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Django在同一模型内引用多个域,错误不带引号

manytomanyfield syntax django python

myaddresstoday · 技术社区 · 7 年前

https://docs.djangoproject.com/en/1.11/topics/db/examples/many_to_many/

所以我的代码基于这个文档,我遇到了一个错误。

from django.db import models

class Gift(models.Model):
    name = models.CharField(
      max_length=120, unique=True, help_text='Enter the gift item name'
    )
    # skipping to the ManyToMany ....
    genre = models.ManyToManyField(Category)

class Category(models.Model):
    # skipping stuff like CATEGORIES ...
    type = models.IntegerField(
      primary_key   = True, choices = CATEGORIES, default = EVENT,
    )
    description = models.CharField(max_length=500, null=True, blank=True)

我收到此错误

Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/.../gifting_db/lib/python3.6/site-packages/django/core/management/__init__.py", line 363, in execute_from_command_line
    utility.execute()
  File "/.../gifting_db/lib/python3.6/site-packages/django/core/management/__init__.py", line 337, in execute
    django.setup()
  File "/.../gifting_db/lib/python3.6/site-packages/django/__init__.py", line 27, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/.../gifting_db/lib/python3.6/site-packages/django/apps/registry.py", line 108, in populate
    app_config.import_models()
  File "/.../gifting_db/lib/python3.6/site-packages/django/apps/config.py", line 202, in import_models
    self.models_module = import_module(models_module_name)
  File "/.../gifting_db/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 978, in _gcd_import
  File "<frozen importlib._bootstrap>", line 961, in _find_and_load
  File "<frozen importlib._bootstrap>", line 950, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 205, in _call_with_frames_removed
  File "/.../gifting_db/gifting/gifts/models.py", line 5, in <module>
    class Gift(models.Model):
  File "/.../gifting_db/gifting/gifts/models.py", line 20, in Gift
    category    = models.ManyToManyField(Category)
NameError: name 'Category' is not defined

https://docs.djangoproject.com/en/1.11/topics/db/examples/many_to_many/ 在“出版物”和“文章”之间。如果有什么不同的话,我想我是把“Category”作为字符串放进去的,而不是作为对Category对象的引用?

genre = models.ManyToManyField('Category')

2 回复 | 直到 7 年前

Raj Subit 7 年前

你需要定义 Category Gift

from django.db import models


class Category(models.Model):
    # skipping stuff like CATEGORIES ...
    type = models.IntegerField(
    primary_key = True, choices=CATEGORIES, default=EVENT)
    description = models.CharField(max_length=500, null=True, blank=True)


class Gift(models.Model):
    name = models.CharField(max_length=120, unique=True, help_text='Enter the gift item name'
    )
    # skipping to the ManyToMany ....
    genre = models.ManyToManyField(Category)

或 use quotes

from django.db import models


class Gift(models.Model):
    name = models.CharField(max_length=120, unique=True, help_text='Enter the gift item name'
    )
    # skipping to the ManyToMany ....
    genre = models.ManyToManyField('Category')


class Category(models.Model):
    # skipping stuff like CATEGORIES ...
    type = models.IntegerField(primary_key=True, choices=CATEGORIES, default=EVENT,)
    description = models.CharField(max_length=500, null=True, blank=True

Cory Madden 7 年前

你的问题是 Category 直到之后才定义 Gift 。如果您想使用它而不使用引号,则需要放置在上面。否则,报价工作正常,并提供相同的功能。

https://docs.djangoproject.com/en/dev/ref/models/fields/#foreignkey

如果您需要在尚未建立的模型上创建关系对象本身: