Question

我的模特

class BaseModel(models.Model):
    CreatedDate = models.DateTimeField(auto_now_add=True, verbose_name="Oluşturulma Tarihi")
    ModifiedDate = models.DateTimeField(auto_now=True, verbose_name="Son Güncellenme tarihi")
    Isdeleted = models.BooleanField(verbose_name="Silindi", default=False)

class Case(BaseModel):
    CaseNumber = models.CharField(max_length=14)
    Customer = models.ForeignKey(Customer)
    Title = models.ForeignKey(CaseTitle)
    CaseCategory = models.ForeignKey(CaseCategory, verbose_name="Kategori")
    Priority = models.ForeignKey(CasePriority)
    Status = models.ForeignKey(CaseStatus)
    Detail = models.TextField()
    Group = models.ForeignKey(Group)
    User = models.ForeignKey(User,related_name='User' )
    AssignedUser = models.ForeignKey(User,related_name='AssignedUser')
    CloseDetail = models.TextField blank=True)

我只是想给我的模型提供2个外键，但错误是

Traceback (most recent call last):   
File "/usr/local/lib/python3.6/site-packages/django/db/models/fields/related.py", line 796, in __init__
    to._meta.model_name AttributeError: 'ForeignKey' object has no attribute '_meta'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):   
File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)   
File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
    utility.execute()   
File "/usr/local/lib/python3.6/site-packages/django/core/management/__init__.py", line 338, in execute
    django.setup()   
File "/usr/local/lib/python3.6/site-packages/django/__init__.py", line 27, in setup
    apps.populate(settings.INSTALLED_APPS)   
File "/usr/local/lib/python3.6/site-packages/django/apps/registry.py", line 108, in populate
    app_config.import_models()   
File "/usr/local/lib/python3.6/site-packages/django/apps/config.py", line 202, in import_models
    self.models_module = import_module(models_module_name)   
File "/usr/local/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 "/code/Case/models.py", line 91, in <module>
    class Case(BaseModel):   
File "/code/Case/models.py", line 101, in Case
    AssignedUser = models.ForeignKey(User,related_name='AssignedUser')   
File "/usr/local/lib/python3.6/site-packages/django/db/models/fields/related.py", line 802, in __init__
    RECURSIVE_RELATIONSHIP_CONSTANT, AssertionError: ForeignKey(<django.db.models.fields.related.ForeignKey>) is invalid.
First parameter to ForeignKey must be either a model, a model name, or the string 'self'

Answer 1

将字段名称User更改为您想要的任何内容。这与您收到错误的原因相冲突。

class MultiCoupon {
    public static function getChildCouponByMainCouponCode($main_coupon_code, $provider_condition) {
        global $sql_tbl;

        $child_discount_coupon_data = func_query_first("SELECT child_coupons.* FROM $sql_tbl[discount_coupons] as child_coupons INNER JOIN $sql_tbl[discount_coupons_links] as main_coupons ON child_coupons.main_code = main_coupons.code AND main_coupons.code='" . addslashes($main_coupon_code) . "' $provider_condition");
        return $child_discount_coupon_data;
    }
}

Answer 2

如果只与模型User实现一个关系，它是否有效？错误消息：

First parameter to ForeignKey must be either a model, a model name, or the string 'self'

让我假设您没有传递User模型的实际类。你是如何获得它的？

另外，通过查看我认为BaseModel的字段，它可能是一个抽象的基本模型：

class BaseModel(models.Model):
    class Meta:
        abstract = True

    CreatedDate = models.DateTimeField(auto_now_add=True, verbose_name="Oluşturulma Tarihi")
    ...

有关详细信息，请参阅此处：https://godjango.com/blog/django-abstract-base-class-model-inheritance/

Answer 3

您正在重新定义User Django代码的相关部分是isinstance(to, str)，这意味着User不是模型，但它也不是一个字符串（＆＃39; sa ForeignKey）。

如果您正在使用Django的用户模型或自定义变体，那么单独获取参考的正确方法是使用django.contrib.auth.get_user_model()。 e.g：

from django.contrib.auth import get_user_model
User = get_user_model()

class MyModel(models.Model):
    user = models.ForeignKey(User)

在Python中，它的约定是小写名称，除非它们是类。

Answer 4

你应该遵循python约定关于如何使用大写，小写，否则解释器将引用错误的变量：

类是唯一应该是驼峰式的事物（class User，class CaseTitle）。
您的类属性（实例变量）应为小写，并带有下划线：case_number, user, assigned_user, etc...

当您撰写User = ForeignKey(User)时，您实际上正在重新定义User变量，因此在下一行AssignedUser = ForeignKey(User)中，User不是User模型上课了。如果我把它写出来，我会得到：

AssignedUser = models.ForeignKey( # User
    models.ForeignKey(  # User
        models.ForeignKey(  # User etc...
            ...

django同一型号的两个外键

4 个答案: