django/db/migrations/questioner.py
import datetime
import importlib
import os
import sys
from django.apps import apps
from django.core.management.base import OutputWrapper
from django.db.models import NOT_PROVIDED
from django.utils import timezone
from django.utils.version import get_docs_version
from .loader import MigrationLoader
class MigrationQuestioner:
"""
Give the autodetector responses to questions it might have.
This base class has a built-in noninteractive mode, but the
interactive subclass is what the command-line arguments will use.
"""
def __init__(self, defaults=None, specified_apps=None, dry_run=None):
self.defaults = defaults or {}
self.specified_apps = specified_apps or set()
self.dry_run = dry_run
def ask_initial(self, app_label):
"""Should we create an initial migration for the app?"""
# If it was specified on the command line, definitely true
if app_label in self.specified_apps:
return True
# Otherwise, we look to see if it has a migrations module
# without any Python files in it, apart from __init__.py.
# Apps from the new app template will have these; the Python
# file check will ensure we skip South ones.
try:
app_config = apps.get_app_config(app_label)
except LookupError: # It's a fake app.
return self.defaults.get("ask_initial", False)
migrations_import_path, _ = MigrationLoader.migrations_module(app_config.label)
if migrations_import_path is None:
# It's an application with migrations disabled.
return self.defaults.get("ask_initial", False)
try:
migrations_module = importlib.import_module(migrations_import_path)
except ImportError:
return self.defaults.get("ask_initial", False)
else:
if getattr(migrations_module, "__file__", None):
filenames = os.listdir(os.path.dirname(migrations_module.__file__))
elif hasattr(migrations_module, "__path__"):
if len(migrations_module.__path__) > 1:
return False
filenames = os.listdir(list(migrations_module.__path__)[0])
return not any(x.endswith(".py") for x in filenames if x != "__init__.py")
def ask_not_null_addition(self, field_name, model_name):
"""Adding a NOT NULL field to a model."""
# None means quit
return None
def ask_not_null_alteration(self, field_name, model_name):
"""Changing a NULL field to NOT NULL."""
# None means quit
return None
def ask_rename(self, model_name, old_name, new_name, field_instance):
"""Was this field really renamed?"""
return self.defaults.get("ask_rename", False)
def ask_rename_model(self, old_model_state, new_model_state):
"""Was this model really renamed?"""
return self.defaults.get("ask_rename_model", False)
def ask_merge(self, app_label):
"""Should these migrations really be merged?"""
return self.defaults.get("ask_merge", False)
def ask_auto_now_add_addition(self, field_name, model_name):
"""Adding an auto_now_add field to a model."""
# None means quit
return None
def ask_unique_callable_default_addition(self, field_name, model_name):
"""Adding a unique field with a callable default."""
# None means continue.
return None
class InteractiveMigrationQuestioner(MigrationQuestioner):
def __init__(
self, defaults=None, specified_apps=None, dry_run=None, prompt_output=None
):
super().__init__(
defaults=defaults, specified_apps=specified_apps, dry_run=dry_run
)
self.prompt_output = prompt_output or OutputWrapper(sys.stdout)
def _boolean_input(self, question, default=None):
self.prompt_output.write(f"{question} ", ending="")
result = input()
if not result and default is not None:
return default
while not result or result[0].lower() not in "yn":
self.prompt_output.write("Please answer yes or no: ", ending="")
result = input()
return result[0].lower() == "y"
def _choice_input(self, question, choices):
self.prompt_output.write(f"{question}")
for i, choice in enumerate(choices):
self.prompt_output.write(" %s) %s" % (i + 1, choice))
self.prompt_output.write("Select an option: ", ending="")
result = input()
while True:
try:
value = int(result)
except ValueError:
pass
else:
if 0 < value <= len(choices):
return value
self.prompt_output.write("Please select a valid option: ", ending="")
result = input()
def _ask_default(self, default=""):
"""
Prompt for a default value.
The ``default`` argument allows providing a custom default value (as a
string) which will be shown to the user and used as the return value
if the user doesn't provide any other input.
"""
self.prompt_output.write("Please enter the default value as valid Python.")
if default:
self.prompt_output.write(
f"Accept the default '{default}' by pressing 'Enter' or "
f"provide another value."
)
self.prompt_output.write(
"The datetime and django.utils.timezone modules are available, so "
"it is possible to provide e.g. timezone.now as a value."
)
self.prompt_output.write("Type 'exit' to exit this prompt")
while True:
if default:
prompt = "[default: {}] >>> ".format(default)
else:
prompt = ">>> "
self.prompt_output.write(prompt, ending="")
code = input()
if not code and default:
code = default
if not code:
self.prompt_output.write(
"Please enter some code, or 'exit' (without quotes) to exit."
