AttributeError: "QuerySet" doesn't have attribute 'model'

Question

I'm trying to create a basic django-rest-framework backend with mongoengine as a database. I have successfully made a basic list of entries which supports POST and behaves as needed with required fields.

However I encounter this bug with QuerySet not having attribute 'model'. Of what I've seen in the web - people get this kind of bug when putting a filtered collection in object. However in my case it is different(I believe). The error appears when I'm accessing /box/1 endpoint.

The source codes as below:

models.py:

from __future__ import unicode_literals

import datetime
from mongoengine import Document, connect, EmbeddedDocument, fields, DynamicDocument
from django.db import models

# Create your models here.
from mongoengine import signals

connect('yourdb', alias='default')

class GPS(EmbeddedDocument):
    lat = fields.FloatField(null=False, required=True)
    lon = fields.FloatField(null=False, required=True)


class PPM(EmbeddedDocument):
    time = fields.DateTimeField(default=datetime.datetime.now())
    value = fields.IntField(null=False, required=True)

    @classmethod
    def pre_save(cls, sender, document, **kwargs):
        document.time = datetime.datetime.now()


signals.pre_save.connect(PPM.pre_save, sender=PPM)

class BuyHistory(EmbeddedDocument):
    time = fields.DateTimeField(default=datetime.datetime.now())
    boxid = fields.StringField(max_length=128, null=False, required=True)
    username = fields.StringField(max_length=128, null=False, required=True)
    product = fields.StringField(max_length=128, null=False, required=True)
    amount = fields.IntField()

    @classmethod
    def pre_save(cls, sender, document, **kwargs):
        document.time = datetime.datetime.now()


signals.pre_save.connect(BuyHistory.pre_save, sender=BuyHistory)

class RecycleHistory(EmbeddedDocument):
    time = fields.DateTimeField(default=datetime.datetime.now())
    boxid = fields.StringField(max_length=128, null=False, required=True)
    username = fields.StringField(max_length=128, null=False, required=True)
    amount = fields.IntField()

    @classmethod
    def pre_save(cls, sender, document, **kwargs):
        document.time = datetime.datetime.now()


signals.pre_save.connect(RecycleHistory.pre_save, sender=RecycleHistory)

class Box(Document):
    boxid = fields.StringField(max_length=128, null=False, required=True)
    gps = fields.EmbeddedDocumentField(GPS, required=True)
    buy_history = fields.EmbeddedDocumentListField(BuyHistory, default='[]')
    recycle_history = fields.EmbeddedDocumentListField(RecycleHistory, default='[]')
    ppm_history = fields.EmbeddedDocumentListField(PPM, default='[]')

class User(Document):
    username = fields.StringField(max_length=128, null=False, required=True)
    rfid = fields.StringField(max_length=32, null=False, required=True)
    buy_history = fields.EmbeddedDocumentListField(BuyHistory)
    recycle_history = fields.EmbeddedDocumentListField(RecycleHistory)

serializers.py:

from rest_framework_mongoengine import serializers
from models import User, BuyHistory, Box, RecycleHistory, PPM

class UserSerializer(serializers.DocumentSerializer):
    class Meta:
        model = User
        fields = ('username', 'rfid', 'buy_history', 'recycle_history')


class PPMSerializer(serializers.DocumentSerializer):
    class Meta:
        model = PPM
        fields = ('time', 'value')


class BuyHistorySerializer(serializers.EmbeddedDocumentSerializer):
    class Meta:
        model = BuyHistory
        fields = ('time', 'boxid', 'username', 'product', 'amount')


class RecycleHistorySerializer(serializers.EmbeddedDocumentSerializer):
    class Meta:
        model = RecycleHistory
        fields = ('time', 'boxid', 'username', 'product', 'amount')


class BoxSerializer(serializers.DocumentSerializer):

    class Meta:
        model = Box
        fields = ('boxid', 'gps', 'buy_history', 'recycle_history', 'ppm_history')

views.py:

from models import User, Box
from serializers import UserSerializer, BoxSerializer
from rest_framework import generics
# Create your views here.


