Adding additional lua-filter into YAML - r

Question

I'm trying to add an additional lua-filter into the YAML:
---
title: "TITLE"
subtitle: "SUBTITLE"
date: "07/04/2022"
output:
pdf_document:
pandoc_args:
- --lua-filter=/Users/user/.local/share/pandoc/filters/wordcount.lua
latex_engine: pdflatex
includes:
in_header: style.sty
#keep_tex: true
bookdown::pdf_book:
citation_package: biblatex
bibliography: literature.bib
csl: my.csl
lang: de
fontsize: 12pt
---
ok, now when I try to knit the document I'm getting this erorr:
/usr/local/bin/pandoc +RTS -K512m -RTS mother.knit.md --to latex --from markdown+autolink_bare_uris+tex_math_single_backslash --output mother.tex --lua-filter /Users/user/Library/R/x86_64/4.1/library/rmarkdown/rmarkdown/lua/pagebreak.lua --lua-filter /Users/user/Library/R/x86_64/4.1/library/rmarkdown/rmarkdown/lua/latex-div.lua --self-contained --highlight-style tango --pdf-engine pdflatex --include-in-header style.sty --variable graphics --lua-filter=/Users/user/.local/share/pandoc/filters/wordcount.lua --variable 'geometry:margin=1in' --citeproc
655 words in body
4171 characters in body
4791 characters in body (including spaces)
Error in readLines(con, warn = FALSE) : cannot open the connection
In addition: Warning message:
In readLines(con, warn = FALSE) :
cannot open file 'mother.tex': No such file or directory
What is wrong with the mother.tex? Why it's not been created?
Hope someone can help. Thanks already.

Answer 1

Ok, I struggled a little bit to find the right position for the wordcout: process argument.
But a solution for those one who try to achive a workaround could be the following:
edit the following file from https://github.com/pandoc/lua-filters/blob/04e2d663dcb374d2c79ad1a42a30714843cb4e40/wordcount/wordcount.lua
notice the comment-out lines in line 39-42 and 43-45
-- counts words in a document
words = 0
characters = 0
characters_and_spaces = 0
process_anyway = false
wordcount = {
Str = function(el)
-- we don't count a word if it's entirely punctuation:
if el.text:match("%P") then
words = words + 1
end
characters = characters + utf8.len(el.text)
characters_and_spaces = characters_and_spaces + utf8.len(el.text)
end,
Space = function(el)
characters_and_spaces = characters_and_spaces + 1
end,
Code = function(el)
_,n = el.text:gsub("%S+","")
words = words + n
text_nospace = el.text:gsub("%s", "")
characters = characters + utf8.len(text_nospace)
characters_and_spaces = characters_and_spaces + utf8.len(el.text)
end,
CodeBlock = function(el)
_,n = el.text:gsub("%S+","")
words = words + n
text_nospace = el.text:gsub("%s", "")
characters = characters + utf8.len(text_nospace)
characters_and_spaces = characters_and_spaces + utf8.len(el.text)
end
}
-- check if the `wordcount` variable is set to `process-anyway`
--function Meta(meta)
-- if meta.wordcount and (meta.wordcount=="process-anyway"
-- or meta.wordcount=="process" or meta.wordcount=="convert") then
process_anyway = true
-- end
--end
function Pandoc(el)
-- skip metadata, just count body:
pandoc.walk_block(pandoc.Div(el.blocks), wordcount)
print(words .. " words in body")
print(characters .. " characters in body")
print(characters_and_spaces .. " characters in body (including spaces)")
if not process_anyway then
os.exit(0)
end
end

Answer 2

The problem is that the filter stops the conversion process, so no output is created.
I'm assuming you are using the wordcount filter from https://github.com/pandoc/lua-filters. That filter will abort the document conversion unless the metadata field wordcount is set to the string process or convert.
So you can add --metadata=wordcount=process this to pandoc_args setting:
pandoc_args:
- --lua-filter=/Users/user/.local/share/pandoc/filters/wordcount.lua
- --metadata=wordcount=process
or modify the filter to always process the document regardless of whether the metadata field is set or not.