Access to product.metafields from a collection page using Custom Liquid

[alfontrok]

Hi,

I am building a custom liquid snippet and need to access product metafields.

Following the documentation was able to get all products data using

{% assign all_products = collection.products %}

so, when I try to access to:

all_products[0].metafields

I get undefined.

I could get all the product data info but could not get the metafields attributes.

I was following this doc

Some recommendations about it?

Thank you in advance