python - TypeError：“NoneType”对象不可下标 Python Kivymd 和 MySql

Question

所以一切正常，值被添加到数据库中，但由于某种原因，它在给出以下错误后直接失败 - TypeError: 'NoneType' object is not subscriptable

我虽然可能是我在屏幕上显示它的方式，所以我删除了最后一点，看看它是否会顺利通过，但它仍然会产生同样的错误，尽我所能，但我的大脑一片空白，我得去睡觉了，任何帮助表示赞赏，迟来的复活节快乐！

Python代码 -

def add_student_now(self):
        spec_email = self.manager_screen.home.nav_drawer.grid_drawer.drawer_email.text
        student_first_name = self.manager_screen.add_student.firstname.text
        student_last_name = self.manager_screen.add_student.lastname.text
        student_notes = self.manager_screen.add_student.notes.text
        con = sql.connect(host="localhost", user="root", password="hipeople11", database="people")
        cur = con.cursor(buffered=True)
        query = "SELECT email, first_name, surname FROM teachers"
        cur.execute(query)
        for (email, first_name, surname) in cur:
            if email == spec_email: 
                full_name = first_name.lower() + surname.lower()
                print(full_name)
                print(spec_email)
                print("{}students".format(full_name))
                cur.execute("INSERT INTO {}students (studentfirstname, studentlastname, studentnotes) VALUES (%s,%s,%s)".format(full_name), (student_first_name, student_last_name, student_notes))
                con.commit()
                con.close()
                self.manager_screen.current = "home"
                student = student_first_name + " " + student_last_name
                #create label
                self.manager_screen.home.grid_home.s_home.h_student_list.add_widget(OneLineListItem(text=student)) ```

Kivy code-

    MDScreen:
        id: home
        name: "home"
        radius: [25, 0, 0, 0]
        grid_home: grid_home
        nav_drawer: nav_drawer
        
            
        MDGridLayout:
            id: grid_home
            h_toolbar : h_toolbar
            s_home: s_home
            ab_home: ab_home
            del_home: del_home
            cols: 1
            rows: 2
            MDToolbar:
                id: h_toolbar
                title: "NewArk Grading Systems"
                pos_hint: {'top':1.0}
                md_bg_color: 0,0,0,1
                elevation: 10
                left_action_items: [["menu", lambda x: nav_drawer.set_state("open")]]
            ScrollView:
                id: s_home
                name: "s_home"
                h_student_list: h_student_list
                do_scroll_x: False
                MDList:
                    id: h_student_list
    MDScreen:
        id: add_student
        name: "add_student"
        firstname: firstname
        lastname: lastname
        notes: notes
        radius: [25, 0, 0, 0]
        MDFloatLayout:
            MDLabel:
                text:'Enter Details'
                pos_hint: {'center_x':  0.965, 'center_y':0.6}
                bold: True
            MDRectangleFlatButton:
                text: 'Add Student'
                pos_hint:  {'center_x':0.5, 'center_y': 0.2}
                line_color: 0,0,0,1
                text_color: 0,0,0,1
                on_release: root.add_student_now()
            MDTextField:
                id: firstname
                hint_text: 'First Name'
                pos_hint:  {'center_x':0.5, 'center_y': 0.5}
                icon_right: 'smile'
                color_mode: 'custom'
                helper_text_mode: "on_focus"
                line_color_focus: 0, 0, 0, 1
                size_hint_x:None
            MDTextField:
                id: lastname
                hint_text: 'Last Name'
                pos_hint:  {'center_x':0.5, 'center_y': 0.4}
                icon_right: 'smile'
                color_mode: 'custom'
                helper_text_mode: "on_focus"
                line_color_focus: 0, 0, 0, 1
                size_hint_x:None
            MDTextField:
                id: notes
                hint_text: 'Notes'
                pos_hint:  {'center_x':0.5, 'center_y': 0.3}
                icon_right: 'smile'
                color_mode: 'custom'
                helper_text_mode: "on_focus"
                line_color_focus: 0, 0, 0, 1
                size_hint_x:None
                multiline : True

标签： pythonmysqlkivykivy-languagekivymd