在Python中无法访问的函数-错误：未定义全局名称

Question

I'm new to Python programming and I'm stuck with the following error:

form="""
    <form method="post">
    What is your birthday?
    <br>

    <label> Month
        <input type="text" name="month">
    </label

    <label> Day
        <input type="text" name="day">
    </label>

    <label> Year
        <input type="text" name="year">
    </label>

    <br>
    <br>
    <input type="submit">
</form>
"""

class MainPage(webapp2.RequestHandler):

def get(self):
        self.response.out.write(form)

def valid_day(day):
        if day and day.isdigit():
            day = int(day)
            if day > 0 and day <= 31:
                return day

def valid_year(year):
        if year and year.isdigit():
            year = int(year)
            if year > 1899 and year < 2021:
                return year
def post(self):
        user_day = valid_day(self.request.get('day'))
        user_year = valid_year(self.request.get('year'))

I'm told that global name 'valid_day' is not defined. Can anybody tell me where is the fault? I think I defined the function valid_day / valid_year above so it should be accessible, or not?

Answer 1

It appears by your use of self as a parameter to the post function that this code is inside a class.

In that case, you need to use self to access the methods. (Normally your assumption about scoping and defining functions above the call would be correct.)

Rewrite your post function as follows:

def post(self):
    user_day = self.valid_day(self.request.get('day'))
    user_year = self.valid_year(self.request.get('year'))