django1/django/db/migrations/serializer.py

390 lines
14 KiB
Python

from __future__ import unicode_literals
import collections
import datetime
import decimal
import functools
import math
import types
from importlib import import_module
from django.db import models
from django.db.migrations.operations.base import Operation
from django.db.migrations.utils import COMPILED_REGEX_TYPE, RegexObject
from django.utils import datetime_safe, six
from django.utils.encoding import force_text
from django.utils.functional import LazyObject, Promise
from django.utils.timezone import utc
from django.utils.version import get_docs_version
try:
import enum
except ImportError:
# No support on Python 2 if enum34 isn't installed.
enum = None
class BaseSerializer(object):
def __init__(self, value):
self.value = value
def serialize(self):
raise NotImplementedError('Subclasses of BaseSerializer must implement the serialize() method.')
class BaseSequenceSerializer(BaseSerializer):
def _format(self):
raise NotImplementedError('Subclasses of BaseSequenceSerializer must implement the _format() method.')
def serialize(self):
imports = set()
strings = []
for item in self.value:
item_string, item_imports = serializer_factory(item).serialize()
imports.update(item_imports)
strings.append(item_string)
value = self._format()
return value % (", ".join(strings)), imports
class BaseSimpleSerializer(BaseSerializer):
def serialize(self):
return repr(self.value), set()
class ByteTypeSerializer(BaseSerializer):
def serialize(self):
value_repr = repr(self.value)
if six.PY2:
# Prepend the `b` prefix since we're importing unicode_literals
value_repr = 'b' + value_repr
return value_repr, set()
class DatetimeSerializer(BaseSerializer):
def serialize(self):
if self.value.tzinfo is not None and self.value.tzinfo != utc:
self.value = self.value.astimezone(utc)
value_repr = repr(self.value).replace("<UTC>", "utc")
if isinstance(self.value, datetime_safe.datetime):
value_repr = "datetime.%s" % value_repr
imports = ["import datetime"]
if self.value.tzinfo is not None:
imports.append("from django.utils.timezone import utc")
return value_repr, set(imports)
class DateSerializer(BaseSerializer):
def serialize(self):
value_repr = repr(self.value)
if isinstance(self.value, datetime_safe.date):
value_repr = "datetime.%s" % value_repr
return value_repr, {"import datetime"}
class DecimalSerializer(BaseSerializer):
def serialize(self):
return repr(self.value), {"from decimal import Decimal"}
class DeconstructableSerializer(BaseSerializer):
@staticmethod
def serialize_deconstructed(path, args, kwargs):
name, imports = DeconstructableSerializer._serialize_path(path)
strings = []
for arg in args:
arg_string, arg_imports = serializer_factory(arg).serialize()
strings.append(arg_string)
imports.update(arg_imports)
for kw, arg in sorted(kwargs.items()):
arg_string, arg_imports = serializer_factory(arg).serialize()
imports.update(arg_imports)
strings.append("%s=%s" % (kw, arg_string))
return "%s(%s)" % (name, ", ".join(strings)), imports
@staticmethod
def _serialize_path(path):
module, name = path.rsplit(".", 1)
if module == "django.db.models":
imports = {"from django.db import models"}
name = "models.%s" % name
else:
imports = {"import %s" % module}
name = path
return name, imports
def serialize(self):
return self.serialize_deconstructed(*self.value.deconstruct())
class DictionarySerializer(BaseSerializer):
def serialize(self):
imports = set()
strings = []
for k, v in sorted(self.value.items()):
k_string, k_imports = serializer_factory(k).serialize()
v_string, v_imports = serializer_factory(v).serialize()
imports.update(k_imports)
imports.update(v_imports)
strings.append((k_string, v_string))
return "{%s}" % (", ".join("%s: %s" % (k, v) for k, v in strings)), imports
class EnumSerializer(BaseSerializer):
def serialize(self):
enum_class = self.value.__class__
module = enum_class.__module__
imports = {"import %s" % module}
v_string, v_imports = serializer_factory(self.value.value).serialize()
imports.update(v_imports)
return "%s.%s(%s)" % (module, enum_class.__name__, v_string), imports
class FloatSerializer(BaseSimpleSerializer):
def serialize(self):
if math.isnan(self.value) or math.isinf(self.value):
return 'float("{}")'.format(self.value), set()
return super(FloatSerializer, self).serialize()
class FrozensetSerializer(BaseSequenceSerializer):
def _format(self):
return "frozenset([%s])"
class FunctionTypeSerializer(BaseSerializer):
def serialize(self):
if getattr(self.value, "__self__", None) and isinstance(self.value.__self__, type):
klass = self.value.__self__
module = klass.__module__
return "%s.%s.%s" % (module, klass.__name__, self.value.__name__), {"import %s" % module}
# Further error checking
if self.value.__name__ == '<lambda>':
raise ValueError("Cannot serialize function: lambda")
if self.value.__module__ is None:
raise ValueError("Cannot serialize function %r: No module" % self.value)
