Pandoc filter for embedding file in Latex output

[BongoKnight]

Context

I use Obsidian for taking notes and often I embed files directly in the note. Including files in Obsidian works the same way as embeding an image.

![Alt text](myfile.zip)

I made a template to convert notes to PDF.

I would like to embed files in the generated output as this could be very handy for sharing document mentioned during a team meetup or to share document linked to the content of the note.

Solution

It is possible to embed files in PDF output thanks to the \embedfile{} Latex instruction.

I would like to make a filter to make the following transform (pseudocode) :

if output format is Latex:
  if image.path matchs this regex ("\.(zip|pdf|py|xlsx|docx)$")
     return "(cf image.alttext) \embedfile{image.path})"

I seems really simple but I struggle a lot with the LUA syntax! ^^'

[BongoKnight]

Here is a python filter which does that :

from pandocfilters import toJSONFilter, RawInline, Str, Image
import re
from pathlib import Path

def latex(x):
    return RawInline('latex', x)


def latexembed(key, value, format, meta):
    if format == "latex":
        if key == 'Image':
            placeholder_image = Path(__file__).parent / 'paperclip.png'
            style, caption, file = value
            path = file[0]
            if headers := meta.get("header-includes"):
                if absolute_path_regex := re.search(r"graphicspath\{\{([^\}]+)\}\}", str(headers)):
                    path = absolute_path_regex.group(1) + path
            if re.search(r"\.(csv|xlsx|pdf|py|zip|md|txt|docx)$", path, flags=re.IGNORECASE):
                replacement =  "\\includegraphics[height=0.5cm]{"+ str(placeholder_image.as_posix()) + "} "
                return ([latex(replacement), Str(Path(path).name), latex("\\embedfile{" + path + "}")])


if __name__ == "__main__":
    toJSONFilter(latexembed)

This solution need a file saved with the name paperclip.png in the same dir as the filter.

This way attachments are displayed in the PDF Viewer, for exemple with Adobe Acrobat Reader :