Support Frontmatter in MD files

[paulhibbitts]

Is your feature request related to a problem? Please describe.
I'd love to use the Collaborative editor to share Page files for the Grav CMS (a flat-file CMS). Right now any Frontmatter (https://jekyllrb.com/docs/front-matter/) originally in the file seems to be re-saved in a different format. Frontmatter is used quite widely in both static site generators and flat-file CMSs.

Here is a simple example of Frontmatter for testing purposes:

---
title: 'Classic Modern Architecture'
date: '17:34 06/27/2017'
---

Here is the main content area of the MD file.

When saved, this is the result:

---

title: 'Classic Modern Architecture' date: '17:34 06/27/2017'

Here is the main content area of the MD file.

Describe the solution you'd like
Any frontmatter contained in a MD should be visually distinct from the main content of the MD file, and also be editable (like a Code Block perhaps?)

Describe alternatives you've considered
I've not been able to find any so far.

Additional context
Add any other context or screenshots about the feature request here.

Thanks very much! The new collaborative editor is awesome to see in Nextcloud!

[juliusknorr]

Thanks for your suggestion. While front matter is not really specified in commonmark, I still agree that we should make sure that it is not changed. So we should make sure to strip it from the markdown parsing and add a simple code block for editing at the beginning of the document.

[paulhibbitts]

That sounds great @juliushaertl , thank you for considering this suggestion.

[brainchild0]

You could also consider rendering the displayable content, such as title, in appropriate styles. But somehow the user would need to able to add or to edit the other fields.

Also, not sure, but if the block is appearing disassembled after changes are saved, then maybe there is a separate issue with the way documents are processed. A MarkDown editor ideally should, I think, preserve as much literal content as possible from the original document, not attempt to produce an entirely new document from the logical features of the AST.

[hugoroy]

Hi, I think this feature is definitely important :-)

But I don't think it should be rendered as text like the rest. These blocks are supposed to be metadata (see, e.g. https://pandoc.org/MANUAL.html#extension-yaml_metadata_block which specifies it cleary, or https://jekyllrb.com/docs/front-matter/ which specifies it implicitly with the special rules IMO). The point is: you can have a lot more metadata in these blocks, not just "title" and "author" (I use them extensively to process with Pandoc). Trying to use them to render anything will probably lead to a lot of chaos…

So it probably requires a lot of work to get right from the UI/UX perspectives (the simple solution could be to treat it like a codeblock - but instead of inserting the codeblocks delimiter, use "---" and "---"; but this does not feel very satisfactory…)

[brainchild0]

But I don't think it should be rendered as text like the rest. These blocks are supposed to be metadata.

The point is: you can have a lot more metadata in these blocks, not just "title" and "author

The suggestion is not to render all metadata as stylized text, only the elements that appear visually in the document, such as title and author.

Naturally, other data must be shown in another manner. A collapsible code block would allow easy editing, while still offering a distraction-free view of the document that resembles final output with respect to display of the title and similar fields.