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python - Is this a circular import?

问题描述

(follow up to:

The included URLconf 'appName.urls' does not appear to have any patterns in it )

My site project directory looks like:

enter image description here

(cryptocurrency, cryptoboard, cryptousers, frontend, leads, polls are apps).

I think that:

setup_debug_table.py(cryptocurrency):

import random
from datetime import timedelta

from django.utils.datetime_safe import datetime
from django.utils.timezone import now

from .coins_constants import NO_OF_DAYS, NO_OF_HOURS, coins_ids
from .models import Currency, Transaction, DebugConf
from cryptoboard.cryptousers.models import CryptoUser

def init_debug_tables():
    # Check if debug table has already been initialized
    debug_conf = DebugConf.objects.all()
    if debug_conf.exists():
        return

    # Clear tables
    CryptoUser.objects.all().delete()
    Currency.objects.all().delete()
    Transaction.objects.all().delete()

specifically, line:

from cryptoboard.cryptousers.models import CryptoUser

is what's causing the error (CryptoUser is a model in a different app (cryptousers)), somewhat similar to this answer.

models.py, on the other hand, looks fine:

models.py(cryptocurrency)

from django.db import models

class DebugConf(models.Model):
    is_setup = models.BooleanField(default=False)
    debug_setup_date = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.is_setup


class Currency(models.Model):
    currency_name = models.CharField(max_length=100, unique=True)
    currency_value = models.FloatField()
    currency_value_in_dollars = models.FloatField()
    currency_value_in_dollars_date = models.DateTimeField()

    def __str__(self):
        return self.currency_name


class Transaction(models.Model):
    transaction_type = models.CharField(max_length=200)
    transaction_amount = models.FloatField()
    transaction_date = models.DateTimeField(auto_now_add=True)

    transaction_currency = models.ForeignKey(Currency, on_delete=models.CASCADE)
    transaction_buyer = models.ForeignKey('cryptousers.CryptoUser', related_name='transaction_buyer', on_delete=models.CASCADE)
    transaction_seller = models.ForeignKey('cryptousers.CryptoUser', related_name='transaction_seller', on_delete=models.CASCADE)

    def __str__(self):
         return self.transaction_currency

Stack trace:

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

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\urls\resolvers.py", line 591, in url_patterns
    iter(patterns)
TypeError: 'module' object is not iterable

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\dev\AppData\Local\Programs\Python\Python36\lib\threading.py", line 916, in _bootstrap_inner
    self.run()
  File "C:\Users\dev\AppData\Local\Programs\Python\Python36\lib\threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\utils\autoreload.py", line 53, in wrapper
    fn(*args, **kwargs)
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\core\management\commands\runserver.py", line 118, in inner_run
    self.check(display_num_errors=True)
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\core\management\base.py", line 396, in check
    databases=databases,
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\core\checks\registry.py", line 70, in run_checks
    new_errors = check(app_configs=app_configs, databases=databases)
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\core\checks\urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\core\checks\urls.py", line 23, in check_resolver
    return check_method()
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\urls\resolvers.py", line 408, in check
    for pattern in self.url_patterns:
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\utils\functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "C:\Users\dev\.virtualenvs\crypto-currency-board-2JkLYBxc\lib\site-packages\django\urls\resolvers.py", line 598, in url_patterns
    raise ImproperlyConfigured(msg.format(name=self.urlconf_name)) from e
django.core.exceptions.ImproperlyConfigured: The included URLconf 'cryptoboard.urls' does not appear to have any patterns in it. If you see valid patterns in the file then the issue is probably caused by a circular import.

Is the import of a model from a different app circular?

标签： pythonpython-3.xdjango

解决方案

我认为应该只是：

from cryptousers.models import CryptoUser

如果您好奇，这里有一篇很好的文章解释循环导入： https ://stackabuse.com/python-circular-imports/

只要模型不通过彼此定义自己，从另一个应用程序导入模型就可以了。

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