Question

我一直试图从我的 sqlite 数据库中创建一个列表。该列表可以实时追加。一切正常，直到我添加了“if”语句以便实时添加更多列表项。如果我的数据库已填充，即使使用“if”语句，代码也能正常工作，但如果我的数据库没有值，则会发生以下错误

local variable 'name' referenced before assignment

这是代码

def on_start(self):
    list_item = ObjectProperty
    list_item = [] 
    self.connection = sqlite3.connect('friend_list.db')
    self.cursor = self.connection.cursor() 
    self.cursor.execute("""SELECT * FROM friend_list ;""")
    self.connection.row_factory = lambda cursor, row: row[0]
    friends = self.connection.execute('SELECT name FROM friend_list').fetchall()
    for name in friends:
        print(name)
        button = OneLineAvatarIconListItem(text = name,on_press=lambda widget:self.change_screen("Chat_Screen"))
        self.root.ids["Chat_List"].ids["list"].add_widget(button)
        button.bind(on_press=self.press)
        list_item.append(name)

    
    if name not in list_item:  #this is the condition which is causing error
        a = list_item[-1]
        button = OneLineAvatarIconListItem(text = (a),on_press=lambda widget:self.change_screen("Chat_Screen"))
        button.bind(on_press=self.press)
        self.root.ids["Chat_List"].ids["list"].add_widget(button)
        button.bind(on_press=self.press)
        print(list_item)

Answer 1

def on_start(self):
    list_item = ObjectProperty
    list_item = [] 
    self.connection = sqlite3.connect('friend_list.db')
    self.cursor = self.connection.cursor() 
    self.cursor.execute("""SELECT * FROM friend_list ;""")
    self.connection.row_factory = lambda cursor, row: row[0]
    friends = self.connection.execute('SELECT name FROM friend_list').fetchall()
    for name in friends:
        print(name)
        button = OneLineAvatarIconListItem(text = name,on_press=lambda widget:self.change_screen("Chat_Screen"))
        self.root.ids["Chat_List"].ids["list"].add_widget(button)
        button.bind(on_press=self.press)
        list_item.append(name)

    
        if name not in list_item:  #this is the condition which is causing error
            a = list_item[-1]
            button = OneLineAvatarIconListItem(text = (a),on_press=lambda widget:self.change_screen("Chat_Screen"))
            button.bind(on_press=self.press)
            self.root.ids["Chat_List"].ids["list"].add_widget(button)
            button.bind(on_press=self.press)
            print(list_item)

if 条件中缺少缩进。

在 KivyMD 应用程序中赋值之前引用的局部变量“名称”

1 个答案: