def migrate():
"""Migrate the database.
This is a simplified version of Django's ``migrate`` management command
that does not require ``management.call_command`` which is not functional
in the native binary environment.
"""
# Import the 'management' module within each installed app, to register
# dispatcher events.
verbosity = int(settings.DEBUG)
interactive = False
for app_config in apps.get_app_configs():
if module_has_submodule(app_config.module, "management"):
import_module(".management", app_config.name)
connection = connections[DEFAULT_DB_ALIAS]
connection.prepare_database()
executor = MigrationExecutor(connection, migration_progress_callback)
executor.loader.check_consistent_history(connection)
conflicts = executor.loader.detect_conflicts()
if conflicts:
raise Exception("Conflicting mgirations detected.")
targets = executor.loader.graph.leaf_nodes()
plan = executor.migration_plan(targets)
pre_migrate_state = executor._create_project_state(
with_applied_migrations=True)
pre_migrate_apps = pre_migrate_state.apps
emit_pre_migrate_signal(
verbosity,
False,
connection.alias,
apps=pre_migrate_apps,
plan=plan,
)
post_migrate_state = executor.migrate(
targets,
plan=plan,
state=pre_migrate_state.clone(),
fake=False,
fake_initial=False,
)
post_migrate_state.clear_delayed_apps_cache()
post_migrate_apps = post_migrate_state.apps
with post_migrate_apps.bulk_update():
model_keys = []
for model_state in post_migrate_apps.real_models:
model_key = model_state.app_label, model_state.name_lower
model_keys.append(model_key)
post_migrate_apps.unregister_model(*model_key)
post_migrate_apps.render_multiple([
ModelState.from_model(apps.get_model(*model)) for model in model_keys
])
emit_post_migrate_signal(
verbosity,
interactive,
connection.alias,
apps=post_migrate_apps,
plan=plan,
)
logger.info("Database configured.")
def on_pre_migrate(connection, **kwargs):
""" Ensures that custom user migration executed before main migration
process.
The main problem with existing application custom user implementation is
failing migration consistency check.
But in fact migration is ok, the problem is that migration plan
expects user migration applied before others.
So only thing we need to do, is to force custom user migration.
Here is approach when we detect such situation during migration process
and manually applying custom user migration before checks executed.
1. This method detects:
1.1. if it executed within migrate command
1.2. if other miggrations already applied
1.3. custom_user migrations not applied
2. Manually applies custom_user migration.
"""
if len(argv) < 2 or argv[1] != 'migrate':
return
executor = MigrationExecutor(connection, get_migration_callback())
executor.loader.load_disk()
is_fresh = not executor.loader.applied_migrations
is_applied = CUSTOM_USER_MIGRATION in executor.loader.applied_migrations
if is_fresh or is_applied:
return
migration = executor.loader.disk_migrations[CUSTOM_USER_MIGRATION]
state = executor._create_project_state(
with_applied_migrations=True) # noqa protected-access
executor.apply_migration(state, migration)
def migrate(app=None, migration=None):
from django.db.migrations.executor import MigrationExecutor
with transaction.atomic():
executor = MigrationExecutor(connection)
executor.loader.build_graph() # reload.
executor.loader.check_consistent_history(connection)
# Before anything else, see if there's conflicting apps and
# drop out hard if there are any
if executor.loader.detect_conflicts():
raise MigrationStructureError("Migrations have conflicts.")
# Handle
if app and migration:
targets = [(app, migration)]
elif app:
targets = [
key
for key
in executor.loader.graph.leaf_nodes()
if key[0] == app
]
else:
targets = executor.loader.graph.leaf_nodes()
plan = executor.migration_plan(targets)
pre_migrate_state = executor._create_project_state(
with_applied_migrations=True
)
post_migrate_state = executor.migrate(
targets, plan=plan, state=pre_migrate_state.clone()
)
post_migrate_state.clear_delayed_apps_cache()
return executor.loader.project_state(targets).apps
def migrate_migrations():
app_label = 'meta'
executor = MigrationExecutor(connection, migration_progress_callback)
pre_migrate_state = executor._create_project_state(
with_applied_migrations=True)
targets = [key for key in executor.loader.graph.leaf_nodes(app_label)
if key[0] == app_label]
plan = executor.migration_plan(targets)
if plan:
post_migrate_state = executor.migrate(
targets, plan=plan, state=pre_migrate_state.clone(), fake=False,
fake_initial=False,
)
def handle(self, *args, **options):
self.verbosity = options['verbosity']
self.interactive = options['interactive']
# Import the 'management' module within each installed app, to register
# dispatcher events.
for app_config in apps.get_app_configs():
if module_has_submodule(app_config.module, "management"):
import_module('.management', app_config.name)
db_routers = [
import_string(router)()
for router in conf.settings.DATABASE_ROUTERS
]
for connection in connections.all():
# Hook for backends needing any database preparation
connection.prepare_database()
# Work out which apps have migrations and which do not
executor = MigrationExecutor(connection,
self.migration_progress_callback)
# Raise an error if any migrations are applied before their dependencies.
executor.loader.check_consistent_history(connection)
# Before anything else, see if there's conflicting apps and drop out
# hard if there are any
conflicts = executor.loader.detect_conflicts()
if conflicts:
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 supplied command line arguments, work out what they mean.
