How to delete all data for one and only one app in Django

Question

I have a set up (Django 1.11) with several apps including OOK, EEK, and others irrelevant ones. I want to delete all the data for OOK while leaving EEK (and the rest) untouched. Ideally, I want all the primary keys to be reset as well so the first new OOK model will get 1 and so on…

Is this possible?

All I can find is reset and sqlclear which are both deprecated. flush removed all data from the database and thus not what I want

I do release that this is an odd thing to do, but this is the hand given to me…

As far as I know, handing out `id`s, is something that happens at the database layer, hence Django has not much to say on that. You can do this with raw queries, but that is probably not a good idea. — Willem Van Onsem, May 10 '18 at 08:02
The easiest way is using `python manage.py flush` you could read the documentation https://docs.djangoproject.com/en/1.11/ref/django-admin/#flush — Panos Angelopoulos, May 10 '18 at 08:02
@WillemVanOnsem I get that but those are the requirements I have to work under. I am happy to mess with raw SQL and clearly will test this before doing it on the main database which will be backed up. — Sardathrion - against SE abuse, May 10 '18 at 08:07
@Sardathrion my mistake I didn't read it correctly. So in my ears, it sounds like non-possible but I will be waiting for an answer by someone more relevant in this field. — Panos Angelopoulos, May 10 '18 at 08:09
@Sardathrion: well for MySQL you can reset the index with https://stackoverflow.com/a/8923132/67579 — Willem Van Onsem, May 10 '18 at 08:09

Alberto · Answer 1 · 2023-03-06T07:41:07.410

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You can achieve this behaviour dropping all the tables of that <app> and then migrating only that <app>. That way you'll reset the tables of the <app>. In django 1.7+ you can do:

$ python manage.py migrate OOK zero //This command unapply your migrations
$ python manage.py migrate OOK

https://docs.djangoproject.com/en/2.0/ref/django-admin/#django-admin-migrate

edited Mar 06 '23 at 07:41

answered May 10 '18 at 08:50

Alberto

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Would you not lose all data for OOK by doing this? Unless you have migrations for data as well... – Laurent S May 10 '18 at 09:34
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Yes, but that's what he asked for "...I want to delete all the data for OOK...". Didn't he? – Alberto May 10 '18 at 10:26
It's dangerous, because it can lead to unapplying migrations in other apps! – Mark Mishyn Apr 07 '21 at 08:50
Also unfortunately it does not work if your data migrations don't have reverse functions. But it's not a big deal to add dummy reverse lambda-functions to data migrations. – Mark Mishyn Apr 07 '21 at 08:54

score 1 · Answer 2 · answered May 10 '18 at 08:41

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If you are allowed to replace the db, you could export the data you need to a fixture, then do some clever text processing in the json that is in there, say by finding all ID fields and replacing them from 1. Then reimport the result into a clean db?

The ids are autoincremented by postgresql, according to this answer you can reset the index sequence, but not even sure it can go back to 1.

But really what's the point of resetting the indexes?

answered May 10 '18 at 08:41

Laurent S

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Some of the indexes are used as serial numbers for items. Manager wanted them back to 1 or 1000 whatever was easiest. – Sardathrion - against SE abuse May 10 '18 at 08:48

score 1 · Answer 3 · answered May 10 '18 at 08:46

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This might not be possible with django. However, it is doable with raw SQL:

SET FOREIGN_KEY_CHECKS = 0;

TRUNCATE OOK_table1;
TRUNCATE OOK_table2;
[…]

SET FOREIGN_KEY_CHECKS = 1;

⚠ Do take a backup of your database before doing that!

answered May 10 '18 at 08:46

Sardathrion - against SE abuse

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How to delete all data for one and only one app in Django

3 Answers3