Kivy AttributeError: 'NoneType' 对象没有属性 'get_screen'

Question

我正在尝试根据对我的数据库的查询结果使用多个Buttons初始化Screen ，但我收到了AttributeError 。 我认为这是因为当我初始化我的应用程序时没有Information Screen并阅读这个答案： AttributeError: 'NoneType' object has no attribute 'current'我需要使用Clock来延迟我的Finder类的初始化，所以我的Information类有是时候创建了，但我不太确定如何在__init__方法中执行此操作，或者这是否是正确的方法？

class Finder(Screen):
    layout_profiles = ObjectProperty(None)

    def __init__(self, **kwargs):
        super(Finder, self).__init__(**kwargs)
        self.mydb = mysql.connector.connect(host="localhost", user="root", passwd="", database="")
        self.cur = self.mydb.cursor(buffered=True)
        self.cur.execute("SELECT gender, age, name FROM users WHERE location = %s AND date_of_visit = %s",
                         (self.manager.get_screen('information').location.text,
                          self.manager.get_screen('information').date))
        self.mydb.commit()
        self.results = cur.fetchall()
        self.cur.close()
        self.mydb.close()
        if self.results:
            for result in self.results:
                if result[0] == "male":
                    male_btn = MaleButton(text="{}, {}".format(result[1], result[2]))
                    self.layout_profiles.add_widget(male_btn)
                elif result[0] == "female":
                    female_btn = FemaleButton(text="{}, {}".format(result[1], result[2]))
                    self.layout_profiles.add_widget(female_btn)
                else:
                    unknown_btn = NoGenderButton(text="{}, {}".format(result[1], result[2]))
                    self.layout_profiles.add_widget(unknown_btn)

错误

line 249, in __init__
     (self.manager.get_screen('information').location.text,
 AttributeError: 'NoneType' object has no attribute 'get_screen'

Answer 1

, dt 这是在屏幕初始化后执行所有东西的一种方式

class Finder(Screen):
    layout_profiles = ObjectProperty(None)

    def __init__(self, **kwargs):
        super(Finder, self).__init__(**kwargs)
        self.mydb = mysql.connector.connect(host="localhost", user="root", passwd="", database="")
        self.cur = self.mydb.cursor(buffered=True)
        Clock.schedule_once(self.do_stuff)

    def do_stuff(self, dt):
        self.cur.execute("SELECT gender, age, name FROM users WHERE location = %s AND date_of_visit = %s",
                         (self.manager.get_screen('information').location.text,
                          self.manager.get_screen('information').date))
        self.mydb.commit()
        self.results = self.cur.fetchall()
        self.cur.close()
        self.mydb.close()
        if self.results:
            for result in self.results:
                if result[0] == "male":
                    male_btn = MaleButton(text="{}, {}".format(result[1], result[2]))
                    self.layout_profiles.add_widget(male_btn)
                elif result[0] == "female":
                    female_btn = FemaleButton(text="{}, {}".format(result[1], result[2]))
                    self.layout_profiles.add_widget(female_btn)
                else:
                    unknown_btn = NoGenderButton(
                        text="{}, {}".format(result[1], result[2]))
                    self.layout_profiles.add_widget(unknown_btn)