git post-checkout hook to check django migrations

post-checkout

#!/usr/bin/env python
import sys
import subprocess
from collections import defaultdict

fn, previous_head, current_head, is_branch = sys.argv
if not is_branch == '1':
    sys.exit(0)

diff = defaultdict(list)
output = subprocess.check_output(
    'git --no-pager diff --name-status %s %s ' % (
        previous_head, current_head), shell=True)
for i in output.split('\n'):
    if not i:
        continue
    op, fname = i.split('\t')
    diff[op].append(fname)

to_revert = []
for i in diff.get('D', []):
    if 'migrations' in i:
        to_revert.append(i)

to_run = []
for i in diff.get('A', []):
    if 'migrations' in i:
        to_run.append(i)

if to_revert:
    print('\nATTENTION!!!\n'
          'You have deleted migrations in this branch.\n'
          'You may need to return to the previous one and revert those:')
    for i in to_revert:
        print('\t * %s' % i)
    print('\nPlease ignore this warning if you\'ve already done it')

if to_run:
    print('You have new migrations in this branch:')
    for i in to_run:
        print(i)

print('You can see the migrations by running:')
print('python manage.py migrate --list')