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你好我创建了两个模型，第二个必须先使用它，例如第一个模型是产品，第二个是包含少量产品的商店。Django如何添加外键 - 多选
from django.db import models
# Create your models here.
class Product(models.Model):
name = models.CharField("name", max_length=40)
price = models.FloatField("price")
def __unicode__(self):
return self.name
class Shop(models.Model):
product = models.ForeignKey(Product, null = True)
name = models.CharField("shopname", max_length=40)
salary = models.FloatField("salary")
def __unicode__(self):
return self.name
这是好的开始吗？我想创造一些能够给Shop.model增加许多Product.model的可能性。如何创建它？
而第二个问题是 - 现在，当我点击
蟒蛇manage.py迁移homebudget
我有信息
(venv) C:\Users\noname\nowe\budget>python manage.py makemigrations homebudget
Migrations for 'homebudget':
0011_auto_20150513_1817.py:
- Alter field price on product
- Alter field name on product
- Alter field name on shop
- Alter field salary on shop
(venv) C:\Users\noname\nowe\budget>python manage.py migrate homebudget
Operations to perform:
Apply all migrations: homebudget
Running migrations:
Rendering model states... DONE
Applying homebudget.0002_shop_product...Traceback (most recent call las
t):
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\core\management\__init_
_.py", line 338, in execute_from_command_line
utility.execute()
File "C:\Users\noname\nowe\venv\lib\site-packages\django\core\management\__init_
_.py", line 330, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\core\management\base.py
", line 390, in run_from_argv
self.execute(*args, **cmd_options)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\core\management\base.py
", line 441, in execute
output = self.handle(*args, **options)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\core\management\command
s\migrate.py", line 221, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\db\migrations\executor.
py", line 110, in migrate
self.apply_migration(states[migration], migration, fake=fake, fake_initial=f
ake_initial)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\db\migrations\executor.
py", line 147, in apply_migration
state = migration.apply(state, schema_editor)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\db\migrations\migration
.py", line 115, in apply
operation.database_forwards(self.app_label, schema_editor, old_state, projec
t_state)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\db\migrations\operation
s\fields.py", line 62, in database_forwards
field,
File "C:\Users\noname\nowe\venv\lib\site-packages\django\db\backends\sqlite3\sch
ema.py", line 176, in add_field
self._remake_table(model, create_fields=[field])
File "C:\Users\noname\nowe\venv\lib\site-packages\django\db\backends\sqlite3\sch
ema.py", line 74, in _remake_table
self.effective_default(field)
File "C:\Users\noname\nowe\venv\lib\site-packages\django\db\backends\base\schema
.py", line 194, in effective_default
default = field.get_default()
File "C:\Users\noname\nowe\venv\lib\site-packages\django\db\models\fields\relate
d.py", line 1930, in get_default
if isinstance(field_default, self.rel.to):
TypeError: isinstance() arg 2 must be a class, type, or tuple of classes and typ
es
(venv) C:\Users\noname\nowe\budget>
我想你会得到这个错误，因为你传递一个字符串作为模型字段的第一个参数。现场调用不需要。 – nofinator
@nofinator不，这只是可选的详细名称，这是不必要的，但很好。 znawca请发布完整的追溯。 –
@DanielRoseman。糟糕，我的错误。谢谢。 – nofinator