Django为什么在应用迁移时创建一个字段？

有一些模型，为什么在python manage.py makemigrations仅由迁移中的1个字段创建之后，如何修复它？我尝试过执行manage.py migrate——伪零，然后再次执行迁移，但什么都没有。该应用程序已在“设置”中注册。

---

字段不应以逗号（

，

）结尾。如果您添加一个尾随逗号，它会将字段包装在一个单元组中，因此Django无法检测该字段：

from django.db import models
from django.urls import reverse

class Category(models.Model):
   image = models.ImageField(default='default.png', upload_to='category_image')
   title = models.CharField(max_length=50, db_index = True)

   def __str__(self):
        return self.title

   def get_absolute_url(self):
        return reverse('category_detail_url', kwargs={'title': self.title})


class Provider(models.Model):
    name = models.CharField(max_length=50, db_index=True)
    phone_number = models.CharField(max_length=12, db_index=True)
    address = models.CharField(max_length=50, db_index=True)

    def __str__(self):
        return self.name


class Product(models.Model):
    title = models.CharField(max_length=50, db_index = True)
    receipt_date = models.DateTimeField(auto_now_add=True, blank=True)
    quantity_stock = models.IntegerField()
    quantity_store = models.IntegerField()
    purchase_price = models.IntegerField()
    image = models.ImageField(default='default.png', upload_to='product_image')
    provider = models.ForeignKey(
        Provider,
        null=True,
        related_name='products',
        on_delete=models.CASCADE
    )
    category =  models.ForeignKey(
        Category,
        null=True,
        related_name='products',
        on_delete=models.CASCADE
    )

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse('product_detail_url', kwargs={'title': self.title})


class Sale(models.Model):

    product = models.ForeignKey(
        Product,
        related_name='sales',
        on_delete=models.CASCADE
    )
    date_of_sale = models.DateTimeField(auto_now_add=True, blank=True)
    quantity_goods_sold = models.IntegerField()
    retail_price = models.IntegerField()

    def __str__(self):
        return self.id

---

因为您在字段中添加了尾随逗号，因此将字段包装在一个元组中。请删除末尾的逗号，以便

IntegerField（）

而不是

IntegerField（），

。

from django.db import models
from django.urls import reverse

class Category(models.Model):
   image = models.ImageField(default='default.png', upload_to='category_image')
   title = models.CharField(max_length=50, db_index = True)

   def __str__(self):
        return self.title

   def get_absolute_url(self):
        return reverse('category_detail_url', kwargs={'title': self.title})


class Provider(models.Model):
    name = models.CharField(max_length=50, db_index=True)
    phone_number = models.CharField(max_length=12, db_index=True)
    address = models.CharField(max_length=50, db_index=True)

    def __str__(self):
        return self.name


class Product(models.Model):
    title = models.CharField(max_length=50, db_index = True)
    receipt_date = models.DateTimeField(auto_now_add=True, blank=True)
    quantity_stock = models.IntegerField()
    quantity_store = models.IntegerField()
    purchase_price = models.IntegerField()
    image = models.ImageField(default='default.png', upload_to='product_image')
    provider = models.ForeignKey(
        Provider,
        null=True,
        related_name='products',
        on_delete=models.CASCADE
    )
    category =  models.ForeignKey(
        Category,
        null=True,
        related_name='products',
        on_delete=models.CASCADE
    )

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse('product_detail_url', kwargs={'title': self.title})


class Sale(models.Model):

    product = models.ForeignKey(
        Product,
        related_name='sales',
        on_delete=models.CASCADE
    )
    date_of_sale = models.DateTimeField(auto_now_add=True, blank=True)
    quantity_goods_sold = models.IntegerField()
    retail_price = models.IntegerField()

    def __str__(self):
        return self.id