调用tkinter窗口变量以便可以在另一个函数中使用

Question

对于这段代码，我的目的是添加一个函数来添加用户输入到数据库中的数据。我已经设置了一个函数来创建用户界面，让他们输入数据，还有一个函数来检索数据。但是，我收到一条错误消息，说DeliveryInterface变量尚未定义。有没有办法让add data函数从上一个函数中识别DeliveryInterface变量？我附加导致问题的代码段。你知道吗

        def InputScreen():
             DeliveryInterface = tkinter.Tk() #creates the interface for the input screen
             DeliveryInterface.title('Input New Data') #gives the new window a title
             DeliveryInterface.geometry('400x500') #sets the default size of the window as 400 x 500
             DeliveryInterface.maxsize(400, 500) #sets the maximum size of the interface as 400 x 500
             DeliveryInterface.configure(background='#0092FF') #sets the background colour of the inteface to the light blue as seen in the main menu interface
            (.......)
            StockIDLabel = tkinter.Label(DeliveryInterface, text='Stock ID', font=('Helvetica', 16))  # creates a label that tells the user that the next box is associated with the stock id
            StockIDLabel.place(x=30, y=60, height=22, width=200)

            StockID_entry = tkinter.Entry(DeliveryInterface, font=('Helvetica', 16))  # creates the entry box for the stock ID
            StockID_entry.place(x=250, y=60, height=22, width=100)
            (...........)
         def addingNewStock():
             StockID = 0 #Initialises the stock ID
             StockID = DeliveryInterface.StockID_entry.get() #intended to get the data from the entrybox, however, i get an error message say that DeliveryInterface hasnt been defined
            print (StockID) #prints the stockID so that i now if the variable has been changed.

我希望这是所有需要的信息，谢谢

Answer 1

必须使DeliveryInterface全局：

    def InputScreen():
         global DeliveryInterface
         DeliveryInterface = tkinter.Tk() #creates the interface for the input screen
         DeliveryInterface.title('Input New Data') #gives the new window a title
         DeliveryInterface.geometry('400x500') #sets the default size of the window as 400 x 500
         DeliveryInterface.maxsize(400, 500) #sets the maximum size of the interface as 400 x 500
         DeliveryInterface.configure(background='#0092FF') #sets the background colour of the inteface to the light blue as seen in the main menu interface
        (.......)
        StockIDLabel = tkinter.Label(DeliveryInterface, text='Stock ID', font=('Helvetica', 16))  # creates a label that tells the user that the next box is associated with the stock id
        StockIDLabel.place(x=30, y=60, height=22, width=200)

        StockID_entry = tkinter.Entry(DeliveryInterface, font=('Helvetica', 16))  # creates the entry box for the stock ID
        StockID_entry.place(x=250, y=60, height=22, width=100)
        (...........)
     def addingNewStock():
         StockID = 0 #Initialises the stock ID
         StockID = DeliveryInterface.StockID_entry.get() #intended to get the data from the entrybox, however, i get an error message say that DeliveryInterface hasnt been defined
        print (StockID) #prints the stockID so that i now if the variable has been changed.

另一个选择是使用python3的nonlocal关键字。你知道吗

Answer 2

您所面临的问题是变量有其作用域-您已将DeliveryInterface定义为存在于InputScreen（）中-而它不会存在于其他任何地方。你知道吗

您可以选择以下几种方法来解决此问题：

使其成为全局变量。这通常是不赞成的，被认为是一个坏的做法，但仍然可以是合理的。你知道吗

使InputScreen成为一个类，该类将具有初始化和添加新库存的方法。通过这样做，类将记住它的状态——变量的值。你知道吗

或者将DeliveryInterface作为参数传递给addingNewStock（）函数。如果您正从函数InputScreen（）调用此函数，那么这将是最简单的解决方案。你知道吗