import io
import os
import sys
import warnings
from itertools import takewhile
from django.apps import apps
from django.conf import settings
from django.core.management.base import BaseCommand, CommandError
from django.db import DEFAULT_DB_ALIAS, connections, router
from django.db.migrations import Migration
from django.db.migrations.autodetector import MigrationAutodetector
from django.db.migrations.loader import MigrationLoader
from django.db.migrations.questioner import (
InteractiveMigrationQuestioner, MigrationQuestioner,
NonInteractiveMigrationQuestioner,
)
from django.db.migrations.state import ProjectState
from django.db.migrations.utils import get_migration_name_timestamp
from django.db.migrations.writer import MigrationWriter
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.six import iteritems
from django.utils.six.moves import zip
class Command(BaseCommand):
help = "Creates new migration(s) for apps."
def add_arguments(self, parser):
parser.add_argument(
'args', metavar='app_label', nargs='*',
help='Specify the app label(s) to create migrations for.',
)
parser.add_argument(
'--dry-run', action='store_true', dest='dry_run', default=False,
help="Just show what migrations would be made; don't actually write them.",
)
parser.add_argument(
'--merge', action='store_true', dest='merge', default=False,
help="Enable fixing of migration conflicts.",
)
parser.add_argument(
'--empty', action='store_true', dest='empty', default=False,
help="Create an empty migration.",
)
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(
'-n', '--name', action='store', dest='name', default=None,
help="Use this name for migration file(s).",
)
parser.add_argument(
'-e', '--exit', action='store_true', dest='exit_code', default=False,
help='Exit with error code 1 if no changes needing migrations are found. '
'Deprecated, use the --check option instead.',
)
parser.add_argument(
'--check', action='store_true', dest='check_changes',
help='Exit with a non-zero status if model changes are missing migrations.',
)
def handle(self, *app_labels, **options):
self.verbosity = options['verbosity']
self.interactive = options['interactive']
self.dry_run = options['dry_run']
self.merge = options['merge']
self.empty = options['empty']
self.migration_name = options['name']
self.exit_code = options['exit_code']
check_changes = options['check_changes']
if self.exit_code:
warnings.warn(
"The --exit option is deprecated in favor of the --check option.",
RemovedInDjango20Warning
)
# Make sure the app they asked for exists
app_labels = set(app_labels)
bad_app_labels = set()
for app_label in app_labels:
try:
apps.get_app_config(app_label)
except LookupError:
bad_app_labels.add(app_label)
if bad_app_labels:
for app_label in bad_app_labels:
self.stderr.write("App '%s' could not be found. Is it in INSTALLED_APPS?" % app_label)
sys.exit(2)
# Load the current graph state. Pass in None for the connection so
# the loader doesn't try to resolve replaced migrations from DB.
loader = MigrationLoader(None, ignore_no_migrations=True)
# Raise an error if any migrations are applied before their dependencies.
consistency_check_labels = set(config.label for config in apps.get_app_configs())
# Non-default databases are only checked if database routers used.
aliases_to_check = connections if settings.DATABASE_ROUTERS else [DEFAULT_DB_ALIAS]
for alias in sorted(aliases_to_check):
connection = connections[alias]
if (connection.settings_dict['ENGINE'] != 'django.db.backends.dummy' and any(
# At least one model must be migrated to the database.
router.allow_migrate(connection.alias, app_label, model_name=model._meta.object_name)
for app_label in consistency_check_labels
for model in apps.get_app_config(app_label).get_models()
)):
loader.check_consistent_history(connection)
# Before anything else, see if there's conflicting apps and drop out
# hard if there are any and they don't want to merge
conflicts = loader.detect_conflicts()
# If app_labels is specified, filter out conflicting migrations for unspecified apps
if app_labels:
conflicts = {
app_label: conflict for app_label, conflict in iteritems(conflicts)
if app_label in app_labels
}
if conflicts and not self.merge:
name_str = "; ".join(
"%s in %s" % (", ".join(names), app)
for app, names in conflicts.items()
)
raise CommandError(
"Conflicting migrations detected; multiple leaf nodes in the "
"migration graph: (%s).\nTo fix them run "
"'python manage.py makemigrations --merge'" % name_str
)
# If they want to merge and there's nothing to merge, then politely exit
if self.merge and not conflicts:
self.stdout.write("No conflicts detected to merge.")
return
# If they want to merge and there is something to merge, then
# divert into the merge code
if self.merge and conflicts:
return self.handle_merge(loader, conflicts)
if self.interactive:
questioner = InteractiveMigrationQuestioner(specified_apps=app_labels, dry_run=self.dry_run)
else:
questioner = NonInteractiveMigrationQuestioner(specified_apps=app_labels, dry_run=self.dry_run)
# Set up autodetector
autodetector = MigrationAutodetector(
loader.project_state(),
ProjectState.from_apps(apps),
questioner,
)
# If they want to make an empty migration, make one for each app
if self.empty:
if not app_labels:
raise CommandError("You must supply at least one app label when using --empty.")