targets, target_app_labels_only = self._get_targets(
connection, executor, db_routers, options)
plan = executor.migration_plan(targets)
run_syncdb = options[
'run_syncdb'] and executor.loader.unmigrated_apps
# Print some useful info
if self.verbosity >= 1:
self.stdout.write(
self.style.MIGRATE_HEADING("Operations to perform:"))
if run_syncdb:
self.stdout.write(
self.style.MIGRATE_LABEL(
" Synchronize unmigrated apps: ") +
(", ".join(sorted(executor.loader.unmigrated_apps))))
if target_app_labels_only:
self.stdout.write(
self.style.MIGRATE_LABEL(" Apply all migrations: ") +
(", ".join(sorted({a
for a, n in targets})) or "(none)"))
else:
if targets[0][1] is None:
self.stdout.write(
self.style.MIGRATE_LABEL(
" Unapply all migrations: ") + "%s" %
(targets[0][0], ))
else:
self.stdout.write(
self.style.MIGRATE_LABEL(
" Target specific migration: ") +
"%s, from %s" % (targets[0][1], targets[0][0]))
pre_migrate_state = executor._create_project_state(
with_applied_migrations=True)
pre_migrate_apps = pre_migrate_state.apps
emit_pre_migrate_signal(
self.verbosity,
self.interactive,
connection.alias,
apps=pre_migrate_apps,
plan=plan,
)
# Run the syncdb phase.
if run_syncdb:
self._syncdb_phase(connection, executor)
# Migrate!
self._migrate(plan, connection, executor, pre_migrate_state,
targets, options)
def handle(self, *args, **options):
self.branch = options['branch']
self.verbosity = options['verbosity']
self.interactive = options['interactive']
# Import the 'management' module within each installed app, to register
# dispatcher events.
for app_config in apps.get_app_configs():
if module_has_submodule(app_config.module, "management"):
import_module('.management', app_config.name)
# Get the database we're operating from
db = options['database']
connection = connections[db]
# Hook for backends needing any database preparation
connection.prepare_database()
# Work out which apps have migrations and which do not
executor = MigrationExecutor(connection,
self.migration_progress_callback)
# Raise an error if any migrations are applied before their dependencies.
executor.loader.check_consistent_history(connection)
targets = []
migrations = {}
migration_paths = self.get_diff_migrations()
# Group diff migrations by app_label
for p in migration_paths:
app_label = p.parts[0]
if app_label not in migrations:
# Validate app_label.
try:
apps.get_app_config(app_label)
except LookupError as err:
raise CommandError(str(err))
migrations[app_label] = []
migrations[app_label].append(p.stem)
# Get last applied migration for each app
for app_label, migration_names in migrations.items():
mr = MigrationRecorder.Migration.objects.filter(app=app_label)
# Skip if already unapplied
if not mr.filter(name__in=migration_names).count():
continue
mr = mr.exclude(
name__in=migration_names).order_by('applied').last()
if mr:
targets.append((app_label, mr.name))
if not targets:
if self.verbosity >= 1:
self.stdout.write(" No migrations to unapply.")
return
plan = executor.migration_plan(targets)
if options['plan']:
self.stdout.write('Planned operations:', self.style.MIGRATE_LABEL)
if not plan:
self.stdout.write(' No planned migration operations.')
for migration, backwards in plan:
self.stdout.write(str(migration), self.style.MIGRATE_HEADING)
for operation in migration.operations:
message, is_error = self.describe_operation(
operation, backwards)
style = self.style.WARNING if is_error else None
self.stdout.write(' ' + message, style)
return
# Print some useful info
if self.verbosity >= 1:
self.stdout.write(
self.style.MIGRATE_HEADING("Operations to perform:"))
for app_label, migration_name in targets:
self.stdout.write(
self.style.MIGRATE_LABEL(" Target specific migration: ") +
"%s, from %s" % (app_label, migration_name))
# noinspection PyProtectedMember
pre_migrate_state = executor._create_project_state(
with_applied_migrations=True)
pre_migrate_apps = pre_migrate_state.apps
emit_pre_migrate_signal(
self.verbosity,
self.interactive,
connection.alias,
apps=pre_migrate_apps,
plan=plan,
)
# Migrate!
if self.verbosity >= 1:
self.stdout.write(
self.style.MIGRATE_HEADING("Running migrations:"))
if not plan:
fake = False
fake_initial = False
else:
fake = options['fake']
fake_initial = options['fake_initial']
post_migrate_state = executor.migrate(
targets,
plan=plan,
state=pre_migrate_state.clone(),
fake=fake,
fake_initial=fake_initial,
)
