对Django还是一个新手，请耐心等待。
我正在尝试遵循Django示例https://docs.djangoproject.com/en/2.2/ref/contrib/contenttypes/。
我正在尝试使用tests.py为学生1创建笔记。
这是tests.py：
from django.test import TestCase
from gsndb.models import *
from django.contrib.contenttypes.models import ContentType
from django.contrib.auth.models import User
# Create your tests here.
student = Student.objects.get(id=4)
text = "The student is content"
user = User.objects.get(id=2)
new_note = Note(text=text, content_object = student, user = user)
new_note.save()
我希望它为学生1创建一个笔记。但是，当我运行测试时，出现此错误：
Object of type 'Student' is not JSON serializable
这是回溯：
Environment:
Request Method: GET
Request URL: http://localhost/gsndb/note/
Django Version: 2.1.7
Python Version: 3.6.8
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'corsheaders',
'rest_framework',
'user_app.apps.UserAppConfig',
'gsndb.apps.GsndbConfig']
Installed Middleware:
['corsheaders.middleware.CorsMiddleware',
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware']
Traceback:
File "/usr/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
34. response = get_response(request)
File "/usr/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
156. response = self.process_exception_by_middleware(e, request)
File "/usr/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
154. response = response.render()
File "/usr/lib/python3.6/site-packages/django/template/response.py" in render
106. self.content = self.rendered_content
File "/usr/lib/python3.6/site-packages/rest_framework/response.py" in rendered_content
72. ret = renderer.render(self.data, accepted_media_type, context)
File "/usr/lib/python3.6/site-packages/djangorestframework_camel_case2/render.py" in render
9. **kwargs)
File "/usr/lib/python3.6/site-packages/rest_framework/renderers.py" in render
107. allow_nan=not self.strict, separators=separators
File "/usr/lib/python3.6/site-packages/rest_framework/utils/json.py" in dumps
28. return json.dumps(*args, **kwargs)
File "/usr/lib/python3.6/json/__init__.py" in dumps
238. **kw).encode(obj)
File "/usr/lib/python3.6/json/encoder.py" in encode
199. chunks = self.iterencode(o, _one_shot=True)
File "/usr/lib/python3.6/json/encoder.py" in iterencode
257. return _iterencode(o, 0)
File "/usr/lib/python3.6/site-packages/rest_framework/utils/encoders.py" in default
68. return super(JSONEncoder, self).default(obj)
File "/usr/lib/python3.6/json/encoder.py" in default
180. o.__class__.__name__)
Exception Type: TypeError at /gsndb/note/
Exception Value: Object of type 'Student' is not JSON serializable
这里是models.py
class Note(models.Model):
user = models.ForeignKey(
get_user_model(),
on_delete = models.PROTECT,
)
created = models.DateTimeField(default = timezone.now)
text = models.TextField()
# Below the mandatory fields for generic relation
content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
object_id = models.PositiveIntegerField()
content_object = GenericForeignKey('content_type','object_id')
class Student(models.Model):
current_school = models.ForeignKey(
"School",
null = True,
on_delete = models.PROTECT,
)
current_program = models.ForeignKey(
"Program",
null = True,
on_delete = models.PROTECT,
)
first_name = models.CharField(max_length = 35, blank=True)
last_name = models.CharField(max_length = 35, blank=True)
middle_name = models.CharField(max_length = 35, blank=True)
"""Establish choices for Gender"""
GENDER_CHOICES = (
("M", 'Male'),
("F", 'Female'),
("NB", 'NonBinary'),
)
gender = models.CharField(
max_length = 2,
blank = True,
choices = GENDER_CHOICES,
)
birth_date = models.DateField(null = True)
state_id = models.BigIntegerField(null = True)
"""Establish choices for Grade Year"""
GRADE_YEAR_CHOICES = (
(0, 'Kindergarten'),
(1, 'First Grade'),
(2, 'Second Grade'),
(3, 'Third Grade'),
(4, 'Fourth Grade'),
(5, 'Fifth Grade'),
(6, 'Sixth Grade'),
(7, 'Seventh Grade'),
(8, 'Eighth Grade'),
(9, 'Ninth Grade'),
(10, 'Tenth Grade'),
(11, 'Eleventh Grade'),
(12, 'Twelfth Grade'),
)
grade_year = models.SmallIntegerField(
choices = GRADE_YEAR_CHOICES,
null = True,
)
reason_in_program = models.TextField(blank=True)
notes = GenericRelation(Note)
这是serializers.py：
class NoteSerializer(serializers.ModelSerializer):
class Meta:
model = Note
fields = ("user",
"created",
"text",
"content_type",
"object_id",
"content_object")
class StudentSerializer(serializers.BaseSerializer):
def to_representation(self, student_obj):
notes = NoteSerializer(many = True)
notes_json = notes.data
return {
"current_school": student_obj.current_school.id,
"current_program": student_obj.current_program.id,
"first_name": student_obj.first_name,
"last_name": student_obj.last_name,
"middle_name": student_obj.middle_name,
"gender": student_obj.gender,
"birth_date": student_obj.birth_date,
"state_id": student_obj.state_id,
"grade_year": student_obj.grade_year,
"reason_in_program": student_obj.reason_in_program,
"notes": notes_json,
}
这是我的views.py：
class NoteList(generics.ListCreateAPIView):
queryset = Note.objects.all()
serializer_class = NoteSerializer
感谢您的时间！
答案 0 :(得分：1)
弄清楚了我的问题。在我看来。
我的观点是
class NoteSerializer(serializers.ModelSerializer):
class Meta:
model = Note
fields = ("user",
"created",
"text",
"content_type",
"object_id",
"content_object")
我需要删除“ content_object”，因为它不是JSON可序列化的。它需要看起来像这样：
class NoteSerializer(serializers.ModelSerializer):
class Meta:
model = Note
fields = ("user",
"created",
"text",
"content_type",
"object_id")
感谢所有帮助！