class BoxList(generics.ListCreateAPIView):
    queryset = Box.objects.all()
    serializer_class = BoxSerializer

class UserList(generics.ListCreateAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer


class BoxDetail(generics.RetrieveUpdateDestroyAPIView):
    queryset = Box.objects.all()
    serializer_class = BoxSerializer(partial=True)


class UserDetail(generics.RetrieveUpdateDestroyAPIView):
    queryset = User.objects.all()
    serializer_class = UserSerializer(partial=True)

urls.py:

from django.conf.urls import url
from django.contrib import admin
from server_api import views

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^box/$', views.BoxList.as_view()),
    url(r'^box/(?P<pk>[0-9]+)$', views.BoxDetail.as_view()),
    url(r'^user/$', views.UserList.as_view()),
]

settings.py:

import os

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/1.10/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '08v0)(rn8ae8%v9li=he7n9)50q5^wre8srx*m#0_idvcu=jew'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'rest_framework',
    'server_api.apps.ServerApiConfig'
]

MIDDLEWARE = [
    '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',
]

ROOT_URLCONF = 'pmi_pos_server_django.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'pmi_pos_server_django.wsgi.application'


# Database
# https://docs.djangoproject.com/en/1.10/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}


# Password validation
# https://docs.djangoproject.com/en/1.10/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/1.10/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/1.10/howto/static-files/

STATIC_URL = '/static/'

Versions:

Also, I would really appreciate if someone could suggest a very detailed tutorial about Django, I have read Django-Rest-Framework classic tutorial, quickstart and API-reference, however I still feel that information is not enough for me - if there's any good in-depth tutorial to be suggested - please do it.

EDIT 1:

Tracelog:

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/django/core/handlers/exception.py", line 39, in inner
    response = get_response(request)
  File "/usr/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/usr/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
    return view_func(*args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/django/views/generic/base.py", line 68, in view
    return self.dispatch(request, *args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/rest_framework/views.py", line 477, in dispatch
    response = self.handle_exception(exc)
  File "/usr/local/lib/python2.7/site-packages/rest_framework/views.py", line 437, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/usr/local/lib/python2.7/site-packages/rest_framework/views.py", line 474, in dispatch
    response = handler(request, *args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/rest_framework/generics.py", line 283, in get
    return self.retrieve(request, *args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/rest_framework/mixins.py", line 56, in retrieve
    instance = self.get_object()
  File "/usr/local/lib/python2.7/site-packages/rest_framework/generics.py", line 97, in get_object
    obj = get_object_or_404(queryset, **filter_kwargs)
  File "/usr/local/lib/python2.7/site-packages/rest_framework/generics.py", line 20, in get_object_or_404
    return _get_object_or_404(queryset, *filter_args, **filter_kwargs)
  File "/usr/local/lib/python2.7/site-packages/django/shortcuts.py", line 92, in get_object_or_404
    except queryset.model.DoesNotExist:
AttributeError: 'QuerySet' object has no attribute 'model'

You should have provided your trace log

Sardorbek Imomaliev
– Sardorbek Imomaliev

2016-11-28 05:11:17 +00:00
Commented Nov 28, 2016 at 5:11 — Sardorbek Imomaliev
– Sardorbek Imomaliev, Commented Nov 28, 2016 at 5:11

Sardorbek Imomaliev · Accepted Answer · 2016-11-28 06:11:51Z

1

You are doing this

serializer_class = BoxSerializer(partial=True)

this is invalid code, because you are instantiating serializer here, so serializer instance will be stored in serializer_class variable not a class

answered Nov 28, 2016 at 6:11

Sardorbek Imomaliev

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2 Comments

Constantine Samoilenko Over a year ago

Thank you for advice. I fixed it, however the bug still reproduces. However regarding serializer instantiation - then where do I need to declare partial=True? I want to do it in order to allow partial updates on nested lists because they are meant to accumulate data, and as I read with classic UPDATE I have to provide a new object to completely change the existing one.

Sardorbek Imomaliev Over a year ago

@ConstantineSamoilenko there is get_serializer method You can set it there

Constantine Samoilenko · Accepted Answer · 2016-11-28 09:45:28Z

1

Ok, I have found a problem - I changed the generics import - now I'm using from rest_framework_mongoengine import generics. I assume the conflict was that it couldn't find model parameter of queryset because it was not in default database from config.

answered Nov 28, 2016 at 9:45

Constantine Samoilenko

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