CODEWITHSUNDEEP
pythondjangodatabase-migrationdjango-apps
guettli
guettli

Reputation: 27189

How to remove an app from a django projects (and all its tables)

I want to remove an app from a django project.

I want to remove

Running manage.py migrate app_to_remove zero does not work:

django.db.migrations.migration.IrreversibleError: 
Operation <RunPython <function forwards_func at 0x7ff76075d668>> in
            fooapp.0007_add_bar is not reversible

I guess there are several migrations which are not reversible ...

Upvotes: 13

Views: 14962

Answers (3)

Markus Amalthea Magnuson
Markus Amalthea Magnuson

Reputation: 8761

This is what the official documentation suggests for the latest version as of now, which is 4.2:

  1. Remove all references to the app (imports, foreign keys etc.).
  2. Remove all models from the corresponding models.py file.
  3. Create relevant migrations by running makemigrations. This step generates a migration that deletes tables for the removed models, and any other required migration for updating relationships connected to those models.
  4. Squash out references to the app in other apps’ migrations.
  5. Apply migrations locally, runs tests, and verify the correctness of your project.
  6. Deploy/release your updated Django project.
  7. Remove the app from INSTALLED_APPS.
  8. Finally, remove the app’s directory.

Upvotes: 2

guettli
guettli

Reputation: 27189

First: Remove references in the code

  • remove app_to_remove from settings.INSTALLED_APPS
  • remove other references in urls.py or other places

Second: Clean the database

Create an empty migration for your django-project:

manage.py makemigrations your_django_project --empty

Edit the file. Here is a template:

# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import migrations, models


class Migration(migrations.Migration):

    dependencies = [
        ('your_django_project', '0001_initial'),
    ]

    operations = [
        migrations.RunSQL('''
        drop table if exists app_to_remove_table1;
        drop table if exists app_to_remove_table2;
        ....
        delete from auth_permission where content_type_id in (select id from django_content_type where app_label = '{app_label}');
        delete from django_admin_log where content_type_id in (select id from django_content_type where app_label = '{app_label}');
        delete from django_content_type where app_label = '{app_label}';
        delete from django_migrations where app='{app_label}';
        '''.format(app_label='app_to_remove'))
    ]

Run the migration, run tests.

About "drop if exists": You have two cases:

  1. The production system: You want to drop the tables.
  2. New development systems: These systems never had this app, and they don't have this table :-)

Upvotes: 23

L&#234; Vũ L&#226;m
L&#234; Vũ L&#226;m

Reputation: 337

Note: this guide is successful with Django 3.1.1 and Python 3.8.2

Can you try this solution to clean your database and migrations first

Step 1: Delete your table from the file your_app/models.py but leave the file itself

Step 2: Check your register in the file admin.py if you have

Step 3: create migration:

manage.py makemigrations your_app

Step 4: migrate into database:

manage.py migrate

you can see the result in my example enter image description here

Step 5: delete all the files in the folder your_app/migrations

Step 6: Remove migrations in the table django_migrations

python manage.py migrate --fake your_app zero

Check migrations:

python manage.py showmigrations

Step 7: Then you can remove the app completely,check reference,INSTALLED_APPS

Upvotes: 1

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