# post_migrate signals have access to all models. Ensure that all models
# are reloaded in case any are delayed.
post_migrate_state.clear_delayed_apps_cache()
post_migrate_apps = post_migrate_state.apps
# Re-render models of real apps to include relationships now that
# we've got a final state. This wouldn't be necessary if real apps
# models were rendered with relationships in the first place.
with post_migrate_apps.bulk_update():
model_keys = []
for model_state in post_migrate_apps.real_models:
model_key = model_state.app_label, model_state.name_lower
model_keys.append(model_key)
post_migrate_apps.unregister_model(*model_key)
post_migrate_apps.render_multiple([
ModelState.from_model(apps.get_model(*model))
for model in model_keys
])
# Send the post_migrate signal, so individual apps can do whatever they need
# to do at this point.
emit_post_migrate_signal(
self.verbosity,
self.interactive,
connection.alias,
apps=post_migrate_apps,
plan=plan,
)
def handle(self, *args, **options):
database = options['database']
if not options['skip_checks']:
self.check(databases=[database])
self.verbosity = options['verbosity']
self.interactive = options['interactive']
# Import the 'management' module within each installed BLOG, to register
# dispatcher events.
for app_config in apps.get_app_configs():
if module_has_submodule(app_config.module, "management"):
import_module('.management', app_config.name)
# Get the database we're operating from
connection = connections[database]
# Hook for backends needing any database preparation
connection.prepare_database()
# Work out which apps have migrations and which do not
executor = MigrationExecutor(connection, self.migration_progress_callback)
# Raise an error if any migrations are applied before their dependencies.
executor.loader.check_consistent_history(connection)
# Before anything else, see if there's conflicting apps and drop out
# hard if there are any
conflicts = executor.loader.detect_conflicts()
if conflicts:
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 supplied command line arguments, work out what they mean.
run_syncdb = options['run_syncdb']
target_app_labels_only = True
if options['app_label']:
# Validate app_label.
app_label = options['app_label']
try:
apps.get_app_config(app_label)
except LookupError as err:
raise CommandError(str(err))
if run_syncdb:
if app_label in executor.loader.migrated_apps:
raise CommandError("Can't use run_syncdb with BLOG '%s' as it has migrations." % app_label)
elif app_label not in executor.loader.migrated_apps:
raise CommandError("App '%s' does not have migrations." % app_label)
if options['app_label'] and options['migration_name']:
migration_name = options['migration_name']
if migration_name == "zero":
targets = [(app_label, None)]
else:
try:
migration = executor.loader.get_migration_by_prefix(app_label, migration_name)
except AmbiguityError:
raise CommandError(
"More than one migration matches '%s' in BLOG '%s'. "
"Please be more specific." %
(migration_name, app_label)
)
except KeyError:
raise CommandError("Cannot find a migration matching '%s' from BLOG '%s'." % (
migration_name, app_label))
targets = [(app_label, migration.name)]
target_app_labels_only = False
elif options['app_label']:
targets = [key for key in executor.loader.graph.leaf_nodes() if key[0] == app_label]
else:
targets = executor.loader.graph.leaf_nodes()
plan = executor.migration_plan(targets)
exit_dry = plan and options['check_unapplied']
if options['plan']:
self.stdout.write('Planned operations:', self.style.MIGRATE_LABEL)
if not plan:
self.stdout.write(' No planned migration operations.')
for migration, backwards in plan:
self.stdout.write(str(migration), self.style.MIGRATE_HEADING)
for operation in migration.operations:
message, is_error = self.describe_operation(operation, backwards)
style = self.style.WARNING if is_error else None
self.stdout.write(' ' + message, style)
if exit_dry:
sys.exit(1)
return
if exit_dry:
sys.exit(1)
# At this point, ignore run_syncdb if there aren't any apps to sync.
run_syncdb = options['run_syncdb'] and executor.loader.unmigrated_apps
# Print some useful info
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Operations to perform:"))
if run_syncdb:
if options['app_label']:
self.stdout.write(
self.style.MIGRATE_LABEL(" Synchronize unmigrated BLOG: %s" % app_label)
)
else:
self.stdout.write(
self.style.MIGRATE_LABEL(" Synchronize unmigrated apps: ") +
(", ".join(sorted(executor.loader.unmigrated_apps)))
)
if target_app_labels_only:
self.stdout.write(
self.style.MIGRATE_LABEL(" Apply all migrations: ") +
(", ".join(sorted({a for a, n in targets})) or "(none)")
)
else:
if targets[0][1] is None:
self.stdout.write(
self.style.MIGRATE_LABEL(' Unapply all migrations: ') +
str(targets[0][0])
)
else:
self.stdout.write(self.style.MIGRATE_LABEL(
" Target specific migration: ") + "%s, from %s"
% (targets[0][1], targets[0][0])
)
pre_migrate_state = executor._create_project_state(with_applied_migrations=True)
pre_migrate_apps = pre_migrate_state.apps
emit_pre_migrate_signal(
self.verbosity, self.interactive, connection.alias, apps=pre_migrate_apps, plan=plan,
)
# Run the syncdb phase.
if run_syncdb:
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Synchronizing apps without migrations:"))
if options['app_label']:
self.sync_apps(connection, [app_label])
else:
self.sync_apps(connection, executor.loader.unmigrated_apps)
# Migrate!
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Running migrations:"))
if not plan:
if self.verbosity >= 1:
self.stdout.write(" No migrations to apply.")
