How to access nested metadata having a key with dots

[cscheid]

Let's support something like {{< meta nested.a\.b\.c.key >}}

(Then we ofc also need to figure out what to do with keys that have backslashes in them.0

Discussed in #10914

^{Originally posted by vlcinsky September 28, 2024}

Description

My sample index.qmd:

---
title: My Page
nested:
  a.b.c:
    key: Show me
---

I would like to show the "Show me" using a shortcode.

E.g. {{< meta nested["a.b.c"]key >}}

but it fails.

My question is: is there a syntax for accessing keys, which include dot(s) in their name?

[mcanouil]

Wouldn't it be "simpler/better" to support the square brackets (with inside quotes) notation?

[cscheid]

Wouldn't it be "simpler/better" to support the square brackets (with inside quotes) notation?

It would be significantly worse - now we have to care about parsing square brackets and matched quotes.

[mcanouil]

I was thinking of using the arg as "raw" and evaluate it it on meta but I'm not sure that's something even possible in LUA (also while writing it, might be a bad idea with a possible risk to inject code, although with the computations everywhere, that's not really a new risks😅).

[cscheid]

I was thinking of using the arg as "raw" and evaluate it it on meta

And then someone writes a function call in there. eval is a bad idea in general, it makes both error reporting and "restricting" the feature essentially impossible.

[cscheid]

The actual syntax needs to have an extra \ in it, but #10937 will enable {{< meta nested.a\\.b\\.c.key >}} It's not particularly pleasing to the eye, but it's narrow and safe, and I hope this is sufficiently rarely used anyway...

[vlcinsky]

My use case is to use value from existing meta variable to pick up value available in var.

---
domain-name: "registr.dopravninfo.cz"
---

Title of the domain is {{{< var domain-titles[{{< meta domain-name >}}] >}}

The syntax in last line above is completely made up.

I guess, I will have to use python block to do so.

[mcanouil]

Well, shortcode in shortcode is not something documented because that's not really supported.
Here, you should use conditional content based on meta value.

[cscheid]

I think the easiest way to achieve what you want here is through a Lua filter. You should have access to metadata contents there.