Executing Django's sqlsequencereset code from within python

Question

Django's sqlsequencereset command returns the SQL commands needed to reset sequences in the database.

Other similar management commands automatically execute the SQL by default (and only print out the output if you specify the --dry-run option).

From the command line you can execute the returned commands with:

python manage.py sqlsequencereset app1_name app2_name | python manage.py dbshell

But... Is there a way to directly execute the returned code from sqlsequencereset from inside python?

Answer 1

You can execute the SQL query generated by sqlsequencereset from within python in this way (using the default database):

from django.core.management.color import no_style
from django.db import connection

from myapps.models import MyModel1, MyModel2


sequence_sql = connection.ops.sequence_reset_sql(no_style(), [MyModel1, MyModel2])
with connection.cursor() as cursor:
    for sql in sequence_sql:
        cursor.execute(sql)

I tested this code with Python3.6, Django 2.0 and PostgreSQL 10.

Answer 2

I'm currently managing this by:

1. Using call_command to run sqlsequencereset
2. Grabbing the output into an in-memory StringIO object (instead of writing to a file on disc)
3. Executing the SQL directly against Django's default database

Code:

import io

from django.core.management import call_command
from django.db import connection


app_name = 'my_app'

# Get SQL commands from sqlsequencereset
output = io.StringIO()
call_command('sqlsequencereset', app_name, stdout=output, no_color=True)
sql = output.getvalue()
    
with connection.cursor() as cursor:
    cursor.execute(sql)

output.close()