# If there's changes that aren't in migrations yet, tell them how to fix it.
autodetector = MigrationAutodetector(
executor.loader.project_state(),
ProjectState.from_apps(apps),
)
changes = autodetector.changes(graph=executor.loader.graph)
if changes:
self.stdout.write(self.style.NOTICE(
" Your models in BLOG(s): %s have changes that are not "
"yet reflected in a migration, and so won't be "
"applied." % ", ".join(repr(app) for app in sorted(changes))
))
self.stdout.write(self.style.NOTICE(
" Run 'manage.py makemigrations' to make new "
"migrations, and then re-run 'manage.py migrate' to "
"apply them."
))
fake = False
fake_initial = False
else:
fake = options['fake']
fake_initial = options['fake_initial']
post_migrate_state = executor.migrate(
targets, plan=plan, state=pre_migrate_state.clone(), fake=fake,
fake_initial=fake_initial,
)
# post_migrate signals have access to all models. Ensure that all models
# are reloaded in case any are delayed.
post_migrate_state.clear_delayed_apps_cache()
post_migrate_apps = post_migrate_state.apps
# Re-render models of real apps to include relationships now that
# we've got a final state. This wouldn't be necessary if real apps
# models were rendered with relationships in the first place.
with post_migrate_apps.bulk_update():
model_keys = []
for model_state in post_migrate_apps.real_models:
model_key = model_state.app_label, model_state.name_lower
model_keys.append(model_key)
post_migrate_apps.unregister_model(*model_key)
post_migrate_apps.render_multiple([
ModelState.from_model(apps.get_model(*model)) for model in model_keys
])
# Send the post_migrate signal, so individual apps can do whatever they need
# to do at this point.
emit_post_migrate_signal(
self.verbosity, self.interactive, connection.alias, apps=post_migrate_apps, plan=plan,
)
def handle(self, *args, **options):
self.verbosity = options['verbosity']
self.interactive = options['interactive']
# Import the 'management' module within each installed app, to register
# dispatcher events.
for app_config in apps.get_app_configs():
if module_has_submodule(app_config.module, "management"):
import_module('.management', app_config.name)
# Get the database we're operating from
db = options['database']
connection = connections[db]
# Hook for backends needing any database preparation
connection.prepare_database()
# Work out which apps have migrations and which do not
executor = MigrationExecutor(connection, self.migration_progress_callback)
# Raise an error if any migrations are applied before their dependencies.
executor.loader.check_consistent_history(connection)
# Before anything else, see if there's conflicting apps and drop out
# hard if there are any
conflicts = executor.loader.detect_conflicts()
if conflicts:
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 supplied command line arguments, work out what they mean.
target_app_labels_only = True
if options['app_label']:
# Validate app_label.
app_label = options['app_label']
try:
apps.get_app_config(app_label)
except LookupError as err:
raise CommandError(str(err))
if app_label not in executor.loader.migrated_apps:
raise CommandError("App '%s' does not have migrations." % app_label)
if options['app_label'] and options['migration_name']:
migration_name = options['migration_name']
if migration_name == "zero":
targets = [(app_label, None)]
else:
try:
migration = executor.loader.get_migration_by_prefix(app_label, migration_name)
except AmbiguityError:
raise CommandError(
"More than one migration matches '%s' in app '%s'. "
"Please be more specific." %
(migration_name, app_label)
)
except KeyError:
raise CommandError("Cannot find a migration matching '%s' from app '%s'." % (
migration_name, app_label))
targets = [(app_label, migration.name)]
target_app_labels_only = False
elif options['app_label']:
targets = [key for key in executor.loader.graph.leaf_nodes() if key[0] == app_label]
else:
targets = executor.loader.graph.leaf_nodes()
plan = executor.migration_plan(targets)
if options['plan']:
self.stdout.write('Planned operations:', self.style.MIGRATE_LABEL)
if not plan:
self.stdout.write(' No planned migration operations.')
