[PYTHON] Rename table columns in Django3

How to rename table columns in Django3

Change the pub_data of the Question model of the polls app to pub_date.

environment

• Python - 3.6.8
• Django - 3.0.2
• MySQL - 8.0.19
• CentOS7.7

manner

Create an empty migration file

Create an empty migration file on the command line by referring to the Official Document.

$ python3 manage.py makemigration --empty [app name]

Edit migration file

Then, a migration file will be created in the polls folder directly under the application.

migrations/0002_auto_20200128_0044.py

# Generated by Django 3.0.2 on 2020-01-28 00:44

from django.db import migrations


class Migration(migrations.Migration):

    dependencies = [
        ('[app name]', '0001_initial'),
    ]

    operations = [
    ]

Rewrite this as follows.

migrations/0002_auto_20200128_0044.py

# Generated by Django 3.0.2 on 2020-01-28 00:44

from django.db import migrations


class Migration(migrations.Migration):

    dependencies = [
        ('[app name]', '0001_initial'),
    ]

    operations = [
        migrations.RenameField(
            model_name='question', #Model name
            old_name='pub_data',   #Change before
            new_name='pub_date'    #After change
        )
    ]

If you rewrite the RenameField, you can add or delete columns and indexes in the same way. For more information, go to Official Documents.

Apply migration

Finally, run the following command on the command line to apply your changes.

$ python3 manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, polls, sessions
Running migrations:
  Applying polls.0002_auto_20200128_0044... OK

Let's check it on the SQL side.

mysql> DESC polls_question;
+---------------+--------------+------+-----+---------+----------------+
| Field         | Type         | Null | Key | Default | Extra          |
+---------------+--------------+------+-----+---------+----------------+
| id            | int          | NO   | PRI | NULL    | auto_increment |
| question_text | varchar(200) | NO   |     | NULL    |                |
| pub_date      | datetime(6)  | NO   |     | NULL    |                |
+---------------+--------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)

It's strange: relaxed:

Django side fix

Modify files such as model.py.

Change before

model.py

class Question(models.Model):
  question_text = models.CharField(max_length=200)
　# pub_data -> pub_date
  pub_data = models.DateTimeField('data published')

  def __str__(self):
    return self.question_text

After change

model.py

class Question(models.Model):
  question_text = models.CharField(max_length=200)
  # pub_data -> pub_date
  pub_date = models.DateTimeField('date published')

  def __str__(self):
    return self.question_text

end

Why is the function name that changes the column name RenameField instead of RenameColumn?

If anyone knows another good way, please let me know.