_destroy]])
end
end
Then i use simple form to create a form for recipe, ingredient and quantity through partials.
_form:
<%= simple_form_for #recipe do |f| %>
<%= f.error_notification %>
<%= f.input :title %>
<%= f.input :desc %>
<%= f.simple_fields_for :ingredients do |builder| %>
<%= render "ingredient_fields", :f => builder %>
<% end %>
<p class="links">
<%= link_to_add_association 'add ingredient', f, :ingredients %>
<p class="links">
<%= f.error :base%>
<%= f.submit %>
<% end %>
Which renders from _ingredients_fields:
<div class="nested-fields">
<%= f.input :name, label: "Ingredient" %>
<%= f.simple_fields_for :quantities do |builder| %>
<%= render "quantities_fields", :f => builder %>
<% end %>
<%= link_to_remove_association "remove", f %>
</div>
which renders from _quantities_fields: [EDITED]
<div class="nested-fields">
<%= f.input :amount %>
<%= f.input :unit %>
</div>
Trying to add new recipes result in the following log statement:
Started POST "/recipes" for 127.0.0.1 at 2013-10-29 14:15:40 +0100
Processing by RecipesController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"t6LKgDLwAxaU9xo2ipyCM+j1yfVF9WrI8AoGTX+gRkw=", "recipe"=>{"title"=>"Pancakes", "desc"=>"Tasty", "ingredients_attributes"=>{"0"=>{"name"=>"Milk", "quantities_attributes"=>{"0"=>{"amount"=>"1", "unit"=>"Cup"}}, "_destroy"=>"false"}}}, "commit"=>"Create Recipe"}
[1m[35m (0.1ms)[0m begin transaction
[1m[36mSQL (3.5ms)[0m [1mINSERT INTO "recipes" ("created_at", "desc", "title", "updated_at") VALUES (?, ?, ?, ?)[0m [["created_at", Tue, 29 Oct 2013 13:15:40 UTC +00:00], ["desc", "Tasty"], ["title", "Pancakes"], ["updated_at", Tue, 29 Oct 2013 13:15:40 UTC +00:00]]
[1m[35mSQL (0.4ms)[0m INSERT INTO "ingredients" ("created_at", "name", "recipe_id", "updated_at") VALUES (?, ?, ?, ?) [["created_at", Tue, 29 Oct 2013 13:15:40 UTC +00:00], ["name", "Milk"], ["recipe_id", 27], ["updated_at", Tue, 29 Oct 2013 13:15:40 UTC +00:00]]
[1m[36m (7.8ms)[0m [1mcommit transaction[0m
Redirected to http://www.projectcookbook.dev/recipes/27
Completed 302 Found in 22ms (ActiveRecord: 11.7ms)

Answer 1

You're using similar render for _quantities and _ingredients partials, which is wrong. In _quantities_field you don't need
<%= f.simple_fields_for :quantities do |builder| %>
<%= render "quantities_fields", :f => builder %>
<% end %>
AND should adjust
<%= f.input :name, label: "Quantity" %>
in _quantities_fields.
UPD
I think the problem is in :reject_if-clause at Ingredient model. It should be
:reject_if => lambda { |a| a[:amount].blank? }
bc here you specify conditions for Quantity, not for Ingredient
On code styling:
1) In controller it's better to use relevant name of private method for strong parameters: recipe_params instead of post_params and then use it for creation of new Recipe #recipe = Recipe.new(recipe_params)
2) Current associations between Recipe, Ingredient and Quantity will lead to Ingredient duplication in case two Recipes use similar one. The reason is belongs_to, which define single association. Try another approach (bellow).
BTW. recently I've answered on the similar question. Check it out: How do I reference an existing instance of a model in a nested Rails form?

Answer 2

I thing you are missing in this part
<%= simple_form_for #recipe do |f| %>
it should be
<%= simple_nested_form_for #recipe do |f| %>