for migration, backwards in plan:
self.stdout.write(str(migration), self.style.MIGRATE_HEADING)
for operation in migration.operations:
message, is_error = self.describe_operation(operation, backwards)
style = self.style.WARNING if is_error else None
self.stdout.write(' ' + message, style)
return
run_syncdb = options['run_syncdb'] and executor.loader.unmigrated_apps
# Print some useful info
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Operations to perform:"))
if run_syncdb:
self.stdout.write(
self.style.MIGRATE_LABEL(" Synchronize unmigrated apps: ") +
(", ".join(sorted(executor.loader.unmigrated_apps)))
)
if target_app_labels_only:
self.stdout.write(
self.style.MIGRATE_LABEL(" Apply all migrations: ") +
(", ".join(sorted({a for a, n in targets})) or "(none)")
)
else:
if targets[0][1] is None:
self.stdout.write(self.style.MIGRATE_LABEL(
" Unapply all migrations: ") + "%s" % (targets[0][0],)
)
else:
self.stdout.write(self.style.MIGRATE_LABEL(
" Target specific migration: ") + "%s, from %s"
% (targets[0][1], targets[0][0])
)
pre_migrate_state = executor._create_project_state(with_applied_migrations=True)
pre_migrate_apps = pre_migrate_state.apps
emit_pre_migrate_signal(
self.verbosity, self.interactive, connection.alias, apps=pre_migrate_apps, plan=plan,
)
# Run the syncdb phase.
if run_syncdb:
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Synchronizing apps without migrations:"))
self.sync_apps(connection, executor.loader.unmigrated_apps)
# Migrate!
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Running migrations:"))
if not plan:
if self.verbosity >= 1:
self.stdout.write(" No migrations to apply.")
# If there's changes that aren't in migrations yet, tell them how to fix it.
autodetector = MigrationAutodetector(
executor.loader.project_state(),
ProjectState.from_apps(apps),
)
changes = autodetector.changes(graph=executor.loader.graph)
if changes:
self.stdout.write(self.style.NOTICE(
" Your models have changes that are not yet reflected "
"in a migration, and so won't be applied."
))
self.stdout.write(self.style.NOTICE(
" Run 'manage.py makemigrations' to make new "
"migrations, and then re-run 'manage.py migrate' to "
"apply them."
))
fake = False
fake_initial = False
else:
fake = options['fake']
fake_initial = options['fake_initial']
post_migrate_state = executor.migrate(
targets, plan=plan, state=pre_migrate_state.clone(), fake=fake,
fake_initial=fake_initial,
)
# post_migrate signals have access to all models. Ensure that all models
# are reloaded in case any are delayed.
post_migrate_state.clear_delayed_apps_cache()
post_migrate_apps = post_migrate_state.apps
# Re-render models of real apps to include relationships now that
# we've got a final state. This wouldn't be necessary if real apps
# models were rendered with relationships in the first place.
with post_migrate_apps.bulk_update():
model_keys = []
for model_state in post_migrate_apps.real_models:
model_key = model_state.app_label, model_state.name_lower
model_keys.append(model_key)
post_migrate_apps.unregister_model(*model_key)
post_migrate_apps.render_multiple([
ModelState.from_model(apps.get_model(*model)) for model in model_keys
])
# Send the post_migrate signal, so individual apps can do whatever they need
# to do at this point.
emit_post_migrate_signal(
self.verbosity, self.interactive, connection.alias, apps=post_migrate_apps, plan=plan,
)
def handle(self, *args, **options):
# self 是「命令处理对象」
print('【django.core.management.commands.migrate.Command.handle】args:',
args)
#print('【django.core.management.commands.migrate.Command.handle】options:' )
#for k, v in options.items():
# print(f'\t{k:<22}{v}')
database = options['database'] # 默认值是 'default'
if not options['skip_checks']:
# 此方法定义在父类 django.core.management.base.BaseCommand 中
self.check(databases=[database])
self.verbosity = options['verbosity']
self.interactive = options['interactive']
# Import the 'management' module within each installed app, to register
# dispatcher events.
for app_config in apps.get_app_configs():
if module_has_submodule(app_config.module, "management"):
import_module('.management', app_config.name)
# connections 是 django.db.utils.ConnectionHandler 类的实例，叫做「数据库连接处理对象」
# 此处调用其 __getitem__ 方法，返回的是「数据库包装对象」
# 以 MySQL 为例，其所属类定义在 django.db.backends.mysql.base 模块中
# 所以下面的 connection 是 django.db.backends.mysql.base.DatabaseWrapper 类的实例
connection = connections[database]
print(
'【django.core.management.commands.migrate.Command.handle】connection:',
connection)
# 此方法定义在实例的父类中，是空函数
connection.prepare_database()
# 下面这十几行代码用于处理数据版本控制相关的事情
# 此 MigrationExecutor 类定义在 django.db.migrations.executor 模块中，其实例是「数据库版本迁移执行器」
# 实例化时提供两个参数，它们分别会被赋值给实例的同名属性：
# connection 是「数据库包装对象」，这是位置参数
# process_callback 是可选参数，这里提供的是定义在当前类中的方法
executor = MigrationExecutor(connection,
self.migration_progress_callback)
# executor 是「数据库版本迁移执行器」
# executor.loader 是 django.db.migrations.loader.MigrationLoader 类的实例
# 该实例的 connection 属性值就是 self
executor.loader.check_consistent_history(connection)
# Before anything else, see if there's conflicting apps and drop out
# hard if there are any
conflicts = executor.loader.detect_conflicts()
if conflicts:
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 supplied command line arguments, work out what they mean.
