Add on_delete to Django models for upgrading to 2.0

ondelete.py

import os
import re


fk = re.compile(r'\s*([^\s]+)\s*=\s*models\.?(ForeignKey|OneToOneField)\(([^\s,\)]+)')


def fix(path, line):
    line = line.rstrip()
    # Weed out non-FKs, FKs with on_delete, or incomplete lines (will need to be done manually)
    if ('ForeignKey' not in line and 'OneToOneField' not in line) or 'on_delete' in line or not line.endswith(')'):
        return line
    if fk.match(line):
        if 'null=True' in line:
            line = line[:-1] + ', on_delete=models.SET_NULL)'
        else:
            line = line[:-1] + ', on_delete=models.CASCADE)'
        print(path, line)
    return line


if __name__ == '__main__':
    for root, dirs, files in os.walk('.'):
        for name in files:
            if name == 'models.py':
                lines = []
                path = os.path.join(root, name)
                with open(path, 'r') as f:
                    for line in f:
                        lines.append(fix(path, line))
                with open(path, 'w') as f:
                    f.write('\n'.join(lines))