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I wrote a simple script for populating the table created with Django models. I did make mistakes during the development process and have corrupted data in my table (it is accessible but has wrong images, names, urls). I want to erase this data and start the populating over, but it looks like the table stores previous primary keys (so the new objects do not start from pk=1) if I just use Model.objects.all().delete().

How can I erase all the previous data without DROP TABLE? If DROP is the most convenient way, is this Django : Table doesn't exist solution for restoring is the only one?

The desired functionality is erasing data before every script run, automatically. Thank you in advance.

Georgy
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  • Are you using SQLite? – doru Dec 04 '15 at 08:25
  • What do you mean by "before every script run"? – Sayse Dec 04 '15 at 08:27
  • @doru I have different DB management systems on different machines (develop using both of them: home and work), sqlite and mysql. Isn't django orm database-agnostic in this case? – Georgy Dec 04 '15 at 08:29
  • @Sayse 1. Erase previous data with Django ORM, the table is absolutely new and clean. 2. Start populating. Everything from the same script. – Georgy Dec 04 '15 at 08:32
  • Do you mean you have a script you run? you can just add flush to the beginning of that – Sayse Dec 04 '15 at 08:33
  • @Georgy Yes, it is. But if you only need to drop a SQLite db, you only have to delete the db file inside your proejct and then run `makemigrations` and `migrate` again to have a new database. – doru Dec 04 '15 at 08:41
  • @Sayse very close to it. I'll google how to add it into script, thank you. Are there any ways to use flush just for the set of tables, not database? – Georgy Dec 04 '15 at 08:41
  • Not really, you can specify what database you want to flush but you can't specify tables for good reason, it stops you from invalidating database entries – Sayse Dec 04 '15 at 08:43
  • @Sayse alright then. Would you please add this information (the last comment about tables) to your answer, just to make it complete (I haven't enough rating to add my comments, sorry). I'll mark it as the answer. Thanks a lot for your help! – Georgy Dec 04 '15 at 08:49
  • @Georgy - Done, enjoy! – Sayse Dec 04 '15 at 08:51
  • @doru Thank you, this is a way to drop the db with fewer iterations of `migrate`, though the using of `flush` looks a bit more convenient. Your solution helps me to understand the project structure anyway. Thank you for your help. – Georgy Dec 04 '15 at 08:52

3 Answers3

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You can just use flush

Removes all data from the database and re-executes any post-synchronization handlers. The table of which migrations have been applied is not cleared.

Called via manage.py flush

Are there any ways to use flush just for the set of tables, not database?

No, not really. Flush has an option to specify what database you're flushing (-database) but you can't specify certain tables since that has the possibility of breaking relationships between tables which would invalidate data.

If you really need to do this, you could of course make your own command that will just go through the tables and delete the objects but this of course won't do the post-synchronization steps that flush does

Sayse
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  • A little hack, if you use this command a lot then you can type in `python manage.py flush --noinput` - no need to type in `yes` all the time. – Georgy Dec 23 '15 at 08:31
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There is a way to drop only the tables of a given django app and not the whole database: you can use sqlclear and pipe it to dbshell management command.

python manage.py sqlclear app_name | python manage.py dbshell

The command can be applied only if the app has no migrations. See here more info.

doru
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I also needed a way to clear particular tables before using loaddata to backport data to test environments. This works for a particular table:

echo "delete from my_table" | python manage.py dbshell
Aaron Williams
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