我创建了自己的自定义models.TextField子类，它将类作为其值并将这些值编码为数据库中给定类的CODE属性。所有这一切到目前为止都在工作，但我想使用Django-reversion，它会对模型进行序列化，并在每次更改时将模型保存在版本表中。我正在将此用于我的申请审核目的。
Reversion无法序列化我分配给自定义字段的值，声称它们不可序列化。如何为我的对象定义序列化方法？我不能只定义一个DjangoJSONEncoder子类（Django默认用于序列化的类），因为我无法控制调用其serialize方法的代码，因为它是Django-reversion的一部分。这是堆栈跟踪，最终在Python的默认json编码器中失败：
ERROR: Could not save initial version for AccessCircuitRTTicket 3.
Traceback (most recent call last):
File "./manage.py", line 12, in <module>
execute_from_command_line(sys.argv)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line
utility.execute()
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/django/core/management/base.py", line 242, in run_from_argv
self.execute(*args, **options.__dict__)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/django/core/management/base.py", line 285, in execute
output = self.handle(*args, **options)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/reversion/management/commands/createinitialrevisions.py", line 87, in handle
self.create_initial_revisions(app, model_class, comment, batch_size, verbosity)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/reversion/management/commands/createinitialrevisions.py", line 123, in create_initial_revisions
default_revision_manager.save_revision((obj,), comment=comment)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/reversion/revisions.py", line 430, in save_revision
for obj in objects
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/reversion/revisions.py", line 430, in <genexpr>
for obj in objects
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/reversion/revisions.py", line 108, in get_version_data
"serialized_data": self.get_serialized_data(obj),
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/reversion/revisions.py", line 91, in get_serialized_data
fields = list(self.get_fields_to_serialize()),
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/django/core/serializers/__init__.py", line 122, in serialize
s.serialize(queryset, **options)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/django/core/serializers/base.py", line 58, in serialize
self.end_object(obj)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/django/core/serializers/json.py", line 52, in end_object
cls=DjangoJSONEncoder, **self.json_kwargs)
File "/usr/lib/python2.7/json/__init__.py", line 181, in dump
for chunk in iterable:
File "/usr/lib/python2.7/json/encoder.py", line 427, in _iterencode
for chunk in _iterencode_dict(o, _current_indent_level):
File "/usr/lib/python2.7/json/encoder.py", line 401, in _iterencode_dict
for chunk in chunks:
File "/usr/lib/python2.7/json/encoder.py", line 401, in _iterencode_dict
for chunk in chunks:
File "/usr/lib/python2.7/json/encoder.py", line 435, in _iterencode
o = _default(o)
File "/home/sgalbraith/.python_virtualenvs/unleash/local/lib/python2.7/site-packages/django/core/serializers/json.py", line 104, in default
return super(DjangoJSONEncoder, self).default(o)
File "/usr/lib/python2.7/json/encoder.py", line 177, in default
raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <class 'console.broadband.enumerations.ProvisioningTicket'> is not JSON serializable
对LazyEncoder的定义及其前面的文本中的答案here提出了一个模糊的建议。
答案 0 :(得分：1)
请注意，我所拥有的Django自定义字段具有类的值（即它们具有类型的类型）并且是EnumMember的子类，具有名为CODE的类成员，该成员提供其字符串表示。
我创建了以下模块 crm.serializers.json 并将设置中的SERIALIZATION_MODULES设置为
SERIALIZATION_MODULES = {
'json': 'crm.serializers.json',
}
crm.serializers.json代码如下：
# Avoid shadowing the standard library json module
from __future__ import absolute_import
from django.core.serializers.json import DjangoJSONEncoder, Serializer, \
Deserializer as DjangoDeserializer
from django.utils.encoding import force_text
from crm.enum import EnumMember
import json
####################################################################################################
#
# Extension of Django serialization capability so that apps such as Django-reversion can deal
# with custom fields.
#
####################################################################################################
class Serializer(Serializer):
# Override
# This is a copy paste of the superclass method, but with cls=ExtendedJSONEncoder
# instead of cls=DjangoJSONEncoder below
def end_object(self, obj):
# self._current has the field data
indent = self.options.get("indent")
if not self.first:
self.stream.write(",")
if not indent:
self.stream.write(" ")
if indent:
self.stream.write("\n")
json.dump(self.get_dump_object(obj), self.stream,
cls=ExtendedJSONEncoder, **self.json_kwargs)
self._current = None
pass
Deserializer = DjangoDeserializer
class ExtendedJSONEncoder(DjangoJSONEncoder):
"""
Provides default serialization for custom data types as well as default ones.
"""
def default(self, obj):
if type(obj) == type and issubclass(obj, EnumMember):
return obj.CODE
else:
return super(ExtendedJSONEncoder, self).default(obj)
答案 1 :(得分：0)
不能肯定地说，因为我看不到您的TextField子类，但是
value_to_string(self, obj)
在序列化框架中使用，可以重写Field类的此方法。
像这样
def value_to_string(self, obj):
return self.value_from_object(obj.CODE)
要进行反序列化，请确保您的to_python(self, value)工作正常