)
elif code == "exit":
sys.exit(1)
else:
try:
return eval(code, {}, {"datetime": datetime, "timezone": timezone})
except (SyntaxError, NameError) as e:
self.prompt_output.write("Invalid input: %s" % e)
def ask_not_null_addition(self, field_name, model_name):
"""Adding a NOT NULL field to a model."""
if not self.dry_run:
choice = self._choice_input(
f"It is impossible to add a non-nullable field '{field_name}' "
f"to {model_name} without specifying a default. This is "
f"because the database needs something to populate existing "
f"rows.\n"
f"Please select a fix:",
[
(
"Provide a one-off default now (will be set on all existing "
"rows with a null value for this column)"
),
"Quit and manually define a default value in models.py.",
],
)
if choice == 2:
sys.exit(3)
else:
return self._ask_default()
return None
def ask_not_null_alteration(self, field_name, model_name):
"""Changing a NULL field to NOT NULL."""
if not self.dry_run:
choice = self._choice_input(
f"It is impossible to change a nullable field '{field_name}' "
f"on {model_name} to non-nullable without providing a "
f"default. This is because the database needs something to "
f"populate existing rows.\n"
f"Please select a fix:",
[
(
"Provide a one-off default now (will be set on all existing "
"rows with a null value for this column)"
),
"Ignore for now. Existing rows that contain NULL values "
"will have to be handled manually, for example with a "
"RunPython or RunSQL operation.",
"Quit and manually define a default value in models.py.",
],
)
if choice == 2:
return NOT_PROVIDED
elif choice == 3:
sys.exit(3)
else:
return self._ask_default()
return None
def ask_rename(self, model_name, old_name, new_name, field_instance):
"""Was this field really renamed?"""
msg = "Was %s.%s renamed to %s.%s (a %s)? [y/N]"
return self._boolean_input(
msg
% (
model_name,
old_name,
model_name,
new_name,
field_instance.__class__.__name__,
),
False,
)
def ask_rename_model(self, old_model_state, new_model_state):
"""Was this model really renamed?"""
msg = "Was the model %s.%s renamed to %s? [y/N]"
return self._boolean_input(
msg
% (old_model_state.app_label, old_model_state.name, new_model_state.name),
False,
)
def ask_merge(self, app_label):
return self._boolean_input(
"\nMerging will only work if the operations printed above do not conflict\n"
+ "with each other (working on different fields or models)\n"
+ "Should these migration branches be merged? [y/N]",
False,
)
def ask_auto_now_add_addition(self, field_name, model_name):
"""Adding an auto_now_add field to a model."""
if not self.dry_run:
choice = self._choice_input(
f"It is impossible to add the field '{field_name}' with "
f"'auto_now_add=True' to {model_name} without providing a "
f"default. This is because the database needs something to "
f"populate existing rows.\n",
[
"Provide a one-off default now which will be set on all "
"existing rows",
"Quit and manually define a default value in models.py.",
],
)
if choice == 2:
sys.exit(3)
else:
return self._ask_default(default="timezone.now")
return None
def ask_unique_callable_default_addition(self, field_name, model_name):
"""Adding a unique field with a callable default."""
if not self.dry_run:
version = get_docs_version()
choice = self._choice_input(
f"Callable default on unique field {model_name}.{field_name} "
f"will not generate unique values upon migrating.\n"
f"Please choose how to proceed:\n",
[
f"Continue making this migration as the first step in "
f"writing a manual migration to generate unique values "
f"described here: "
f"https://docs.djangoproject.com/en/{version}/howto/"
f"writing-migrations/#migrations-that-add-unique-fields.",
"Quit and edit field options in models.py.",
],
)
if choice == 2:
sys.exit(3)
return None
class NonInteractiveMigrationQuestioner(MigrationQuestioner):
def __init__(
self,
defaults=None,
specified_apps=None,
dry_run=None,
verbosity=1,
log=None,
):
self.verbosity = verbosity
self.log = log
super().__init__(
defaults=defaults,
specified_apps=specified_apps,
dry_run=dry_run,
)
def log_lack_of_migration(self, field_name, model_name, reason):
if self.verbosity > 0:
self.log(
f"Field '{field_name}' on model '{model_name}' not migrated: "
f"{reason}."
)
def ask_not_null_addition(self, field_name, model_name):
# We can't ask the user, so act like the user aborted.
self.log_lack_of_migration(
field_name,
model_name,
"it is impossible to add a non-nullable field without specifying "
"a default",
)
sys.exit(3)
def ask_not_null_alteration(self, field_name, model_name):
# We can't ask the user, so set as not provided.
self.log(
f"Field '{field_name}' on model '{model_name}' given a default of "
f"NOT PROVIDED and must be corrected."
)
return NOT_PROVIDED
def ask_auto_now_add_addition(self, field_name, model_name):
# We can't ask the user, so act like the user aborted.
self.log_lack_of_migration(
field_name,
model_name,
"it is impossible to add a field with 'auto_now_add=True' without "
"specifying a default",
)
sys.exit(3)