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Postgresql – Django: using sqlsequencereset programmatically inside a custom command

I am trying to create a custom command on Django, which will use the sqlsequencereset command for a list of app labels inside a loop, the idea is to run this command to generate and run the sequence setval query for each table of the app.

My implementation:

        for app_label in app_labels:
            output = call_command("sqlsequencereset", app_label)
            with connection.cursor() as cursor:
                cursor.execute(output)

I read inside the Django Documentation that raw queries inside cursor.execute do not support transactions, so i customized the SQL string to not include BEGIN and COMMIT keywords, but it still throws the following syntax error:

 File "/home/python/.local/lib/python3.12/site-packages/django/db/backends/utils.py", line 122, in execute
    return super().execute(sql, params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/python/.local/lib/python3.12/site-packages/django/db/backends/utils.py", line 79, in execute
    return self._execute_with_wrappers(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/python/.local/lib/python3.12/site-packages/django/db/backends/utils.py", line 92, in _execute_with_wrappers
    return executor(sql, params, many, context)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/python/.local/lib/python3.12/site-packages/django/db/backends/utils.py", line 100, in _execute
    with self.db.wrap_database_errors:
  File "/home/python/.local/lib/python3.12/site-packages/django/db/utils.py", line 91, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/python/.local/lib/python3.12/site-packages/django/db/backends/utils.py", line 103, in _execute
    return self.cursor.execute(sql)
           ^^^^^^^^^^^^^^^^^^^^^^^^
django.db.utils.ProgrammingError: syntax error at or near "
LINE 1: BEGIN;
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2

Answers


  1. Chosen as BEST ANSWER
    0

    So apparently the styling of the output text was colored, which led to the cursor not being able to process it inside the query console, I was able to get it working by using the no_color argument with the sqlsequencereset command:

        for app_label in app_labels:
        output = call_command("sqlsequencereset", app_label, no_color=True, database='default')
        with connection.cursor() as cursor:
            cursor.execute(output)

  2. 0

    The call_command(…) function [Django-doc] does not return what the command prints. The command just prints to the stdout.

    You can catch the output by storing the stdout in a StringIO we can catch the result, and thus use that in the query:

    from io import StringIO

output = StringIO()
for app_label in app_labels:
    output = call_command('sqlsequencereset', app_label, stdout=output)
    with connection.cursor() as cursor:
        cursor.execute(output.getvalue())
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