flake8-django-migrations

Flake8 plugin to lint for backwards incompatible database migrations.

Installation

Install using pip (or your favourite package manager):

pip install flake8-django-migrations

Usage

This plugin should be used automatically when running flake8:

flake8

Checks

This is the list of checks currently implemented by this plugin.

DM001

RemoveField operation should be wrapped in SeparateDatabaseAndState.

Such an operation should be run in two separate steps, using SeparateDatabaseAndState, otherwise it is not backwards compatible.

• Step 1: remove the field from the model and code. For foreign key fields, the foreign key constraint should also be dropped.
• Step 2: remove the column from the database.

Bad

class Migration(migrations.Migration):
    operations = [
        migrations.RemoveField(
            model_name="order",
            name="total",
        ),
    ]

Good

class Migration(migrations.Migration):
    operations = [
        migrations.SeparateDatabaseAndState(
            state_operations=[
                migrations.RemoveField(
                    model_name="order",
                    name="total",
                ),
            ],
        ),
    ]