Python：“NoneType”对象没有“get”属性

Question

我正在使用 tkinter 在 python 中创建一个 GUI，但在运行它时遇到了问题。我有一个输入框小部件、一个单选按钮小部件和一个按钮小部件。当我按下按钮时，我想要的是用户在输入框中输入一个数字并从单选按钮列表中选择一个选项。当用户按下按钮时，我希望检索值并将其显示在另一个框架中以进行测试。我得到的是当按钮被按下时，我得到错误'NoneType' object has no attribute 'get'。错误是指输入框中的值：self.tune_entry

我的代码如下：

SA_main.py

import os
import tkinter as tk
from tkinter import ttk
from tkinter import font
import SA_gui

def main():

    x_vals = [0,1,2,3,4]
    y_vals = [0,1,2,3,4]

    root = SA_gui.tk.Tk()
    UI = SA_gui.Window(root, x_vals, y_vals)

    root.mainloop()


if __name__ == "__main__":
    main()

SA_gui.py

import os
import tkinter as tk
from tkinter import ttk
from tkinter import font

# Class to define, setup, and build the GUI
class Window:

    # Dimensions of the GUI
    HEIGHT = 600
    WIDTH = 1200

    # Colors for main layout
    bg_color = "#B0E0E6"
    frame_color1 = "#73B1B7"
    white_color = "#FFFFFF"

    def __init__(self, master, x_vals, y_vals):

        # Take in the lists of files for later use
        self.x_vals = x_vals
        self.y_vals = y_vals

        #--------------------------------------------------------------

        # Define and create the window
        self.master = master
        master.title("Signal Analysis")
        master.geometry("{}x{}".format(Window.WIDTH, Window.HEIGHT))

        # Create and place the background frame
        self.bg_frame = tk.Frame(self.master, bg=Window.bg_color, bd=5)
        self.bg_frame.place(relwidth=1, relheight=1)

        # Create the main title
        self.main_title = tk.Label(self.bg_frame, text="Software Defined Radio Signal Analysis", 
            bg=Window.bg_color, font=("Courier", 14))
        self.main_title.pack(side="top")

        #--------------------------------------------------------------

        # Create and place the frame for tuning
        self.tune_frame = tk.Frame(self.bg_frame, bg=Window.frame_color1, bd=4)
        self.tune_frame.place(relx=0.05, rely=0.1, relwidth=0.2428, relheight=0.8)

        # Create and place the title for the tuning frame
        self.tune_title = tk.Label(self.tune_frame, text="Tune", bg=Window.frame_color1, font= 
            ("Courier", 11))
        self.tune_title.place(relwidth=1, anchor="nw")

        # Create and place the contents of the tuning frame
        self.tune_cont = tk.Frame(self.tune_frame, bg=Window.white_color, bd=4)
        self.tune_cont.place(relx=0.05, rely=0.05, relwidth=0.9, relheight=0.925)

        #Label for frequency entry
        self.tune_label = tk.Label(self.tune_cont, text='Enter carrier frequency: (kHz)', 
            bg=Window.white_color)
        self.tune_label.place(relx=0.025, rely=0)

        #Entry Box for frequency entry
        self.tune_entry = tk.Entry(self.tune_cont)
        self.tune_entry.place(relx=0.025, rely=0.075, relwidth=0.95, relheight=0.05)

        #Label for divider
        self.tune_div = ttk.Separator(self.tune_cont, orient="horizontal")
        self.tune_div.place(rely=0.175, relwidth=1)

        #Label for display mode
        self.disp_label = tk.Label(self.tune_cont, text='Select Display:', bg=Window.white_color)
        self.disp_label.place(relx=0.025, rely=0.2)

        #Variable for radiobuttons
        self.var = tk.IntVar(self.tune_cont).set("1")

        #Radio Button for Spectral Analysis
        self.SA_select = tk.Radiobutton(self.tune_cont, text="Spectral 
            Analysis",bg=Window.white_color, padx=20, variable=self.var, value=1)
        self.SA_select.place(relx=0.025, rely=0.275)

        #Radio Button for Option 2
        self.opt2_select = tk.Radiobutton(self.tune_cont, text="Option 2",bg=Window.white_color, 
            padx=20, variable=self.var, value=2)
        self.opt2_select.place(relx=0.025, rely=0.35)

        #Radio Button for Option 3
        self.opt3_select = tk.Radiobutton(self.tune_cont, text="Option 3",bg=Window.white_color, 
            padx=20, variable=self.var, value=3)
        self.opt3_select.place(relx=0.025, rely=0.425)


        #Button for selection
        self.tune_button = ttk.Button(self.tune_cont, text="Enter", command=lambda: 
            self.print_selected(self.var.get(), self.tune_entry.get()))
        self.tune_button.place(relx= 0.775, rely=0.9, relwidth=0.2, relheight=0.075)

        #-----------------------------------------------------------------

        # Create and place the frame for the plot
        self.plot_frame = tk.Frame(self.bg_frame, bg=Window.frame_color1, bd=4)
        self.plot_frame.place(relx=0.3428, rely=0.1, relwidth=0.6071, relheight=0.8)

        # Create and place the title for the plot frame
        self.plot_title = tk.Label(self.plot_frame, text="Plot", bg=Window.frame_color1, font= 
            ("Courier", 11))
        self.plot_title.place(relwidth=1, anchor="nw")

        # Create and place the contents of the plot frame
        self.plot_cont = tk.Frame(self.plot_frame, bg=Window.white_color, bd=4)
        self.plot_cont.place(relx=0.025, rely=0.05, relwidth=0.95, relheight=0.925)



    def print_selected(self, disp, freq):
        if disp == 1:
            disp_mode = "Spectral Analysis"
        elif disp == 2:
            disp_mode = "Option 2"
        else:
            disp_mode = "Option 3"

        #Label for this test
        self.prnt_label = tk.Label(self.plot_cont, text="Display: " + disp_mode + ", Center Freq: " + 
            freq, bg=Window.white_color)
        self.prnt_label.place(relx=0.025, rely=0.2)

非常感谢任何帮助解决此问题！

Answer 1

考虑这段代码：

self.var = tk.IntVar(self.tune_cont).set("1")

无论何时执行x=y().z()，python 都会将z() 的返回值分配给x。因此，在您的代码中，您将.set("1") 的结果分配给self.var。 set 方法返回 None 所以 self.var 是 None。因此，当您稍后尝试调用self.var.get() 时，它与调用None.get() 相同。

如果要在创建时初始化变量，则无需调用set。此外，虽然它可以传递字符串，但如果您设置 IntVar，您确实应该将其设置为整数。

self.var = tk.IntVar(value=1)