使用`settings/dev.py`而不是`settings.py`运行在Django中执行模型查询的独立脚本

Question

注意settings/dev.py代替一个settings.py文件和以下Django(1.4.3)项目script.py中的my_appin:

.
??? my_project
?   ??? my_app
?   ?   ??? __init__.py
?   ?   ??? models.py
?   ?   ??? tests.py
?   ?   ??? views.py
?   ?   ??? script.py
?   ??? __init__.py
?   ??? settings
?   ?   ??? dev.py
?   ?   ??? __init__.py
?   ?   ??? prod.py
?   ??? urls.py
?   ??? wsgi.py
??? manage.py
??? requirements.txt

当我只有一个settings.py文件代替settings文件夹时,我能够运行以下脚本而没有任何错误:

script.py:

###################################################################
# set up for making it possible to run a model query from my script. 
###################################################################
import os
import sys
sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), os.path.pardir)))
from django.core.management import setup_environ
import settings
setup_environ(settings)
####################################################################  
from my_app.models import MyModel

all_entries = MyModel.objects.all()

顺便说一句,我得到了在第二种方法这篇文章中,我的设置是几线长,因为我script.py是在my_app文件夹中,而不是直接下my_project文件夹.

因为我现在用settings/dev.py instead的settings.py我改变了我设置的最后两行我的脚本为以下内容:

import settings.dev
import setup_environ(settings.dev)

但是,当我现在运行我的脚本时,我收到此错误:

Traceback (most recent call last):
  File "my_script.py", line 12, in <module>
    all_entries = MyModel.objects.all()
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/manager.py", line 131, in get
    return self.get_query_set().get(*args, **kwargs)
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/query.py", line 358, in get
    clone = self.filter(*args, **kwargs)
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/query.py", line 624, in filter
    return self._filter_or_exclude(False, *args, **kwargs)
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/query.py", line 642, in _filter_or_exclude
    clone.query.add_q(Q(*args, **kwargs))
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1250, in add_q
    can_reuse=used_aliases, force_having=force_having)
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1122, in add_filter
    process_extras=process_extras)
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/sql/query.py", line 1304, in setup_joins
    field, model, direct, m2m = opts.get_field_by_name(name)
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/options.py", line 311, in get_field_by_name
    cache = self.init_name_map()
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/options.py", line 341, in init_name_map
    for f, model in self.get_all_related_m2m_objects_with_model():
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/options.py", line 429, in get_all_related_m2m_objects_with_model
    cache = self._fill_related_many_to_many_cache()
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/options.py", line 443, in _fill_related_many_to_many_cache
    for klass in get_models(only_installed=False):
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/loading.py", line 181, in get_models
    self._populate()
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/loading.py", line 64, in _populate
    self.load_app(app_name, True)
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/db/models/loading.py", line 86, in load_app
    app_module = import_module(app_name)
  File "/home/my_username/.virtualenvs/my_project/local/lib/python2.7/site-packages/django/utils/importlib.py", line 35, in import_module
    __import__(name)
ImportError: No module named my_project.my_app

为什么会出现此错误？如何在Django中运行我的脚本settings/dev.py而不是settings.py？

Answer 1

如果你想在django环境中运行一个脚本,那么最简单的方法是创建一个./manage.py子命令,就像这样

from django.core.management.base import BaseCommand
from my_app.models import MyModel

class Command(BaseCommand):
    help = 'runs your code in the django environment'

    def handle(self, *args, **options):
        all_entries = MyModel.objects.all()
        for entry in all_entries:
            self.stdout.write('entry "%s"' % entry)

这些文档非常有助于解释这一点.

但是,您可以指定要使用的设置文件

$ django-admin.py runserver --settings=settings.dev

dev然而,这将使用设置运行测试服务器,我担心你的问题比简单的问题更深入.我不建议更改manage.py文件,因为这可能导致不一致和未来的麻烦.

另请注意,dev.py如果要执行此操作,则应该是完整的设置文件.我个人会推荐这样的结构:

|-settings
|    |- __init__.py
|    |- base.py
|    |- dev.py
|    |- prod.py

并保留你的所有常规设置,base.py并将你的第一行更改dev.py为类似的东西

# settings/dev.py
from .base import *

DEBUG = True
...

编辑

如果您只是想测试一下,为什么不试试

$ ./manage.py shell

或者使用开发设置

$ django-admin.py shell --settings=settings.dev

因为这将为您设置所有OS环境变量,settings.py然后您可以测试/调试

>>> from my_app.models import MyModel
>>> all_entries = MyModel.objects.all()
>>> for entry in all_entries:
...   print entry