bug: quarto doesn't respect fenced divs for callouts in commonmark

[JosiahParry]

Description

Quarto doesn't respect fenced divs when rendering to commonmark with commonmark output. Note that pandoc does correctly handle this.

Given a qmd file like this

---
title: example
format: commonmark
---

::: callout-note
This is a callout not getting fenced div class
:::

then running quarto render test.qmd creates

# example


<div>

> **Note**
>
> This is a callout not getting fenced div class

</div>

when it should create

# example


<div class="callout-note">

This is a callout not getting fenced div class

</div>

[JosiahParry]

Note that pandoc works here:

blog-zola ⚡ pandoc test.qmd -t commonmark -f markdown
<div class="callout-note">

This is a callout not getting fenced div class

</div>

[cderv]

Quarto doesn't respect fenced divs when rendering to commonmark with commonmark output. Note that pandoc does correctly handle this.

Pandoc does not have callout support, so what are you expecting as result exactly?
Using callout-* class on a fenced div in quarto will trigger callout node, special from Quarto. pandoc does not have that, so for Pandoc this is a usual fenced div, for Quarto this is a Callout.

I am trying to clarify if you expect the class on the div, or no blockquote syntax ?

Defaults behavior of callouts is to be written as blockquotes in output. We do mention this in https://quarto.org/docs/authoring/callouts.html#format-support

When the target format doesn’t support callouts, they are rendered as a simple blockquote with the title in bold.

We have a special support for GFM that does support alert mode

Note

Like this note.

But for commonmark output, callouts will be a blockquote.

To remove this, you'll need to use a Lua filter. I don't think we have callout: false to opt-out the processing.
Or just to use a callout class on the fenced div.

We do keep the <div> because if you put an id, this is where it would go

::: {#nte-1 .callout-note}
This is a callout not getting fenced div class
:::

<div id="nte-1">

> **Note 1**
>
> This is a callout not getting fenced div class

</div>

but for now we do remove any other attributes.

So, can you please clarify what you expect as output when using a callout class on a fenced div callout-note ?

[JosiahParry]

Thank's both! I've spent some time checking out alternative approaches to this. There is no way to create a new format extension for type markdown. Using a lua filter (with help from claude) I cannot figure out how to modify callouts before quarto turns them into a blockquote.

[mcanouil]

You would need your filter to work before Quarto processes the document.
This is a bit hidden in the documentation unfortunately, but here is what you need: https://quarto.org/docs/prerelease/1.4/lua_changes.html#more-precise-targeting-of-ast-processing-phases

[cderv]

You would need your filter to work before Quarto processes the document

Not specifically before Quarto process callout as in process the markdown syntax, but it needs indeed to be before the render stage. But any filter inserted using filters should be by default applying before rendering stage.

The custom node addition in Quarto means that you can write a filter that target Callout node, and do whatever you want with them.

See https://quarto.org/docs/prerelease/1.3/ast.html

So with a lua filter that does

Callout = function(callout)
	-- do something with the callout content and attributes
end 

I acknowledge this means un-processing the callout in your case as you want to keep a fenced div. But what you want really is a custom format where callout are rendered as <div> in your markdown document.

We are working on improving the documentation on all this.

There is no way to create a new format extension for type markdown.

Regarding this, I am not following. custom formats can be derived from any supported formats: https://quarto.org/docs/extensions/formats.html
So you can have a format: zola-commonmark if you want.

However, if you just need Lua filters then you don't need a custom format I guess. Just adding filter to your blog project.

[mcanouil]

I acknowledge this means un-processing the callout in your case as you want to keep a fenced div. But what you want really is a custom format where callout are rendered as <div> in your markdown document.

That's why, having the filter before Quarto makes it a bit easier in my opinion than having to deal with callout node, as you only have to handle a regular div with .callout-* class. Then Quarto won't even see it.

[cderv]

Yes sure, that would work. I feel it is more about changing our callouts are rendered in this special output format, than changing how it is parsed to trick Quarto.

It is also possible to not use callout-* classes on div, and so have a usual fenced div with another class, that does not trigger callout. Maybe pre-filterlter could just be that - check for div, and change their class before AST processing. 🤷‍♂️

Lots of possibilities - as always no best solution in general, just a matter of choosing what suits best the workflow and project.