I am new to pandoc/Lua. I have a markdown file from our Gitlab repository I would like to locally convert using pandoc. The file contains ::include directives.

I have started doing a Lua filter for pandoc that replaces the ::include directives with the actual referred markdown. However, while the RawInline blocks I insert seem to be accepted, the --verbose output indicates that they are not rendered (the part I inserted is missing in the output HTML).

[INFO] Running filter gitlab-include.lua
[INFO] Completed filter gitlab-include.lua in 15 ms
[INFO] Not rendering RawInline (Format "markdown")[Markdown content included here]

The file in ::include{file=./my_file.md} is read correctly. If instead of RawInline I return the string, the unrendered markdown is included in the output. However, I did not manage to get the inserted content to be rendered as markdown.

Any clue as to what the filter is missing? Many thanks in advance.

The Lua filter is included below:

local function read_file(filepath)
    local file = io.open(filepath, "r")
    if not file then
        io.stderr:write("Cannot open file: " .. filepath .. "\n")
        return "**Error: Cannot include file " .. filepath .. "**"
    end
    local content = file:read("*all")   
    file:close()
    return pandoc.RawInline('markdown', content)
end

function replace_include(el)
    local pattern = "::include%{file=([^\"]+)%}"
    local filepath = el.text:match(pattern)
    if filepath then
        return read_file(filepath)
    end
    return el
end

return {
    { Str = replace_include }
}