How can I access YAML fields that are not considered metadata from a LUA filter?

[pagiraud]

Description

Hi,
Actually this might be very simple but I didn’t find any information…

I’m creating a Lua filter and I need to access data in the YAML header of the .qmd file that are not returned as metadata by Pandoc. How can I access them so I can use them in my filter?

An example:

---
title: "Some title"
format:
  beamer:
    aspectratio: 169
filters:
  - myfilter
---

Some data.

How can I access the aspectratio element? Of course, I could add some lines such as

myfilter:
  customaspectratio: 169

But I would prefer to avoid this solution.

[pagiraud]

I just should have looked more carefully at the "works" output… I tried to access it with m.format.beamer.aspectratio when it was simply m.aspectratio.