# Python 3 is a lot easier, and only uses this branch if it's not local.
if getattr(self.value, "__qualname__", None) and getattr(self.value, "__module__", None):
if "<" not in self.value.__qualname__: # Qualname can include <locals>
return "%s.%s" % \
(self.value.__module__, self.value.__qualname__), {"import %s" % self.value.__module__}
# Python 2/fallback version
module_name = self.value.__module__
# Make sure it's actually there and not an unbound method
module = import_module(module_name)
if not hasattr(module, self.value.__name__):
raise ValueError(
"Could not find function %s in %s.\n"
"Please note that due to Python 2 limitations, you cannot "
"serialize unbound method functions (e.g. a method "
"declared and used in the same class body). Please move "
"the function into the main module body to use migrations.\n"
"For more information, see "
"https://docs.djangoproject.com/en/%s/topics/migrations/#serializing-values"
% (self.value.__name__, module_name, get_docs_version())
)
# Needed on Python 2 only
if module_name == '__builtin__':
return self.value.__name__, set()
return "%s.%s" % (module_name, self.value.__name__), {"import %s" % module_name}
class FunctoolsPartialSerializer(BaseSerializer):
def serialize(self):
imports = {'import functools'}
# Serialize functools.partial() arguments
func_string, func_imports = serializer_factory(self.value.func).serialize()
args_string, args_imports = serializer_factory(self.value.args).serialize()
keywords_string, keywords_imports = serializer_factory(self.value.keywords).serialize()
# Add any imports needed by arguments
imports.update(func_imports)
imports.update(args_imports)
imports.update(keywords_imports)
return (
"functools.partial(%s, *%s, **%s)" % (
func_string, args_string, keywords_string,
),
imports,
)
class IterableSerializer(BaseSerializer):
def serialize(self):
imports = set()
strings = []
for item in self.value:
item_string, item_imports = serializer_factory(item).serialize()
imports.update(item_imports)
strings.append(item_string)
# When len(strings)==0, the empty iterable should be serialized as
# "()", not "(,)" because (,) is invalid Python syntax.
value = "(%s)" if len(strings) != 1 else "(%s,)"
return value % (", ".join(strings)), imports
class ModelFieldSerializer(DeconstructableSerializer):
def serialize(self):
attr_name, path, args, kwargs = self.value.deconstruct()
return self.serialize_deconstructed(path, args, kwargs)
class ModelManagerSerializer(DeconstructableSerializer):
def serialize(self):
as_manager, manager_path, qs_path, args, kwargs = self.value.deconstruct()
if as_manager:
name, imports = self._serialize_path(qs_path)
return "%s.as_manager()" % name, imports
else:
return self.serialize_deconstructed(manager_path, args, kwargs)
class OperationSerializer(BaseSerializer):
def serialize(self):
from django.db.migrations.writer import OperationWriter
string, imports = OperationWriter(self.value, indentation=0).serialize()
# Nested operation, trailing comma is handled in upper OperationWriter._write()
return string.rstrip(','), imports
class RegexSerializer(BaseSerializer):
def serialize(self):
imports = {"import re"}
regex_pattern, pattern_imports = serializer_factory(self.value.pattern).serialize()
regex_flags, flag_imports = serializer_factory(self.value.flags).serialize()
imports.update(pattern_imports)
imports.update(flag_imports)
args = [regex_pattern]
if self.value.flags:
args.append(regex_flags)
return "re.compile(%s)" % ', '.join(args), imports
class SequenceSerializer(BaseSequenceSerializer):
def _format(self):
return "[%s]"
class SetSerializer(BaseSequenceSerializer):
def _format(self):
# Don't use the literal "{%s}" as it doesn't support empty set
return "set([%s])"
class SettingsReferenceSerializer(BaseSerializer):
def serialize(self):
return "settings.%s" % self.value.setting_name, {"from django.conf import settings"}
class TextTypeSerializer(BaseSerializer):
def serialize(self):
value_repr = repr(self.value)
if six.PY2:
# Strip the `u` prefix since we're importing unicode_literals
value_repr = value_repr[1:]
return value_repr, set()
class TimedeltaSerializer(BaseSerializer):
def serialize(self):
return repr(self.value), {"import datetime"}
class TimeSerializer(BaseSerializer):
def serialize(self):
value_repr = repr(self.value)
if isinstance(self.value, datetime_safe.time):
value_repr = "datetime.%s" % value_repr
return value_repr, {"import datetime"}
class TupleSerializer(BaseSequenceSerializer):
def _format(self):
