How to better indent multiline strings with many string formatting args?

Question

I have a function, that is used in flask, for logging application errors:

 def log_exception(self, exc_info):
 self.logger.error('''
Time: %s
Path: %s
HTTP Method: %s
POST_ARGS: %s
GET_ARGS: %s
Client IP Address: %s
User Agent: %s
User Platform: %s
User Browser: %s
User Browser Version: %s
Username: %s
Email: %s''' % (
 datetime.now(),
 request.path,
 request.method,
 request.form,
 request.args,
 request.remote_addr,
 request.user_agent.string,
 request.user_agent.platform,
 request.user_agent.browser,
 request.user_agent.version,
 current_user,
 getattr(current_user, 'email', 'no email'),
 ), exc_info=exc_info)

As you can see the indentation is quite ugly and the long list of formatting args makes it even worse.

Using textwrap.dedent helped the situation, but the formatting args is still problematic:

def log_exception(self, exc_info):
 self.logger.error(
 dedent('''Time: %s
 Path: %s
 HTTP Method: %s
 POST_ARGS: %s
 GET_ARGS: %s
 Client IP Address: %s
 User Agent: %s
 User Platform: %s
 User Browser: %s
 User Browser Version: %s
 Username: %s
 Email: %s''') % (datetime.now(),
 request.path,
 request.method,
 request.form,
 request.args,
 request.remote_addr,
 request.user_agent.string,
 request.user_agent.platform,
 request.user_agent.browser,
 request.user_agent.version,
 current_user,
 getattr(current_user, 'email', 'no email')),
 exc_info=exc_info
 )

Is this the best I can do?

Answer 1

How about this?

def log_exception(self, exc_info):
 msg = ''
 msg += 'Time: %s\n' % datetime.now()
 msg += 'Path: %s\n' % request.path
 msg += 'HTTP Method: %s\n' % request.method
 msg += 'POST_ARGS: %s\n' % request.form
 msg += 'GET_ARGS: %s\n' % request.args
 msg += 'Client IP Address: %s\n' % request.remote_addr
 msg += 'User Agent: %s\n' % request.user_agent.string
 msg += 'User Platform: %s\n' % request.user_agent.platform
 msg += 'User Browser: %s\n' % request.user_agent.browser
 msg += 'User Browser Version: %s\n' % request.user_agent.version
 msg += 'Username: %s\n' % current_user
 msg += 'Email: %s\n' % getattr(current_user, 'email', 'no email')
 self.logger.error(msg, exc_info=exc_info)

I guess, logging an exception doesn't happen every often, so efficiency shouldn't be a concern.

Alternatively, you can emulate variable interpolation and avoid formatting altogether:

now = datetime.now() 
email = getattr(current_user, 'email', 'no email')
msg = _('''\
 Time: {now}
 Path: {request.path}
 HTTP Method: {request.method}
 POST_ARGS: {request.form}
 GET_ARGS: {request.args}
 Client IP Address: {request.remote_addr}
 User Agent: {request.user_agent.string}
 User Platform: {request.user_agent.platform}
 User Browser: {request.user_agent.browser}
 User Browser Version: {request.user_agent.version}
 Username: {current_user}
 Email: {email}
''')
self.logger.error(dedent(msg), exc_info=exc_info)