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# -*- coding: utf-8 -*-
import os
import inspect
import re
from django.core.management.base import BaseCommand, CommandError
from django.db import DEFAULT_DB_ALIAS, connections
from django.db.migrations.loader import AmbiguityError, MigrationLoader
REPLACES_REGEX = re.compile(r"\s+replaces\s*=\s*\[[^\]]+\]\s*")
PYC = ".pyc"
def py_from_pyc(pyc_fn):
return pyc_fn[: -len(PYC)] + ".py"
class Command(BaseCommand):
help = (
"Deletes left over migrations that have been replaced by a "
"squashed migration and converts squashed migration into a normal "
"migration. Modifies your source tree! Use with care!"
)
def add_arguments(self, parser):
parser.add_argument(
"app_label",
help="App label of the application to delete replaced migrations from.",
)
parser.add_argument(
"squashed_migration_name",
default=None,
nargs="?",
help="The squashed migration to replace. "
"If not specified defaults to the first found.",
)
parser.add_argument(
"--noinput",
"--no-input",
action="store_false",
dest="interactive",
default=True,
help="Tells Django to NOT prompt the user for input of any kind.",
)
parser.add_argument(
"--dry-run",
action="store_true",
default=False,
help="Do not actually delete or change any files",
)
parser.add_argument(
"--database",
default=DEFAULT_DB_ALIAS,
help=(
"Nominates a database to run command for. "
'Defaults to the "%s" database.'
)
% DEFAULT_DB_ALIAS,
)
def handle(self, **options):
self.verbosity = options["verbosity"]
self.interactive = options["interactive"]
self.dry_run = options["dry_run"]
app_label = options["app_label"]
squashed_migration_name = options["squashed_migration_name"]
database = options["database"]
# Load the current graph state
# check the app and migration they asked for exists
loader = MigrationLoader(connections[database])
if app_label not in loader.migrated_apps:
raise CommandError(
"App '%s' does not have migrations (so delete_squashed_migrations on "
"it makes no sense)" % app_label
)
squashed_migration = None
if squashed_migration_name:
squashed_migration = self.find_migration(
loader, app_label, squashed_migration_name
)
if not squashed_migration.replaces:
raise CommandError(
"The migration %s %s is not a squashed migration."
% (squashed_migration.app_label, squashed_migration.name)
)
else:
leaf_nodes = loader.graph.leaf_nodes(app=app_label)
migration = loader.get_migration(*leaf_nodes[0])
previous_migrations = [
loader.get_migration(al, mn)
for al, mn in loader.graph.forwards_plan(
(migration.app_label, migration.name)
)
if al == migration.app_label
]
migrations = previous_migrations + [migration]
for migration in migrations:
if migration.replaces:
squashed_migration = migration
break
if not squashed_migration:
raise CommandError(
"Cannot find a squashed migration in app '%s'." % (app_label)
)
files_to_delete = []
for al, mn in squashed_migration.replaces:
try:
migration = loader.disk_migrations[al, mn]
except KeyError:
if self.verbosity > 0:
self.stderr.write(
"Couldn't find migration file for %s %s\n" % (al, mn)
)
else:
pyc_file = inspect.getfile(migration.__class__)
files_to_delete.append(pyc_file)
if pyc_file.endswith(PYC):
py_file = py_from_pyc(pyc_file)
files_to_delete.append(py_file)
# Tell them what we're doing and optionally ask if we should proceed
if self.verbosity > 0 or self.interactive:
self.stdout.write(
self.style.MIGRATE_HEADING("Will delete the following files:")
)
for fn in files_to_delete:
self.stdout.write(" - %s" % fn)
if not self.confirm():
return
for fn in files_to_delete:
try:
if not self.dry_run:
os.remove(fn)
except OSError:
if self.verbosity > 0:
self.stderr.write("Couldn't delete %s\n" % (fn,))
# Try and delete replaces only if it's all on one line
squashed_migration_fn = inspect.getfile(squashed_migration.__class__)
if squashed_migration_fn.endswith(PYC):
squashed_migration_fn = py_from_pyc(squashed_migration_fn)
with open(squashed_migration_fn) as fp:
squashed_migration_lines = list(fp)
delete_lines = []
for i, line in enumerate(squashed_migration_lines):
if REPLACES_REGEX.match(line):
delete_lines.append(i)
if i > 0 and squashed_migration_lines[i - 1].strip() == "":
delete_lines.insert(0, i - 1)
break
if not delete_lines:
raise CommandError(
(
"Couldn't find 'replaces =' line in file %s. "
"Please finish cleaning up manually."
)
% (squashed_migration_fn,)
)
if self.verbosity > 0 or self.interactive:
self.stdout.write(
self.style.MIGRATE_HEADING(
"Will delete line %s%s from file %s"
% (
delete_lines[0],
" and " + str(delete_lines[1]) if len(delete_lines) > 1 else "",
squashed_migration_fn,
)
)
)
if not self.confirm():
return
for line_num in sorted(delete_lines, reverse=True):
del squashed_migration_lines[line_num]
with open(squashed_migration_fn, "w") as fp:
if not self.dry_run:
fp.write("".join(squashed_migration_lines))
def confirm(self):
if self.interactive:
answer = None
while not answer or answer not in "yn":
answer = input("Do you wish to proceed? [yN] ")
if not answer:
answer = "n"
break
else:
answer = answer[0].lower()
return answer == "y"
return True
def find_migration(self, loader, app_label, name):
try:
return loader.get_migration_by_prefix(app_label, name)
except AmbiguityError:
raise CommandError(
"More than one migration matches '%s' in app '%s'. Please be "
"more specific." % (name, app_label)
)
except KeyError:
raise CommandError(
"Cannot find a migration matching '%s' from app '%s'."
% (name, app_label)
)
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