run_syncdb = options['run_syncdb']
target_app_labels_only = True
if options['app_label']:
# Validate app_label.
app_label = options['app_label']
try:
apps.get_app_config(app_label)
except LookupError as err:
raise CommandError(str(err))
if run_syncdb:
if app_label in executor.loader.migrated_apps:
raise CommandError(
"Can't use run_syncdb with app '%s' as it has migrations."
% app_label)
elif app_label not in executor.loader.migrated_apps:
raise CommandError("App '%s' does not have migrations." %
app_label)
if options['app_label'] and options['migration_name']:
migration_name = options['migration_name']
if migration_name == "zero":
targets = [(app_label, None)]
else:
try:
migration = executor.loader.get_migration_by_prefix(
app_label, migration_name)
except AmbiguityError:
raise CommandError(
"More than one migration matches '%s' in app '%s'. "
"Please be more specific." %
(migration_name, app_label))
except KeyError:
raise CommandError(
"Cannot find a migration matching '%s' from app '%s'."
% (migration_name, app_label))
targets = [(app_label, migration.name)]
target_app_labels_only = False
elif options['app_label']:
targets = [
key for key in executor.loader.graph.leaf_nodes()
if key[0] == app_label
]
else:
# executor 是 django.db.migrations.executor.MigrationExecutor 类的实例
# 叫做「数据库版本迁移执行器」
# executor.loader 是 django.db.migrations.loader.MigrationLoader 类的实例
# 此实例的 graph 属性值是 django.db.migrations.graph.MigrationGraph 类的实例
# 调用其 leaf_nodes 获得各个应用中最新版本的迁移文件名
# targets 是列表，里面是二元元组，类似这样：
# [('admin', '0003_logentry_add_action_flag_choices'), ...]
targets = executor.loader.graph.leaf_nodes()
#print('【django.core.management.commands.migrate.Command.handle】targets:')
#for i in targets:
# print('\t', i)
# executor 是 django.db.migrations.executor.MigrationExecutor 类的实例
# 叫做「数据库版本迁移执行器」
plan = executor.migration_plan(targets)
exit_dry = plan and options['check_unapplied']
if options['plan']:
self.stdout.write('Planned operations:', self.style.MIGRATE_LABEL)
if not plan:
self.stdout.write(' No planned migration operations.')
for migration, backwards in plan:
self.stdout.write(str(migration), self.style.MIGRATE_HEADING)
for operation in migration.operations:
message, is_error = self.describe_operation(
operation, backwards)
style = self.style.WARNING if is_error else None
self.stdout.write(' ' + message, style)
if exit_dry:
sys.exit(1)
return
if exit_dry:
sys.exit(1)
# At this point, ignore run_syncdb if there aren't any apps to sync.
run_syncdb = options['run_syncdb'] and executor.loader.unmigrated_apps
# Print some useful info
if self.verbosity >= 1:
self.stdout.write(
self.style.MIGRATE_HEADING("Operations to perform:"))
if run_syncdb:
if options['app_label']:
self.stdout.write(
self.style.MIGRATE_LABEL(
" Synchronize unmigrated app: %s" % app_label))
else:
self.stdout.write(
self.style.MIGRATE_LABEL(
" Synchronize unmigrated apps: ") +
(", ".join(sorted(executor.loader.unmigrated_apps))))
if target_app_labels_only:
self.stdout.write(
self.style.MIGRATE_LABEL(" Apply all migrations: ") +
(", ".join(sorted({a
for a, n in targets})) or "(none)"))
else:
if targets[0][1] is None:
self.stdout.write(
self.style.MIGRATE_LABEL(' Unapply all migrations: ')
+ str(targets[0][0]))
else:
self.stdout.write(
self.style.MIGRATE_LABEL(
" Target specific migration: ") + "%s, from %s" %
(targets[0][1], targets[0][0]))
pre_migrate_state = executor._create_project_state(
with_applied_migrations=True)
pre_migrate_apps = pre_migrate_state.apps
emit_pre_migrate_signal(
self.verbosity,
self.interactive,
connection.alias,
apps=pre_migrate_apps,
plan=plan,
)
# Run the syncdb phase.
if run_syncdb:
if self.verbosity >= 1:
self.stdout.write(
self.style.MIGRATE_HEADING(
"Synchronizing apps without migrations:"))
if options['app_label']:
self.sync_apps(connection, [app_label])
else:
self.sync_apps(connection, executor.loader.unmigrated_apps)
# Migrate!
if self.verbosity >= 1:
self.stdout.write(
self.style.MIGRATE_HEADING("Running migrations:"))
if not plan:
if self.verbosity >= 1:
self.stdout.write(" No migrations to apply.")
