将 db_table 添加到 model 添加了 last_login 字段

Question

Background: I started a project with a custom User model. However, noob that I am, I was unaware of the AbstractBaseUser class. So I just wrote my own. The app has been deployed to prod and working fine. But now I want to switch to using AbstractBaseUser so I can take advantage of some of the built-in Django utilities (like the pre-made password resetting process). I had done this with a different app and it worked fine. But that one wasn't in prod while I made the change. Because this one is, I needed to keep the old user table while I made the changes with a copy of it. So my first step was to add db_table = test_users to my old user model, so as to keep the prod app running with an unchanged table. I ran the migration, and two unexpected things happened (I'm a noob, and that's why they were unexpected):

• The old user table was renamed. I thought a new table would be created. No problem, I quickly copied the new table and named the copy with the old table's name so the prod app could still find its users
• A column last_login was added. Why?? Here's my model, with the added db_table

    class User(models.Model):
        first_name = models.CharField(max_length=255)
        last_name = models.CharField(max_length=255)
        email = models.CharField(max_length=255)
        password = models.CharField(max_length=255)
        created_at = models.DateTimeField(auto_now_add=True)
        updated_at = models.DateTimeField(auto_now=True)
        client_id = models.IntegerField(blank=True, null=True)
        is_admin = models.BooleanField(default=False)
        is_super = models.BooleanField(default=False)
        is_active = models.BooleanField(default=True)
    
        class Meta:
            db_table = "test_users"

The big problem with this is that when I change to AbstractBaseUser and run the migration, I get an error. Looking at the migration file I see that this change creates a migration that all it tries to do is to add last_login to the table. So, of course, the error I get is "Duplicate column name 'last_login'"

So, my question is two-fold:

1. Why was that column added in the first migration?
2. If I just run migrate --fake and keep going, will it have unintended consequences? I thought this could be a good solution, given that the migration file shows nothing else is being done, and if the field already exists, then no harm done?

Answer 1

Maybe because you've changed the parent class django automatically change all the migrations that connected to your user class