How to set the right index on nested fields_for? - ruby-on-rails

Question

I got a problem with nested fields_for in rails, I have a list of products and each product can have multiple images, so I use Angular.js to complete this task, I followed this tutorial https://tatey.com/2013/01/13/adding-and-removing-children-with-rails-nested-forms-and-angularjs/ , but the names of the inputs doesn't have the right name because the index doesn't increment at the first param only on the second, like this:
First product has two images so this are the names assigned to each input
catalog[products_attributes][0][images_products_attributes][0][url_image]
catalog[products_attributes][0][images_products_attributes][1][url_image]
The second product has one image and this are the names of the attributes
catalog[products_attributes][0][images_products_attributes][0][url_image]
As you can see the second product has the index 0 on the products_attributes but it should be 1
This is my code
<div ng-repeat="product in products">
<div class="product">
<%= f.fields_for :products, Product.new do |product|%>
<div class="field">
Producto {{$index}}
<%= product.text_field :name, placeholder: "Nombre"%>
</div>
<div class="field">
<%= product.text_field :description, placeholder: "Descripción" %>
</div>
<div class="field">
<%= product.number_field :price, placeholder: "Precio" %>
</div>
<div class="field">
<%= product.check_box :available %>
</div>
<input type="button" name="name" value="+" ng-click="addImageToProduct($index)">
<div class="images">
<div class="image" ng-repeat="image in product.images">
<%= product.fields_for :images_products, ImagesProduct.new, child_index: "{{$index}}" do |image|%>
<div class="field">
{{$index}}<%= image.file_field :url_image%>
</div>
<%end%>
<input type="button" name="name" value="-" ng-click="removeImageToProduct($parent.$index, $index)">
</div>
</div>
<%end%>
</div>
<input class="step-button remove" type="button" name="name" value="Quitar" ng-click="removeProduct($index)">
</div>

Answer 1

Remove the child_index from your forms
child_index: "{{$index}}"
And puts the code already generated in the view with:
catalog[products_attributes][{{$parent.$index}}][images_products_attributes][$index][url_image]