Django集成Djongo+MongoDB时遇ImportError：无法导入djongo_access_url

错误现象 #

在Django服务器中使用Djongo搭配MongoDB时，导入from djongo import transaction触发以下错误：

Watching for file changes with StatReloader
Performing system checks...

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/usr/lib/python3.10/threading.py", line 1009, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.10/threading.py", line 946, in run
    self._target(*self._args, **self._kwargs)
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/utils/autoreload.py", line 53, in wrapper
    fn(*args, **kwargs)
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/core/management/commands/runserver.py", line 118, in inner_run
    self.check(display_num_errors=True)
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/core/management/base.py", line 392, in check
    all_issues = checks.run_checks(
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/core/checks/registry.py", line 70, in run_checks
    new_errors = check(app_configs=app_configs, databases=databases)
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/core/checks/urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/core/checks/urls.py", line 23, in check_resolver
    return check_method()
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/urls/resolvers.py", line 408, in check
    for pattern in self.url_patterns:
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/urls/resolvers.py", line 589, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/urls/resolvers.py", line 582, in urlconf_module
    return import_module(self.urlconf_name)
  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/cchilders/projects/stocks_backend/dividends_project/urls.py", line 23, in <module>
    path('users/', include('users.urls', namespace='users')),
  File "/home/cchilders/.local/lib/python3.10/site-packages/django/urls/conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/cchilders/projects/stocks_backend/users/urls.py", line 3, in <module>
    from . import views
  File "/home/cchilders/projects/stocks_backend/users/views.py", line 10, in <module>
    from djongo import transaction
  File "/home/cchilders/.local/lib/python3.10/site-packages/djongo/transaction.py", line 2, in <module>
    from djongo import djongo_access_url
ImportError: cannot import name 'djongo_access_url' from 'djongo' (/home/cchilders/.local/lib/python3.10/site-packages/djongo/__init__.py)

在IPython中也能复现该错误：

IPython 8.4.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import djongo

In [2]: from djongo import transaction
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
Input In [2], in <cell line: 1>()
----> 1 from djongo import transaction

File ~/.local/lib/python3.10/site-packages/djongo/transaction.py:2, in <module>
      1 from djongo.exceptions import NotSupportedError
----> 2 from djongo import djongo_access_url
      4 print(f'This version of djongo does not support transactions. Visit {djongo_access_url}')
      5 raise NotSupportedError('transactions')

ImportError: cannot import name 'djongo_access_url' from 'djongo' (/home/cchilders/.local/lib/python3.10/site-packages/djongo/__init__.py)

相关代码 #

users/views.py #

from django.shortcuts import render
from django.http import HttpResponse
from django.views.decorators.csrf import csrf_exempt

import json

from helpers.view_functions import parse_request_body
from .models import UserProfile

from djongo import transaction


@csrf_exempt
def get_user_profile(request, user_id):
    # pass
    if request.method == 'GET':
        with transaction.atomic():
            profile, created = UserProfile.objects.get_or_create(user_id=user_id)
        if created:
            profile.user_id = user_id
            profile.searches = [
                {'search_term': 'hd'},
                {'search_term': 'wba'},
            ]
            profile.display_settings = [
                {'setting_name': 'showYieldChange', 'visible': True},
                {'setting_name': 'showAllDividends', 'visible': True},
            ]
            profile.save()
            print("user saved in db")
        user = UserProfile.objects.get(user_id=user_id)


        data = {
            'user_id': user.user_id,
            'searches': user.searches,
            'display_settings': user.display_settings
        }
        json_data = json.dumps(data)
        return HttpResponse({json_data}, content_type='application/json')

    if request.method == 'POST':
        body = parse_request_body(request)
        searches = body['searches']
        searches_objects = [{'search_term': x} for x in searches]
        print("New searches for user {user_id}".format(user_id=user_id))
        print(searches_objects)
        user = UserProfile.objects.get(user_id=user_id)
        user.searches = searches_objects
        user.display_settings = body['display_settings']
        user.save()
        return HttpResponse("it worked")

users/urls.py #

from django.urls import path

from . import views

app_name = 'dividends'
urlpatterns = [
    path('<str:user_id>', views.get_user_profile, name='get_user_profile'),
]

requirements.txt #

bs4
django==3.1.12
django-cors-headers
djongo
gunicorn
html5lib
pymongo==3.12.3
python-decouple
yfinance

users/models.py #

from djongo import models


class RecentSearch(models.Model):
    search_term = models.CharField(max_length=100)

    class Meta:
        abstract = True


class DisplaySetting(models.Model):
    setting_name = models.CharField(max_length=150)
    visible = models.BooleanField()

    class Meta:
        abstract = True


class UserProfile(models.Model):
    user_id = models.CharField(max_length=255, unique=True)
    searches = models.ArrayField(model_container=RecentSearch, null=True)
    display_settings = models.ArrayField(model_container=DisplaySetting, null=True)

    objects = models.DjongoManager()

问题分析与解决方案 #

原因 #

从transaction.py的代码可以看到，即使导入成功，该版本的Djongo也会直接抛出NotSupportedError，明确说明不支持事务。当前错误是因为transaction.py尝试导入的djongo_access_url变量在Djongo的__init__.py中不存在，属于版本内部的代码错误。

解决步骤 #

1. 移除事务相关代码

   • 删除views.py中的from djongo import transaction导入语句
   • 删掉with transaction.atomic():代码块，直接执行profile, created = UserProfile.objects.get_or_create(user_id=user_id)（MongoDB对唯一键的单文档操作本身具备原子性）

   修改后的get_user_profile函数关键部分：

   @csrf_exempt
   def get_user_profile(request, user_id):
       if request.method == 'GET':
           profile, created = UserProfile.objects.get_or_create(user_id=user_id)
           if created:
               profile.searches = [
                   {'search_term': 'hd'},
                   {'search_term': 'wba'},
               ]
               profile.display_settings = [
                   {'setting_name': 'showYieldChange', 'visible': True},
                   {'setting_name': 'showAllDividends', 'visible': True},
               ]
               profile.save()
               print("user saved in db")
           # 后续逻辑不变
   

2. 可选：调整Djongo版本
   如果需要尝试其他版本的Djongo，可在requirements.txt中指定兼容版本，比如：

   djongo==1.3.6
   

   注意要确保版本与Django 3.1.12兼容，且Djongo对MongoDB事务的支持依赖于MongoDB副本集，单实例MongoDB本身不支持事务。

内容的提问来源于stack exchange，提问作者codyc4321