Django - Python 3 - “AssertionError：一个模型不能有多个 AutoField。”

Posted 2023-02-24

【中文标题】Django - Python 3 - “AssertionError：一个模型不能有多个 AutoField。”

【英文标题】：Django - Python 3 - "AssertionError: A model can't have more than one AutoField."

【发布时间】：2017-09-14 06:47:49

【问题描述】：

我快疯了。

我使用 mysqlWorkbench 创建了我的数据库

This his my Schema

比我使用终端命令获取模型代码：

$python3 manage.py inspectdb

将代码传递给我的 models.py 后，我尝试在 shell 中使用模型

$python3 manage.py shell

但是我总是遇到这个错误：

“AssertionError：一个模型不能有多个 AutoField。”

但是这个错误没有意义，因为每个Model中只有一个AutoField，见：

class Brands(models.Model):
    bid = models.AutoField(db_column='BID')  # Field name made lowercase.
    name = models.CharField(db_column='Name', max_length=45, blank=True, null=True)  # Field name made lowercase.
    fair = models.IntegerField(db_column='Fair', blank=True, null=True)  # Field name made lowercase.
    eco = models.IntegerField(db_column='Eco', blank=True, null=True)  # Field name made lowercase.
    country = models.CharField(db_column='Country', max_length=45, blank=True, null=True)  # Field name made lowercase.
    companies = models.ForeignKey('Companies', models.DO_NOTHING, db_column='Companies_ID')  # Field name made lowercase.

    class Meta:
        managed = False
        db_table = 'Brands'
        unique_together = (('bid', 'companies'),)


class Companies(models.Model):
    cid = models.AutoField(db_column='CID')  # Field name made lowercase.
    name = models.CharField(db_column='Name', max_length=45, blank=True, null=True)  # Field name made lowercase.
    fair = models.IntegerField(db_column='Fair', blank=True, null=True)  # Field name made lowercase.
    eco = models.IntegerField(db_column='Eco', blank=True, null=True)  # Field name made lowercase.
    country = models.CharField(db_column='Country', max_length=45, blank=True, null=True)  # Field name made lowercase.
    concerns = models.ForeignKey('Concerns', models.DO_NOTHING, db_column='Concerns_ID')  # Field name made lowercase.

    class Meta:
        managed = False
        db_table = 'Companies'
        unique_together = (('cid', 'concerns'),)


class Concerns(models.Model):
    cid = models.AutoField(db_column='CID', primary_key=True)  # Field name made lowercase.
    name = models.CharField(db_column='Name', max_length=45, blank=True, null=True)  # Field name made lowercase.
    fair = models.IntegerField(blank=True, null=True)
    eco = models.IntegerField(db_column='Eco', blank=True, null=True)  # Field name made lowercase.
    country = models.CharField(db_column='Country', max_length=45, blank=True, null=True)  # Field name made lowercase.

    class Meta:
        managed = False
        db_table = 'Concerns'


class Products(models.Model):
    pid = models.AutoField(db_column='PID')  # Field name made lowercase.
    name = models.CharField(db_column='Name', max_length=45, blank=True, null=True)  # Field name made lowercase.
    ean = models.IntegerField(db_column='EAN', blank=True, null=True)  # Field name made lowercase.
    fair = models.IntegerField(db_column='Fair', blank=True, null=True)  # Field name made lowercase.
    eco = models.IntegerField(db_column='Eco', blank=True, null=True)  # Field name made lowercase.
    companies_id = models.IntegerField(db_column='Companies_ID')  # Field name made lowercase.
    brands = models.ForeignKey(Brands, models.DO_NOTHING, db_column='Brands_ID')  # Field name made lowercase.
    brands_companies = models.ForeignKey(Brands, models.DO_NOTHING, db_column='Brands_Companies_ID')  # Field name made lowercase.

    class Meta:
        managed = False
        db_table = 'Products'
        unique_together = (('pid', 'companies_id', 'brands', 'brands_companies'),)


class ProductsHasShoppinglists(models.Model):
    products = models.ForeignKey(Products, models.DO_NOTHING, db_column='Products_ID')  # Field name made lowercase.
    products_companies = models.ForeignKey(Products, models.DO_NOTHING, db_column='Products_Companies_ID')  # Field name made lowercase.
    shoppinglists = models.ForeignKey('Shoppinglists', models.DO_NOTHING, db_column='ShoppingLists_ID')  # Field name made lowercase.
    shoppinglists_users = models.ForeignKey('Shoppinglists', models.DO_NOTHING, db_column='ShoppingLists_Users_ID')  # Field name made lowercase.

    class Meta:
        managed = False
        db_table = 'Products_has_ShoppingLists'
        unique_together = (('products', 'products_companies', 'shoppinglists', 'shoppinglists_users'),)


class Shoppinglists(models.Model):
    id = models.AutoField(db_column='ID')  # Field name made lowercase.
    products = models.CharField(db_column='Products', max_length=45, blank=True, null=True)  # Field name made lowercase.
    users = models.ForeignKey('Users', models.DO_NOTHING, db_column='Users_ID')  # Field name made lowercase.

    class Meta:
        managed = False
        db_table = 'ShoppingLists'
        unique_together = (('id', 'users'),)


class Users(models.Model):
    uid = models.AutoField(db_column='UID', primary_key=True)  # Field name made lowercase.
    firstname = models.CharField(db_column='FirstName', max_length=45, blank=True, null=True)  # Field name made lowercase.
    lastname = models.CharField(db_column='LastName', max_length=45, blank=True, null=True)  # Field name made lowercase.
    email = models.CharField(db_column='Email', max_length=45, blank=True, null=True)  # Field name made lowercase.

    class Meta:
        managed = False
        db_table = 'Users'

我就是不明白这个问题！！！

【参考方案1】：

来自docs：

默认情况下，Django 为每个模型提供以下字段：

id = models.AutoField(primary_key=True)

这是一个自动递增的主键。

如果您想指定自定义主键，只需指定 primary_key=True 在您的一个字段上。如果 Django 看到你 显式设置 Field.primary_key，它不会添加自动 id 列。

每个模型只需要一个字段来使 primary_key=True（要么 显式声明或自动添加）。

所以尝试像这样设置primary_key=True：

bid = models.AutoField(db_column='BID', primary_key=True)

【讨论】：

我的问题是我没有意识到自动添加的列也是一个AutoField。感谢您的报价以及提示和提示等！ ?

【参考方案2】：

尝试在您的 AutoField 中设置 primary_key=True。因为如果您不设置 primary_key=True django 将自动创建其他 AutoFiled。请参阅下面的文档：

https://docs.djangoproject.com/en/1.11/ref/models/fields/ https://docs.djangoproject.com/en/1.11/topics/db/models/#automatic-primary-key-fields