为什么调用函数的返回值赋值给变量之后就变成noneType了

Question

tkinter selenium ttk.button.common调用函数

def cut_value():
    user = user_down_menu.get()
    if user in name:
        return name[user]

    ins_click1 = tkinter.Button(win, text='登录', width=12, command=main_pro)
    ins_click1.pack()

def main_pro():
    list = []
    for item in cut_value():
        print(item)
        list.append(item)
    # 将路径实例化为一个Service对象
    path = Service("C:\\Users\\Administrator\\AppData\\Local\\Google\\Chrome\\Application\\chromedriver.exe")

    url = 'https://ssp.rails.cn/#/login'
    # 打开谷歌浏览器
    '''
    executable_path被重构进了service.py中，我们可以实例化一个Service对象来表示浏览器驱动的路径
    driver = webdriver.Chrome(executable_path=path)
    '''

   driver.find_element_by_xpath('//*[@id="divCenterRight"]/div/form/div[1]/div/div[2]/input').send_keys(list[0])   
    time.sleep(2)
    driver.find_element_by_xpath('//*[@id="divCenterRight"]/div/form/div[2]/div/div[2]/input').send_keys(list[1])      #输入密码
    time.sleep(2)

C:\Users\Administrator\PycharmProjects\web_AutoLogin\venv\Scripts\python.exe C:/Users/Administrator/PycharmProjects/web_AutoLogin/main.py

Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\Administrator\AppData\Local\Programs\Python\Python39\lib\tkinter_init.py", line 1884, in call
return self.func(*args)
File "C:\Users\Administrator\PycharmProjects\web_AutoLogin\main.py", line 11, in main_pro
for item in cut_value():
TypeError: 'NoneType' object is not iterable
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\Administrator\AppData\Local\Programs\Python\Python39\lib\tkinter_init.py", line 1884, in call
return self.func(*args)
File "C:\Users\Administrator\PycharmProjects\web_AutoLogin\main.py", line 11, in main_pro
for item in cut_value():
TypeError: 'NoneType' object is not iterable
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\Administrator\AppData\Local\Programs\Python\Python39\lib\tkinter_init.py", line 1884, in call
return self.func(*args)
File "C:\Users\Administrator\PycharmProjects\web_AutoLogin\main.py", line 11, in main_pro
for item in cut_value():
TypeError: 'NoneType' object is not iterable
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\Administrator\AppData\Local\Programs\Python\Python39\lib\tkinter_init.py", line 1884, in call
return self.func(*args)
File "C:\Users\Administrator\PycharmProjects\web_AutoLogin\main.py", line 11, in main_pro
for item in cut_value():
TypeError: 'NoneType' object is not iterable

想分别取出cut_value()函数返回的数组的下标0值和下标1值

Answer 1

函数cut_value()k中如果if条件满足返回结果，条件不满足，返回的就是None,在第11行调用时报错（None类型对象不可迭代）。这样试试：

def cut_value():
    user = user_down_menu.get()
    if user in name:
        return name[user]
    else:
        return ''