How to check if python module exists and can be imported [duplicate]

Question

I am using debug toolbar with django and would like to add it to project if two conditions are true:

• settings.DEBUG is True
• module itself exists

It's not hard to do the first one

# adding django debug toolbar if DEBUG:     MIDDLEWARE_CLASSES += 'debug_toolbar.middleware.DebugToolbarMiddleware',     INSTALLED_APPS += 'debug_toolbar', 

But how do I check if module exists?

I have found this solution:

try:     import debug_toolbar except ImportError:     pass 

But since import happens somewhere else in django, I need if/else logic to check if module exists, so I can check it in settings.py

def module_exists(module_name):     # ??????  # adding django debug toolbar if DEBUG and module_exists('debug_toolbar'):     MIDDLEWARE_CLASSES += 'debug_toolbar.middleware.DebugToolbarMiddleware',     INSTALLED_APPS += 'debug_toolbar', 

Is there a way to do it?

Answer 1

You can use the same logic inside your function:

def module_exists(module_name):     try:         __import__(module_name)     except ImportError:         return False     else:         return True 

There is no performance penalty to this solution because modules are imported only once.