Django:导入模型有效，之后立即导入其实例

Question

我正在使用此仓库：https://github.com/intelligenttrading/data

供参考，我相信这两行的后者是有罪的一行：

from apps.channel.models import ExchangeData
from apps.channel.models.exchange_data import POLONIEX

页面有指令。我几乎已经走到最后了，然后运行了：

python manage.py poloniex_polling

供参考，这是poloniex_polling.py的代码：

import json
import logging
import schedule
import time
from django.core.management.base import BaseCommand
from requests import get, RequestException
from apps.channel.models import ExchangeData
from apps.channel.models.exchange_data import POLONIEX
logger = logging.getLogger(__name__)

class Command(BaseCommand):
    help = "Polls data from Poloniex every 1 minute"
    def handle(self, *args, **options):
        logger.info("Getting ready to poll Poloniex...")
        schedule.every(1).minutes.do(poll_latest_poloniex_data)
        keep_going=True
        while keep_going:
            try:
                schedule.run_pending()
                time.sleep(1)
            except Exception as e:
                logger.debug(str(e))
                logger.info("Poloniex polling shut down.")
                keep_going = False

def poll_latest_poloniex_data():
    try:
        logger.info("polling for Poloniex data...")
        req = get('https://poloniex.com/public?command=returnTicker')
        poloniex_data_point = ExchangeData.objects.create(
            source=POLONIEX,
            data=req.json(), # the exact json from the request data
            timestamp=time.time() # now
        )
        logger.info("Saving Poloniex data...")
    except RequestException:
        return 'Error to collect data from Poloniex'

运行python manage.py poloniex_polling时，我得到：

INFO:settings:Deployment environment detected: LOCAL
INFO:settings:Importing vendor_services_settings
INFO:settings:LOCAL environment detected. Importing local_settings.py
Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/home/cerulean/.virtualenvs/ITF/lib/python3.6/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/cerulean/.virtualenvs/ITF/lib/python3.6/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/cerulean/.virtualenvs/ITF/lib/python3.6/site-packages/django/core/management/__init__.py", line 224, in fetch_command
    klass = load_command_class(app_name, subcommand)
  File "/home/cerulean/.virtualenvs/ITF/lib/python3.6/site-packages/django/core/management/__init__.py", line 36, in load_command_class
    module = import_module('%s.management.commands.%s' % (app_name, name))
  File "/home/cerulean/.virtualenvs/ITF/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/cerulean/Code/ITF/data-fork/data/apps/channel/management/commands/poloniex_polling.py", line 10, in <module>
    from apps.channel.models.exchange_data import POLONIEX
ImportError: cannot import name 'POLONIEX'

似乎

from apps.channel.models.exchange_data import POLONIEX

在poloniex_polling.py中，试图在实例化之前试图导入一个名为poloniex的模型。

根据我努力使该应用程序上升和运行的经验，这通常是一个越来越高的问题。也许这是一个未运行的数据库？为了机智，我正在运行PostgreSQL Server作为服务。数据库中有数据，Localhost：8000正在工作。

这是模型文件夹中的Exchange_data.py：

from django.db import models
from django.contrib.postgres.fields import JSONField
from unixtimestampfield.fields import UnixTimeStampField

    class ExchangeData(models.Model):
        source = models.CharField(max_length=128)
        data = JSONField(default="")
        timestamp = UnixTimeStampField(null=False)

        # MODEL PROPERTIES
        # MODEL FUNCTIONS

非常感谢。

Answer 1

这显然是该命令的错误。从代码中可以看到，该模型文件不包含名为poloniex的对象。没有丢失的数据库可以解决此问题。

您的经验"在此应用程序中挣扎"可能取决于它不起作用的事实。

Answer 2

我弄清楚了。我在从相关存储库中获取的模型中添加了代码，并修复了错误：

from settings import SOURCE_CHOICES
(POLONIEX, BITTREX) = list(range(2))
SOURCE_CHOICES = (
    (POLONIEX, 'poloniex'),
    (BITTREX, 'bittrex'),
)

现在，poloniex对象存在。