# If there's changes that aren't in migrations yet, tell them how to fix it.
autodetector = MigrationAutodetector(
executor.loader.project_state(),
ProjectState.from_apps(apps),
)
changes = autodetector.changes(graph=executor.loader.graph)
if changes:
self.stdout.write(
self.style.NOTICE(
" Your models have changes that are not yet reflected "
"in a migration, and so won't be applied."))
self.stdout.write(
self.style.NOTICE(
" Run 'manage.py makemigrations' to make new "
"migrations, and then re-run 'manage.py migrate' to "
"apply them."))
fake = False
fake_initial = False
else:
fake = options['fake']
fake_initial = options['fake_initial']
# executor 是 django.db.migrations.executor.MigrationExecutor 类的实例，叫做「数据库版本迁移执行器」
# 参数：
# targets 列表，里面是类似 ('auth', '0012_alter_user_first_name_max_length') 这样的元组
# plan 列表，里面是类似 (<Migration auth.0001_initial>, False) 这样的元组
post_migrate_state = executor.migrate(
targets,
plan=plan,
state=pre_migrate_state.clone(),
fake=fake,
fake_initial=fake_initial,
)
# post_migrate signals have access to all models. Ensure that all models
# are reloaded in case any are delayed.
post_migrate_state.clear_delayed_apps_cache()
post_migrate_apps = post_migrate_state.apps
# Re-render models of real apps to include relationships now that
# we've got a final state. This wouldn't be necessary if real apps
# models were rendered with relationships in the first place.
with post_migrate_apps.bulk_update():
model_keys = []
for model_state in post_migrate_apps.real_models:
model_key = model_state.app_label, model_state.name_lower
model_keys.append(model_key)
post_migrate_apps.unregister_model(*model_key)
post_migrate_apps.render_multiple([
ModelState.from_model(apps.get_model(*model))
for model in model_keys
])
# Send the post_migrate signal, so individual apps can do whatever they need
# to do at this point.
emit_post_migrate_signal(
self.verbosity,
self.interactive,
connection.alias,
apps=post_migrate_apps,
plan=plan,
)
def handle(self, *args, **options):
self.verbosity = options['verbosity']
self.interactive = options['interactive']
# @@ TODO あとで。
# managementを読んで何をしているのか。
# Import the 'management' module within each installed app, to register
# dispatcher events.
for app_config in apps.get_app_configs():
if module_has_submodule(app_config.module, "management"):
import_module('.management', app_config.name)
logger.debug('options {}'.format(options))
# @@ 普通は`default`が入っている
db = options['database']
# @@ 対応するDBへのコネクションラッパを取得する
# ConnectionHandler().__getitem__(db)
# django.db.backends.sqlite3.base.DatabaseWrapper が戻る
connection = connections[db]
logger.debug('connection {}'.format(connection))
# @@ sqlite3では未実装なのでpass
# 実際のところgisだけっぽい
# postgisのbaseより。
# def prepare_database(self):
# super().prepare_database()
# # Check that postgis extension is installed.
# with self.cursor() as cursor:
# cursor.execute("CREATE EXTENSION IF NOT EXISTS postgis")
connection.prepare_database()
# Work out which apps have migrations and which do not
# @@ executorの取得
# migration_progress_callbackは進捗をstdoutにいい感じにだすための処理
# DBから状態を取り出し、適用をするクラス
executor = MigrationExecutor(connection, self.migration_progress_callback)
# Raise an error if any migrations are applied before their dependencies.
# @@
# executor.loaderはMigrationLoader
# 適用済マイグレーションのツリーの一貫性チェック
# 適用されているマイグレーションのparentがgraph.nodesにあるかを見ている
# どこかで辿りきれなくなっているのはまずいので。どこかで流れが変わっている可能性がある
executor.loader.check_consistent_history(connection)
# Before anything else, see if there's conflicting apps and drop out
# hard if there are any
# @@ マイグレーションファイルのコンフリクトチェック
# 同じAppで複数のリーフが存在していないかを見ている
conflicts = executor.loader.detect_conflicts()
if conflicts:
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 supplied command line arguments, work out what they mean.
