dump and load script to migrate from the alpha version of wimm to the latest

dump.py

# coding: utf-8

import json
import argparse
import os
import re
from pathlib import Path

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "wimm.settings")

import django
django.setup()

from item.models import Item


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='Dumps data from the database of the alpha '
                                                 'version wimm')
    parser.add_argument('out', help='Output path', type=Path)
    parser.add_argument('--meta-split', default=',', type=re.compile,
                        help='Split item meta by this regexp (default: %(default)s).'
                             'Trailing spaces are stripped.')
    parser.add_argument('--name-split', default=',', type=re.compile,
                        help='Split item name by this regexp (default: %(default)s).'
                             'Trailing spaces are stripped.')
    parser.add_argument('--keep-name', default=False, action='store_true',
                        help='Convert item name to a tag (default: %(default)s)')

    args = parser.parse_args()

    items = []
    for item in Item.objects.all().order_by('date'):
        row = {
            'date': item.date.isoformat(),
            'price': str(item.price),
            'tags': [_.strip() for _ in args.meta_split.split(item.meta) if _],
            'created_at': item.created_at.isoformat()
        }

        if args.keep_name:
            row['tags'] += [_.strip() for _ in args.name_split.split(item.name) if _]

        items.append(row)

    json.dump(items, args.out.open('w'), indent=4)

load.py

# coding: utf-8

import json
import argparse
import os
from pathlib import Path

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "wimm.settings")

import django
django.setup()

from django.db import transaction
from item.models import Item


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='Loads data from the result json of the'
                                                 'dump.py script')
    parser.add_argument('input', help='Input path', type=lambda x: Path(x).expanduser().resolve())
    args = parser.parse_args()

    with transaction.atomic():
        Item._meta.get_field('created_at').auto_now_add = False

        for i, item in enumerate(json.load(args.input.open())):
            obj = Item.objects.create(
                date=item['date'],
                price=item['price'],
                created_at=item['created_at']
            )

            obj.tags.add(*item['tags'])
            obj.save()