# When len(value)==0, the empty tuple should be serialized as "()",
# not "(,)" because (,) is invalid Python syntax.
return "(%s)" if len(self.value) != 1 else "(%s,)"
class TypeSerializer(BaseSerializer):
def serialize(self):
special_cases = [
(models.Model, "models.Model", []),
]
for case, string, imports in special_cases:
if case is self.value:
return string, set(imports)
if hasattr(self.value, "__module__"):
module = self.value.__module__
if module == six.moves.builtins.__name__:
return self.value.__name__, set()
else:
return "%s.%s" % (module, self.value.__name__), {"import %s" % module}
def serializer_factory(value):
from django.db.migrations.writer import SettingsReference
if isinstance(value, Promise):
value = force_text(value)
elif isinstance(value, LazyObject):
# The unwrapped value is returned as the first item of the arguments
# tuple.
value = value.__reduce__()[1][0]
if isinstance(value, models.Field):
return ModelFieldSerializer(value)
if isinstance(value, models.manager.BaseManager):
return ModelManagerSerializer(value)
if isinstance(value, Operation):
return OperationSerializer(value)
if isinstance(value, type):
return TypeSerializer(value)
# Anything that knows how to deconstruct itself.
if hasattr(value, 'deconstruct'):
return DeconstructableSerializer(value)
# Unfortunately some of these are order-dependent.
if isinstance(value, frozenset):
return FrozensetSerializer(value)
if isinstance(value, list):
return SequenceSerializer(value)
if isinstance(value, set):
return SetSerializer(value)
if isinstance(value, tuple):
return TupleSerializer(value)
if isinstance(value, dict):
return DictionarySerializer(value)
if enum and isinstance(value, enum.Enum):
return EnumSerializer(value)
if isinstance(value, datetime.datetime):
return DatetimeSerializer(value)
if isinstance(value, datetime.date):
return DateSerializer(value)
if isinstance(value, datetime.time):
return TimeSerializer(value)
if isinstance(value, datetime.timedelta):
return TimedeltaSerializer(value)
if isinstance(value, SettingsReference):
return SettingsReferenceSerializer(value)
if isinstance(value, float):
return FloatSerializer(value)
if isinstance(value, six.integer_types + (bool, type(None))):
return BaseSimpleSerializer(value)
if isinstance(value, six.binary_type):
return ByteTypeSerializer(value)
if isinstance(value, six.text_type):
return TextTypeSerializer(value)
if isinstance(value, decimal.Decimal):
return DecimalSerializer(value)
if isinstance(value, functools.partial):
return FunctoolsPartialSerializer(value)
if isinstance(value, (types.FunctionType, types.BuiltinFunctionType, types.MethodType)):
return FunctionTypeSerializer(value)
if isinstance(value, collections.Iterable):
return IterableSerializer(value)
if isinstance(value, (COMPILED_REGEX_TYPE, RegexObject)):
return RegexSerializer(value)
raise ValueError(
"Cannot serialize: %r\nThere are some values Django cannot serialize into "
"migration files.\nFor more, see https://docs.djangoproject.com/en/%s/"
"topics/migrations/#migration-serializing" % (value, get_docs_version())
)