Script that performs mail merge using pandoc, jinja2, and pdftk.

pandoc-merge.py

#!/usr/bin/env python3
import sys
import argparse
import logging
import csv
import subprocess
import tempfile
from pathlib import Path

from jinja2 import Template


def merge(input_file, csv_file, output_file, extra_args):
    template = Template(input_file.read_text())
    tempdir = tempfile.TemporaryDirectory(
        prefix='pandoc_merge_',
        dir=input_file.parent)
    tempdir_path = Path(tempdir.name)
    logging.debug(f'Using temporary directory {tempdir_path}.')
    output_files = []
    with csv_file.open() as csvfile:
        for i, data in enumerate(csv.DictReader(csvfile)):
            content = template.render(**data)
            tmpname = f'temp{i:05d}'
            tmppath = (tempdir_path / tmpname).with_suffix(output_file.suffix)
            output_files.append(tmppath)
            cmd = ['pandoc', '-o', tmppath] + extra_args
            subprocess.run(cmd, input=content, text=True, check=True)
    subprocess.run(['pdftk'] + output_files + ['cat', 'output', output_file])
    tempdir.cleanup()


def main():
    # Parse commandline arguments
    arg_parser = argparse.ArgumentParser()
    arg_parser.add_argument('-v', '--verbose', action='store_true')
    arg_parser.add_argument('--csv', type=Path)
    arg_parser.add_argument('-o', '--outfile', type=Path)
    arg_parser.add_argument('input', type=Path)
    args, extra_args = arg_parser.parse_known_args()
    # Set up logging
    if args.verbose:
        level = logging.DEBUG
    else:
        level = logging.ERROR
    logging.basicConfig(level=level)
    # Return exit value
    merge(args.input, args.csv, args.outfile, extra_args)
    return 0


if __name__ == '__main__':
    sys.exit(main())