问题
I am trying to log sql statements in a code in my Django Application
Currently i am using the following logger config in my settings.py
LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'formatters': {
'sql': {
'()': SQLFormatter,
'format': '[%(duration).3f] %(statement)s',
},
'verbose': {
'format': '%(levelname)s %(funcName)s() %(pathname)s[:%(lineno)s] %(name)s \n%(message)s'
}
},
'handlers': {
'console': {
'level': 'DEBUG',
'formatter': 'verbose',
'class': 'logging.StreamHandler',
},
'sql': {
'class': 'logging.StreamHandler',
'formatter': 'sql',
'level': 'DEBUG',
}
}
}
In genereal to log sql in django we can add the django.db.backends to the logger.config in the settings.py
'loggers': {
'django.db.backends': {
'handlers': ['sql'],
'level': 'DEBUG',
'propagate': False,
},
But the problem is it will log every sql statement. So how can we start and stop logging for django.db.backends in between code.
I have the following code in my views.py
def someview(request)
# start logging from here
user_set = User.objects.all()
for user in user_set:
print(user.last_name)
# stop logging from here
Also I want to use the sql handler which I defined in the logging config.
What code will go in start and stop logging place in the above view function.
回答1:
Create a filter class and add an instance to the logger or handler.
class LoggerGate:
def __init__(self, state='open'):
self.state = state
def open(self):
self.state = 'open'
def close(self):
self.state = 'closed'
def filter(self, record):
return self.state == 'open'
Create a filter, initialized in the 'closed' state. Get the 'django.db.backends' logger and add the filter.
gate = LoggerGate('closed')
sql_logger = logging.getLogger('django.db.backends')
sql_logger.addFilter(gate)
Then call the open or close method to limit logging to where you want it.
def someview(request)
gate.open() # start logging from here
user_set = User.objects.all()
for user in user_set:
print(user.last_name)
gate.close() # stop logging here
回答2:
Just summarizing from the above answer and also from the answer of Gabriel C, which both are same and also from the answer of Sraw
My goal was to log sql using django django.db.backends. But the problem with it is that it will log all the sqls. I want to log only sqls in a particular section of a code or whereever i want to see the sqls. So the following way i could do it.
logging config inside settings.py:
# Filter class to stop or start logging for "django.db.backends"
class LoggerGate:
def __init__(self, state='closed'):
# We found that the settings.py runs twice and the filters are created twice. So we have to keep only one. So we delete all the previous filters before we create the new one
import logging
logger_database = logging.getLogger("django.db.backends")
try:
for filter in logger_database.filters:
logger_database.removeFilter(filter)
except Exception as e:
pass
self.state = state
def open(self):
self.state = 'open'
def close(self):
self.state = 'closed'
def filter(self, record):
"""
Determine if the specified record is to be logged.
Is the specified record to be logged? Returns 0/False for no, nonzero/True for
yes. If deemed appropriate, the record may be modified in-place.
"""
return self.state == 'open'
LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'handlers': {
'sql': {
'class': 'logging.StreamHandler',
'level': 'DEBUG',
}
},
'filters': {
'myfilter': {
'()': LoggerGate,
}
},
'loggers': {
'django.db.backends': {
'handlers': ['sql'],
'level': 'DEBUG',
'propagate': False,
'filters': ['myfilter']
}
}
}
Then in the views.py
import logging
logger = logging.getLogger(__name__)
logger_database = logging.getLogger("django.db.backends")
def test1(request):
logger_database.filters[0].open()
#Will allow priting of sql satatements from here
from django import db
user_set = User.objects.all()
for user in user_set: # Here sql is executed and is printed to console
pass
#Will stop priting of sql satatements after this
logger_database.filters[0].close()
from django import db
user_set = User.objects.all()
for user in user_set: # Here sql is executed and is not printed to console
pass
now = datetime.datetime.now()
html = "<html><body>Internal purpose</body></html>"
return HttpResponse(html)
If one wants to print the sql in formatted and colorful way use this in the settings.py
# SQL formatter to be used for the handler used in logging "django.db.backends"
class SQLFormatter(logging.Formatter):
def format(self, record):
# Check if Pygments is available for coloring
try:
import pygments
from pygments.lexers import SqlLexer
from pygments.formatters import TerminalTrueColorFormatter
except ImportError:
pygments = None
# Check if sqlparse is available for indentation
try:
import sqlparse
except ImportError:
sqlparse = None
# Remove leading and trailing whitespaces
sql = record.sql.strip()
if sqlparse:
# Indent the SQL query
sql = sqlparse.format(sql, reindent=True)
if pygments:
# Highlight the SQL query
sql = pygments.highlight(
sql,
SqlLexer(),
#TerminalTrueColorFormatter(style='monokai')
TerminalTrueColorFormatter()
)
# Set the record's statement to the formatted query
record.statement = sql
return super(SQLFormatter, self).format(record)
# Filter class to stop or start logging for "django.db.backends"
class LoggerGate:
def __init__(self, state='closed'):
# We found that the settings.py runs twice and the filters are created twice. So we have to keep only one. So we delete all the previous filters before we create the new one
import logging
logger_database = logging.getLogger("django.db.backends")
try:
for filter in logger_database.filters:
logger_database.removeFilter(filter)
except Exception as e:
pass
self.state = state
def open(self):
self.state = 'open'
def close(self):
self.state = 'closed'
def filter(self, record):
"""
Determine if the specified record is to be logged.
Is the specified record to be logged? Returns 0/False for no, nonzero/True for
yes. If deemed appropriate, the record may be modified in-place.
"""
return self.state == 'open'
LOGGING = {
'version': 1,
'disable_existing_loggers': False,
'formatters': {
'sql': {
'()': SQLFormatter,
'format': '[%(duration).3f] %(statement)s',
}
},
'handlers': {
'sql': {
'class': 'logging.StreamHandler',
'formatter': 'sql',
'level': 'DEBUG',
}
},
'filters': {
'myfilter': {
'()': LoggerGate,
}
},
'loggers': {
'django.db.backends': {
'handlers': ['sql'],
'level': 'DEBUG',
'propagate': False,
'filters': ['myfilter']
}
}
}
来源：https://stackoverflow.com/questions/57496448/python-how-to-start-and-stop-a-logger-whenever-i-want