django在某处引发异常

Question

SOCIAL_AUTH_PIPELINE = (
    'social.pipeline.social_auth.associate_by_email',
)

by using the above code in settings.py i can avoid...

(1062, "Duplicate entry 'example@example.com' for key 'email'") error message.

But i searched online and i found this handy code to throw exception in desired html page:

[Code 1]: #backends.py

class MySocialAuthExceptionMiddleware(SocialAuthExceptionMiddleware):
    def process_exception(self, request, exception):
        msg = None
        if #no duplicate email:
            return HttpResponse("# catched exception")
        else:
            # processing msg here
            return render_to_response(# html, {msg}, context)

# settings.py

MIDDLEWARE_CLASSES = (
    'frontend.backends.MySocialAuthExceptionMiddleware'
)

My problem is solved by based on the above code. But in previously i worked with another one functionality with the following code and it is entirely different from the above concept.

[Code 2]:

def function(request):
    #actual code here
    return HttpResponse('msg here')

But while running the above code, and i got the error message like,

tuple index out of range in this MySocialAuthExceptionMiddleware ..

Actually this is not correct error message for the above code.. This message is related to the code of " [Code 1] ".

Then, how can i get the actual error message for " [Code 2] ".

Answer 1

You don't need to go through all this headache. Exceptions are not special in django, they are part of Python.

If you want to raise a custom exception - wherever you want to do so:

class MyException(Exception):
    pass

def function(request):
    raise MyException('msg here')

The problem you are facing is that in django, middleware is called on every request , even if the request is not "related" to that middleware.

So when writing middleware you need to keep in mind that it will be called for each and every request and it should handle these cases correctly.