Log SQL queries even if DEBUG=False - django

Question

This is my logging config in settings.py
LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'handlers': {
'console': {
'class': 'logging.StreamHandler',
},
'file': {
'class': 'logging.FileHandler',
'filename': os.path.join(BASE_DIR, 'logs', 'django.log'),
},
},
'loggers': {
'django': {
'handlers': ['file', 'console'],
'level': 'DEBUG',
},
'django.template': {
'handlers': ['file', 'console'],
'level': 'INFO',
},
'App': {
'handlers': ['file', 'console'],
'level': 'DEBUG',
},
},
}
There's a behavior that I can't explain: if I run with debug=True I can see all SQL queries being logged to the console, but when debug=False that doesn't happen, even if I don't change the configuration above.
Why is this? How can I determine in my logging config whether or not SQL queries are logged to the console?

Answer 1

Query logging goes way deeper as Django wraps the database cursor based on the truthiness of a computed property.
From Line 226, django.db.backends.base.base v2.2.6 sources
def _prepare_cursor(self, cursor):
"""
Validate the connection is usable and perform database cursor wrapping.
"""
self.validate_thread_sharing()
if self.queries_logged:
wrapped_cursor = self.make_debug_cursor(cursor)
else:
wrapped_cursor = self.make_cursor(cursor)
return wrapped_cursor
This computed property gets to be decided on where debugging is forced or debugging is enabled in project settings
From Line 149, django.db.backends.base.base v2.2.6 sources
#property
def queries_logged(self):
return self.force_debug_cursor or settings.DEBUG
You should be able to get a proxy to the default connection and force the debug cursor to be used.
from django.db import connection
connection.force_debug_cursor = True
I however advise against this approach and favor query audits in the database.

Answer 2

That's because existing loggers already filtered your logs. In this case is Django's logger.
DEFAULT_LOGGING = {
'filters': {
'require_debug_true': {
'()': 'django.utils.log.RequireDebugTrue',
},
},
'handlers': {
'console': {
'level': 'INFO',
'filters': ['require_debug_true'],
'class': 'logging.StreamHandler',
},
...
}
and django.utils.log.RequireDebugTrue
class RequireDebugTrue(logging.Filter):
def filter(self, record):
return settings.DEBUG
To solve this issue, you could disable existing loggers by set disable_existing_loggers: True or you can override the filter like so:
LOGGING = {
...
'handlers': {
'console': {
'class': 'logging.StreamHandler',
'filters': [],
},
...
}

Answer 3

Step 1: Write patch_django function in patchers.py
# Created by BaiJiFeiLong#gmail.com at 2022/6/6
import importlib
import importlib.util
import sys
# noinspection DuplicatedCode
def patch_module(module_name, modification_func):
spec = importlib.util.find_spec(module_name)
source = spec.loader.get_source(module_name)
source = modification_func(source)
module = importlib.util.module_from_spec(spec)
code = compile(source, module.__spec__.origin, 'exec')
exec(code, module.__dict__)
sys.modules[module_name] = module
return module
def patch_django():
patch_module("django.db.backends.base.base", lambda x: x.replace(
"self.force_debug_cursor = False",
"self.force_debug_cursor = True"))
Step2: Call patch_django before django imported.
manage.py
__import__("importlib").import_module("patchers").patch_django() # noqa
import os
import sys
def main():
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'mysite.settings')
try:
from django.core.management import execute_from_command_line
except ImportError as exc:
raise ImportError(
"Couldn't import Django. Are you sure it's installed and "
"available on your PYTHONPATH environment variable? Did you "
"forget to activate a virtual environment?"
) from exc
execute_from_command_line(sys.argv)
if __name__ == '__main__':
main()
wsgi.py
__import__("importlib").import_module("patchers").patch_django() # noqa
import os
from django.core.wsgi import get_wsgi_application
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'mysite.settings')
application = get_wsgi_application()
asgi.py
__import__("importlib").import_module("patchers").patch_django() # noqa
import os
from django.core.asgi import get_asgi_application
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'mysite.settings')
application = get_asgi_application()
Step 3: Make sure django.db.backends is in debug level
'django.db.backends': {
'level': 'DEBUG',
},