Python decorator to check for POST parameters on Django

Question

I have code that read like this to check if POST parameters are included on the request:

def login(request):
    required_params = frozenset(('email', 'password'))
    if required_params <= frozenset(request.POST):
        # 'email' and 'password' are included in the POST request
        # continue as normal
        pass
    else:
        return HttpResponseBadRequest()

When the list of required POST parameters is big, this code gets messy. What I would like to do is something like:

@required_POST_params('email', 'password')
def login(request):
    # 'email' and 'password' are here always!
    pass

Then I'm confident that both 'email' and 'password' POST parameters are included in the request, because if not, the request would automatically return HttpResponseBadRequest().

Is there a way that Django allows me to do this, and if it doesn't, how can I do it by myself with a decorator?

Answer 1

You would need a custom decorator, but you can take require_http_methods as a base example:

def require_post_params(params):
    def decorator(func):
        @wraps(func, assigned=available_attrs(func))
        def inner(request, *args, **kwargs):
            if not all(param in request.POST for param in params):
                return HttpResponseBadRequest()
            return func(request, *args, **kwargs)
        return inner
    return decorator

Example usage:

@require_post_params(params=['email', 'password'])
def login(request):
    # 'email' and 'password' are here always!
    pass

FYI, require_http_methods source code.