Decorator - viewpoint mapping assertion error

Question

I have a flask app with several end points and I have written a decorator to log the end points for audit purpose. The decorator works fine when I tried with one end point but when I add the decorator to a second end point, I am facing assertion error

For Example, I have two end points to edit and delete

@route('/owners/<ownerid>/delete',methods=['DELETE'])
@logtrail()
def deleteOwner(ownerid):
     if request.method == 'DELETE':
         return jsonify({})

@route('/owners/<ownerid>/edit',methods=['PUT'])
@logtrail()
def editOwner(ownerid):
     if request.method == 'PUT':
         return jsonify({})

The decorator @logtrail works fine either for edit or delete edit point but the app fails to start if add the decorator to both end points

Decorator code is as below

def logtrail(usermsg=None):
    def decorator(func):
        def wrap(*args, **kwargs):
            print "Audit code goes here"
            return func(**kwargs)
        return wrap
    return decorator

Exact error which I get when I start the application is

AssertionError: View function mapping is overwriting an existing endpoint function: wrap

From error message, I get the name has to be unique like method names but how can I do that in a decorator?

Any suggestion will be helpful

Answer 1

Using a decorator without the wrap will rename the function, which will cause the issue you mentioned - since there will be more than one function with the same name.

(...) A decorator is a function that returns a function. The only thing you have to keep in mind when implementing something like this is to update the __name__, __module__ and some other attributes of a function. This is often forgotten, but you don’t have to do that by hand, there is a function for that that is used like a decorator (functools.wraps()).

(http://flask.pocoo.org/docs/0.11/patterns/viewdecorators/).

Try to change your decorator to the following:

from functools import wraps

def logtrail(usermsg=None):
    def decorator(func):
        @wraps(func)
        def wrap(*args, **kwargs):
            print "Audit code goes here"
            return func(**kwargs)
        return wrap
    return decorator