在我向其中一个模型添加新字段后，无法迁移到 django 应用程序

Question

So, this was my Category model before:

class Category(models.Model):
    title = models.CharField(max_length=20)

    def __str__(self):
        return self.title

I had run makemigrations and migrate commands and the app was working just fine

Then i had to add one more field to the model:

class Category(models.Model):
    restricted = models.BooleanField(default=False)
    title = models.CharField(max_length=20)

    def __str__(self):
        return self.title

Now when i run makemigrations, it gives the following error:

return Database.Cursor.execute(self, query, params) django.db.utils.OperationalError: no such table: events_category

first it gave "no such column" error, but i don't really care about the data right now so i deleted the sqlite file and all migrations and started over, that's when this error showed up

The model has been set up as a foreign key in another model called Post:

class Post(models.Model):
    category = models.ForeignKey(Category, on_delete=models.CASCADE, default=DEFAULT_EXAM_ID)
    # and other fields...

Can someone please help me perform migrations properly after i added this field??

Answer 1

Delete the latest migrations and remigrate. The migration files are the files in the migrations folder in your specific application

still if the error exist, clear the migrations again. Now Remove the added Model. migrate without error. Then add the model again and remigrate.

Answer 2

This error pops up when you try to load data before the tables are created. You might have an import statement that attempts to load the data before migrate has been done.

Try commenting out import statement that load models and do makemigrations and migrate

Answer 3

Resolution:

1. Comment the newly added field and do fake migrations.

• python manage.py makemigrations appname
• python manaage.py migrate appname --fake

2. Uncomment the same line and do normal migrate.

• python manage.py makemigrations appname
• python manaage.py migrate appname