drf框架里面的json字符串field改版，主要是针对model字段为text

serializer_jsonfield.py

import json
from rest_framework.fields import Field
from django.utils.translation import gettext_lazy as _


class MyJSONField(Field):
    default_error_messages = {
        'invalid': _('Value must be valid JSON.')
    }

    def __init__(self, *args, **kwargs):
        self.ensure_ascii = kwargs.pop('ensure_ascii', True)
        self.encoder = kwargs.pop('encoder', None)
        super().__init__(*args, **kwargs)

    def to_internal_value(self, data):
        if data is None:
            return None
        try:
            return json.dumps(data, cls=self.encoder, ensure_ascii=self.ensure_ascii)
        except (TypeError, ValueError):
            self.fail('invalid')
        return data

    def to_representation(self, value):
        if value is None:
            return None
        value = json.loads(value, cls=self.encoder)
        return value