# Make a fake changes() result we can pass to arrange_for_graph
changes = {
app: [Migration("custom", app)]
for app in app_labels
}
changes = autodetector.arrange_for_graph(
changes=changes,
graph=loader.graph,
migration_name=self.migration_name,
)
self.write_migration_files(changes)
return
# Detect changes
changes = autodetector.changes(
graph=loader.graph,
trim_to_apps=app_labels or None,
convert_apps=app_labels or None,
migration_name=self.migration_name,
)
if not changes:
# No changes? Tell them.
if self.verbosity >= 1:
if len(app_labels) == 1:
self.stdout.write("No changes detected in app '%s'" % app_labels.pop())
elif len(app_labels) > 1:
self.stdout.write("No changes detected in apps '%s'" % ("', '".join(app_labels)))
else:
self.stdout.write("No changes detected")
if self.exit_code:
sys.exit(1)
else:
self.write_migration_files(changes)
if check_changes:
sys.exit(1)
def write_migration_files(self, changes):
"""
Takes a changes dict and writes them out as migration files.
"""
directory_created = {}
for app_label, app_migrations in changes.items():
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Migrations for '%s':" % app_label) + "\n")
for migration in app_migrations:
# Describe the migration
writer = MigrationWriter(migration)
if self.verbosity >= 1:
# Display a relative path if it's below the current working
# directory, or an absolute path otherwise.
try:
migration_string = os.path.relpath(writer.path)
except ValueError:
migration_string = writer.path
if migration_string.startswith('..'):
migration_string = writer.path
self.stdout.write(" %s\n" % (self.style.MIGRATE_LABEL(migration_string),))
for operation in migration.operations:
self.stdout.write(" - %s\n" % operation.describe())
if not self.dry_run:
# Write the migrations file to the disk.
migrations_directory = os.path.dirname(writer.path)
if not directory_created.get(app_label):
if not os.path.isdir(migrations_directory):
os.mkdir(migrations_directory)
init_path = os.path.join(migrations_directory, "__init__.py")
if not os.path.isfile(init_path):
open(init_path, "w").close()
# We just do this once per app
directory_created[app_label] = True
migration_string = writer.as_string()
with io.open(writer.path, "w", encoding='utf-8') as fh:
fh.write(migration_string)
elif self.verbosity == 3:
# Alternatively, makemigrations --dry-run --verbosity 3
# will output the migrations to stdout rather than saving
# the file to the disk.
self.stdout.write(self.style.MIGRATE_HEADING(
"Full migrations file '%s':" % writer.filename) + "\n"
)
self.stdout.write("%s\n" % writer.as_string())
def handle_merge(self, loader, conflicts):
"""
Handles merging together conflicted migrations interactively,
if it's safe; otherwise, advises on how to fix it.
"""
if self.interactive:
questioner = InteractiveMigrationQuestioner()
else:
questioner = MigrationQuestioner(defaults={'ask_merge': True})
for app_label, migration_names in conflicts.items():
# Grab out the migrations in question, and work out their
# common ancestor.
merge_migrations = []
for migration_name in migration_names:
migration = loader.get_migration(app_label, migration_name)
migration.ancestry = [
mig for mig in loader.graph.forwards_plan((app_label, migration_name))
if mig[0] == migration.app_label
]
merge_migrations.append(migration)
def all_items_equal(seq):
return all(item == seq[0] for item in seq[1:])
merge_migrations_generations = zip(*[m.ancestry for m in merge_migrations])
common_ancestor_count = sum(1 for common_ancestor_generation
in takewhile(all_items_equal, merge_migrations_generations))
if not common_ancestor_count:
raise ValueError("Could not find common ancestor of %s" % migration_names)
# Now work out the operations along each divergent branch
for migration in merge_migrations:
migration.branch = migration.ancestry[common_ancestor_count:]
migrations_ops = (loader.get_migration(node_app, node_name).operations
for node_app, node_name in migration.branch)
migration.merged_operations = sum(migrations_ops, [])
# In future, this could use some of the Optimizer code
# (can_optimize_through) to automatically see if they're
# mergeable. For now, we always just prompt the user.
if self.verbosity > 0:
self.stdout.write(self.style.MIGRATE_HEADING("Merging %s" % app_label))
for migration in merge_migrations:
self.stdout.write(self.style.MIGRATE_LABEL(" Branch %s" % migration.name))
for operation in migration.merged_operations:
self.stdout.write(" - %s\n" % operation.describe())
if questioner.ask_merge(app_label):
# If they still want to merge it, then write out an empty
# file depending on the migrations needing merging.
numbers = [
MigrationAutodetector.parse_number(migration.name)
for migration in merge_migrations
]
try:
biggest_number = max(x for x in numbers if x is not None)
except ValueError:
biggest_number = 1
subclass = type("Migration", (Migration, ), {
"dependencies": [(app_label, migration.name) for migration in merge_migrations],
})
migration_name = "%04i_%s" % (
biggest_number + 1,
self.migration_name or ("merge_%s" % get_migration_name_timestamp())
)
new_migration = subclass(migration_name, app_label)
writer = MigrationWriter(new_migration)
if not self.dry_run:
# Write the merge migrations file to the disk
with io.open(writer.path, "w", encoding='utf-8') as fh:
fh.write(writer.as_string())
if self.verbosity > 0:
self.stdout.write("\nCreated new merge migration %s" % writer.path)
elif self.verbosity == 3:
# Alternatively, makemigrations --merge --dry-run --verbosity 3
# will output the merge migrations to stdout rather than saving
# the file to the disk.
self.stdout.write(self.style.MIGRATE_HEADING(
"Full merge migrations file '%s':" % writer.filename) + "\n"
)
self.stdout.write("%s\n" % writer.as_string())