Python - 嵌套ifs的相同代码

Question

在Django中,处理表单的规范方法是:

if request.method == 'POST':
    form = SomeForm(request.POST)
    if form.is_valid():
        use the form data

我想执行相同的代码,无论是没有POST还是表单无效 - 这是几行代码,所以我想知道是否有一个更好的方法来做这个比两个重复的else块(一个用于内部if和one for outer)？

Answer 1

使用单独的功能:

if request.method != 'POST':
    return do_something_function_for_invalid(request)

form = SomeForm(request.POST)
if not form.is_valid():
    return do_something_function_for_invalid(request)

# do something

然后定义do_something_function_for_invalid()为:

def do_something_function_for_invalid(request):
    # do something

    return response

或者,使用异常处理:

try:
    if request.method != 'POST':
        raise ValueError('invalid form')

    form = SomeForm(request.POST)
    if not form.is_valid():
        raise ValueError('not a POST request')

     # do something
except ValueError as ve:
    # handle ve exception, ve.args[0] is the error message

Answer 2

一种非常简洁的方法,不需要单独的功能,也不重复条件:

form = SomeForm(request.POST) if request.method == 'POST' else None

if form and form.is_valid():
    # do your valid-submission stuff
else:
    # do your invalid-submission stuff