背景
Djangoのバージョンを1.11.1から2.2へあげると、バイト文字列で保存したTextFieldsの値が取り出した時に、
b'...'と皮まで保存されるようになっていた。
結論
- decodeを使ってstring型に変換していたのがstr()を使ってstring型へ変更するようになっていた。
- str()を使うと改行文字がエスケープされたり、b''まで文字列に含まれたりする。
参考
version 1.11.1
- s = s.decode(encoding, errors)
- https://docs.djangoproject.com/ja/1.11/_modules/django/db/models/fields/
django.db.models.fields.py
from django.utils.encoding import (
force_bytes, force_text, python_2_unicode_compatible, smart_text,
)
class TextField(Field):
description = _("Text")
def to_python(self, value):
if isinstance(value, six.string_types) or value is None:
return value
return force_text(value)
django.utils.encoding.py
def force_text(s, encoding='utf-8', strings_only=False, errors='strict'):
"""
Similar to smart_text, except that lazy instances are resolved to
strings, rather than kept as lazy objects.
If strings_only is True, don't convert (some) non-string-like objects.
"""
# Handle the common case first for performance reasons.
if issubclass(type(s), six.text_type):
return s
if strings_only and is_protected_type(s):
return s
try:
if not issubclass(type(s), six.string_types):
if six.PY3:
if isinstance(s, bytes):
s = six.text_type(s, encoding, errors)
else:
s = six.text_type(s)
elif hasattr(s, '__unicode__'):
s = six.text_type(s)
else:
s = six.text_type(bytes(s), encoding, errors)
else:
# Note: We use .decode() here, instead of six.text_type(s, encoding,
# errors), so that if s is a SafeBytes, it ends up being a
# SafeText at the end.
s = s.decode(encoding, errors)
except UnicodeDecodeError as e:
if not isinstance(s, Exception):
raise DjangoUnicodeDecodeError(s, *e.args)
else:
# If we get to here, the caller has passed in an Exception
# subclass populated with non-ASCII bytestring data without a
# working unicode method. Try to handle this without raising a
# further exception by individually forcing the exception args
# to unicode.
s = ' '.join(force_text(arg, encoding, strings_only, errors)
for arg in s)
return s
version 2.2
django.db.models.fields.py
class TextField(Field):
description = _("Text")
def to_python(self, value):
if isinstance(value, str) or value is None:
return value
return str(value)