Best Web Framework Features?

[amadan]

One thing I like in frameworks is being able to make it handle getting all the 
values from the request that I need without me needing to handle things like 
the value missing. e.g. I can annotate a route in some way that it is expecting 
a header with the name "Foo" and it will throw a 400 if its missing (and this 
happens before my handler is even ran)