Django provides a working default logging configuration that is readily extended.
To send a log message from within your code, you place a logging call into it.
Don't be tempted to use logging calls in settings.py.
The way that Django logging is configured as part of the setup()
function means that logging calls placed in settings.py may not work as
expected, because logging will not be set up at that point. To explore
logging, use a view function as suggested in the example below.
First, import the Python logging library, and then obtain a logger instance
with logging.getLogger(). Provide the getLogger() method with a
name to identify it and the records it emits. A good option is to use
__name__ (see 使用命名空间日志记录器 below for more on this) which will
provide the name of the current Python module as a dotted path:
import logging
logger = logging.getLogger(__name__)
It's a good convention to perform this declaration at module level.
And then in a function, for example in a view, send a record to the logger:
def some_view(request):
...
if some_risky_state:
logger.warning("Platform is running at risk")
When this code is executed, a LogRecord containing that
message will be sent to the logger. If you're using Django's default logging
configuration, the message will appear in the console.
The WARNING level used in the example above is one of several
logging severity levels: DEBUG,
INFO, WARNING, ERROR, CRITICAL. So, another example might be:
logger.critical("Payment system is not responding")
重要
Records with a level lower than WARNING will not appear in the console
by default. Changing this behavior requires additional configuration.
Although Django's logging configuration works out of the box, you can control exactly how your logs are sent to various destinations - to log files, external services, email and so on - with some additional configuration.
你可以配置：
LogRecord objects to a string or
other form for consumption by human beings or another systemThere are various ways of configuring logging. In Django, the
LOGGING setting is most commonly used. The setting uses the
dictConfig format, and extends the
default logging configuration.
See 日志模块的配置 for an explanation of how your custom settings are merged with Django's defaults.
See the Python logging documentation for
details of other ways of configuring logging. For the sake of simplicity, this
documentation will only consider configuration via the LOGGING setting.
When configuring logging, it makes sense to
LOGGING 目录¶在你的 settings.py:: 中
LOGGING = {
"version": 1, # the dictConfig format version
"disable_existing_loggers": False, # retain the default loggers
}
It nearly always makes sense to retain and extend the default logging
configuration by setting disable_existing_loggers to False.
This example configures a single handler named file, that uses Python's
FileHandler to save logs of level DEBUG and higher to the
file general.log (at the project root):
LOGGING = {
# ...
"handlers": {
"file": {
"class": "logging.FileHandler",
"filename": "general.log",
},
},
}
Different handler classes take different configuration options. For more
information on available handler classes, see the
AdminEmailHandler provided by Django and the various
handler classes provided by Python.
Logging levels can also be set on the handlers (by default, they accept log messages of all levels). Using the example above, adding:
{
"class": "logging.FileHandler",
"filename": "general.log",
"level": "DEBUG",
}
would define a handler configuration that only accepts records of level
DEBUG and higher.
To send records to this handler, configure a logger mapping to use it for example:
LOGGING = {
# ...
"loggers": {
"": {
"level": "DEBUG",
"handlers": ["file"],
},
},
}
The mapping's name determines which log records it will process. This
configuration ('') is unnamed. That means that it will process records
from all loggers (see 使用命名空间日志记录器 below on how to use the mapping
name to determine the loggers for which it will process records).
It will forward messages of levels DEBUG and higher to the handler named
file.
Note that a logger can forward messages to multiple handlers, so the relation between loggers and handlers is many-to-many.
If you execute:
logger.debug("Attempting to connect to API")
in your code, you will find that message in the file general.log in the
root of the project.
By default, the final log output contains the message part of each log
record. Use a formatter if you want to include additional
data. First name and define your formatters - this example defines
formatters named verbose and simple:
LOGGING = {
# ...
"formatters": {
"verbose": {
"format": "{name} {levelname} {asctime} {module} {process:d} {thread:d} {message}",
"style": "{",
},
"simple": {
"format": "{levelname} {message}",
"style": "{",
},
},
}
The style keyword allows you to specify { for str.format() or
$ for string.Template formatting; the default is $.
See LogRecord attributes for the LogRecord attributes
you can include.
To apply a formatter to a handler, add a formatter entry to the handler's
dictionary referring to the formatter by name, for example:
"handlers": {
"file": {
"class": "logging.FileHandler",
"filename": "general.log",
"formatter": "verbose",
},
}
The unnamed logging configuration '' captures logs from any Python
application. A named logging configuration will capture logs only from loggers
with matching names.
The namespace of a logger instance is defined using
getLogger(). For example in views.py of my_app:
logger = logging.getLogger(__name__)
will create a logger in the my_app.views namespace. __name__ allows you
to organize log messages according to their provenance within your project's
applications automatically. It also ensures that you will not experience name
collisions.
A logger mapping named my_app.views will capture records from this logger:
LOGGING = {
# ...
"loggers": {
"my_app.views": {...},
},
}
A logger mapping named my_app will be more permissive, capturing records
from loggers anywhere within the my_app namespace (including
my_app.views, my_app.utils, and so on):
LOGGING = {
# ...
"loggers": {
"my_app": {...},
},
}
You can also define logger namespacing explicitly:
logger = logging.getLogger("project.payment")
and set up logger mappings accordingly.
Logger naming is hierarchical. my_app is the parent of my_app.views,
which is the parent of my_app.views.private. Unless specified otherwise,
logger mappings will propagate the records they process to their parents - a
record from a logger in the my_app.views.private namespace will be handled
by a mapping for both my_app and my_app.views.
To manage this behavior, set the propagation key on the mappings you define:
LOGGING = {
# ...
"loggers": {
"my_app": {
# ...
},
"my_app.views": {
# ...
},
"my_app.views.private": {
# ...
"propagate": False,
},
},
}
propagate defaults to True. In this example, the logs from
my_app.views.private will not be handled by the parent, but logs from
my_app.views will.
当日志包含尽可能多的信息，而不是您不需要的信息时，日志是最有用的——需要多少取决于您正在做的事情。在调试时，您需要一定程度的信息，如果您不得不在生产环境中处理这些信息，那么这些信息将是多余的，而且毫无用处。
You can configure logging to provide you with the level of detail you need, when you need it. Rather than manually change configuration to achieve this, a better way is to apply configuration automatically according to the environment.
For example, you could set an environment variable DJANGO_LOG_LEVEL
appropriately in your development and staging environments, and make use of it
in a logger mapping thus:
"level": os.getenv("DJANGO_LOG_LEVEL", "WARNING")
- so that unless the environment specifies a lower log level, this
configuration will only forward records of severity WARNING and above to
its handler.
Other options in the configuration (such as the level or formatter
option of handlers) can be similarly managed.
5月 31, 2023