Unwrapping a Markdown table with a Pandoc Lua filter - lua

Question

I have a DOCX file with this content:
# Heading
+---------------------+
| Paragraph |
| |
| ## Subheading |
| |
| +-----------------+ |
| | Nested table | |
| +-----------------+ |
+---------------------+
One last paragraph
Here is a sample file.
I want to run it through Pandoc and get this Markdown, with all tables unwrapped:
# Heading
Paragraph
## Subheading
Nested table
One last paragraph
I'm trying to write a Lua filter with walk_block but I have no experience with Lua and not making any progress. Can anyone point me in a helpful direction?
function Table(table)
pandoc.walk_block(table, {
Str = function(el)
-- TODO now what???
end
})
end

Answer 1

The Lua interface to tables is currently rather complex, so it's much simpler to convert the table into a so-called simple table. We can do so with pandoc.utils.to_simple_table. A simple table has a header row (header) and multiple body rows (rows), and we get access to cells by iterating over a row. Each cell is just a Blocks list, which we can collect in an accumulator.
Here's how this looks like:
function Table (tbl)
local simpleTable = pandoc.utils.to_simple_table(tbl)
local blocks = pandoc.Blocks{}
for _, headercell in ipairs(simpleTable.header) do
blocks:extend(headercell)
end
for _, row in ipairs(simpleTable.rows) do
for _, cell in ipairs(row) do
blocks:extend(cell)
end
end
return blocks, false
end
Running that filter should unwrap all tables, leaving just their contents.