# @@ app_labelやmigration_nameの対応
# 該当する部分だけをdisk_migrationから取り出す
# 未指定なら全部の末端ノードを取り出す
target_app_labels_only = True
if options['app_label'] and options['migration_name']:
app_label, migration_name = options['app_label'], options['migration_name']
if app_label not in executor.loader.migrated_apps:
raise CommandError(
"App '%s' does not have migrations." % app_label
)
if migration_name == "zero":
targets = [(app_label, None)]
else:
try:
# @@
# migration_nameは前方一致で単一になればなんでもいい
migration = executor.loader.get_migration_by_prefix(app_label, migration_name)
except AmbiguityError:
raise CommandError(
"More than one migration matches '%s' in app '%s'. "
"Please be more specific." %
(migration_name, app_label)
)
except KeyError:
raise CommandError("Cannot find a migration matching '%s' from app '%s'." % (
migration_name, app_label))
targets = [(app_label, migration.name)]
target_app_labels_only = False
elif options['app_label']:
app_label = options['app_label']
if app_label not in executor.loader.migrated_apps:
raise CommandError(
"App '%s' does not have migrations." % app_label
)
targets = [key for key in executor.loader.graph.leaf_nodes() if key[0] == app_label]
else:
targets = executor.loader.graph.leaf_nodes()
logger.debug('migration target {}'.format(targets))
# @@
# 実際に適用すべきマイグレーションを決定する
plan = executor.migration_plan(targets)
logger.debug('plan {}'.format(plan))
# @@
# https://docs.djangoproject.com/en/2.0/ref/django-admin/#django-admin-migrate
# --run-syncdb¶
# Allows creating tables for apps without migrations. While this isn’t recommended,
# the migrations framework is sometimes too slow on large projects with hundreds of models.
# これのためにあるらしい
run_syncdb = options['run_syncdb'] and executor.loader.unmigrated_apps
logger.debug('executor.loader.unmigrated_apps {}'.format(executor.loader.unmigrated_apps))
# Print some useful info
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Operations to perform:"))
if run_syncdb:
self.stdout.write(
self.style.MIGRATE_LABEL(" Synchronize unmigrated apps: ") +
(", ".join(sorted(executor.loader.unmigrated_apps)))
)
if target_app_labels_only:
self.stdout.write(
self.style.MIGRATE_LABEL(" Apply all migrations: ") +
(", ".join(sorted({a for a, n in targets})) or "(none)")
)
else:
if targets[0][1] is None:
self.stdout.write(self.style.MIGRATE_LABEL(
" Unapply all migrations: ") + "%s" % (targets[0][0],)
)
else:
self.stdout.write(self.style.MIGRATE_LABEL(
" Target specific migration: ") + "%s, from %s"
% (targets[0][1], targets[0][0])
)
# @@ マイグレーション前のProjectStateを構成する
# 恐らく適用済の範囲だけっぽい
pre_migrate_state = executor._create_project_state(with_applied_migrations=True)
pre_migrate_apps = pre_migrate_state.apps
# @@ シグナルを投げる
# 最終的にinject_rename_contenttypes_operationsが呼ばれる
emit_pre_migrate_signal(
self.verbosity, self.interactive, connection.alias, apps=pre_migrate_apps, plan=plan,
)
# Run the syncdb phase.
if run_syncdb:
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Synchronizing apps without migrations:"))
self.sync_apps(connection, executor.loader.unmigrated_apps)
# Migrate!
if self.verbosity >= 1:
self.stdout.write(self.style.MIGRATE_HEADING("Running migrations:"))
# @@ 適用するものがなければメッセージ出すだけ
if not plan:
if self.verbosity >= 1:
self.stdout.write(" No migrations to apply.")
# If there's changes that aren't in migrations yet, tell them how to fix it.
# @@ これは優しさ
# もしmakemigrationsされてない変更があれば警告する
autodetector = MigrationAutodetector(
executor.loader.project_state(),
ProjectState.from_apps(apps),
)
changes = autodetector.changes(graph=executor.loader.graph)
if changes:
self.stdout.write(self.style.NOTICE(
" Your models have changes that are not yet reflected "
"in a migration, and so won't be applied."
))
self.stdout.write(self.style.NOTICE(
" Run 'manage.py makemigrations' to make new "
"migrations, and then re-run 'manage.py migrate' to "
"apply them."
))
fake = False
fake_initial = False
else:
fake = options['fake']
fake_initial = options['fake_initial']
# @@ migrateを実行する
post_migrate_state = executor.migrate(
targets, plan=plan, state=pre_migrate_state.clone(), fake=fake,
fake_initial=fake_initial,
)
# post_migrate signals have access to all models. Ensure that all models
# are reloaded in case any are delayed.
post_migrate_state.clear_delayed_apps_cache()
post_migrate_apps = post_migrate_state.apps
# Re-render models of real apps to include relationships now that
# we've got a final state. This wouldn't be necessary if real apps
# models were rendered with relationships in the first place.
with post_migrate_apps.bulk_update():
model_keys = []
for model_state in post_migrate_apps.real_models:
model_key = model_state.app_label, model_state.name_lower
model_keys.append(model_key)
post_migrate_apps.unregister_model(*model_key)
post_migrate_apps.render_multiple([
ModelState.from_model(apps.get_model(*model)) for model in model_keys
])
# Send the post_migrate signal, so individual apps can do whatever they need
# to do at this point.
emit_post_migrate_signal(
self.verbosity, self.interactive, connection.alias, apps=post_migrate_apps, plan=plan,
)