默认选中的单选按钮未分配值，导致NameError。

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英文:

Default selected radio button isn't assigned a value resulting in NameError

问题

我正在尝试使用Python的tkinter创建一个带有Radiobuttons的GUI。尽管我已经在选择函数内指定了相关变量（material_category）为全局，但我仍然无法检索所选选项的值。

当我按“Enter Data”按钮运行代码时，没有选择除默认选择（即“Common Steel”）之外的不同选项，我会收到以下错误消息：

“NameError: name 'material_category' is not defined”

只有当用户根本不触碰单选按钮窗口并立即按“Enter”按钮时，才会出现此错误。如果用户按下任何单选按钮，代码就会正常工作。

但我感到困惑的是，为什么起始单选按钮（即“Common Steel”）似乎被选中但未被分配一个值（换句话说，为什么x未被分配值0，即使该选项被选中）。是否有办法将x的默认值设置为0？

我该如何修改代码，以使其在没有错误或异常处理的情况下运行？是否有更好、更紧凑的编码方式，以省略检查选择的material_category_selection()函数？

Python版本：3.11.1
IDE：VSCodium

英文:

I am trying to create a GUI with radiobuttons using tkinter from python. I am having trouble retrieving the value of the selected option, even though I have specified the variable (material_category) in question to be global inside the selection function.

When I press the Enter Data button to run my code without selecting a different option other than the one appearing selected by default (i.e. Common Steel), I am greeted with this error:

"NameError: name 'material_category' is not defined"

This error appears only if the user doesn't fiddle at all with the radio-button windows and presses the Enter button button straight away. In case the user gets to press any radio button the code works fine.

I am bamboozled though, as to why the starting radio button (i.e. "Common Steel") appears selected but is not assigned a value (in other words why x is not assigned the value of 0, even though that option appears selected). Is there a way I could assign the default value of 0 to x?

What can I do to actually make this code run without errors or handling an exception? Is there a better, more compact way to code this in order to omit the material_category_selection() function that checks the selection?

Python version: 3.11.1
IDE: VSCodium

  1. import tkinter
  2. from tkinter import *
  3. from tkinter import ttk
  4. from tkinter import messagebox
  6. def enter_data():
  7.     print(material_category)
  8.     window.quit()
  10. #GUI 
  12. window = tkinter.Tk()
  13. window.title("Stress Data Entry")
  14. window.resizable(0,0)
  16. frame = tkinter.Frame(window)
  17. frame.pack()
  20. #MATERIAL CATEGORY
  22. material_category_frame =tkinter.LabelFrame(frame, text="Material Category")
  23. material_category_frame.grid(row= 0, column=1, padx=20, pady=10)
  25. material_category_option=["Common Steel","Soldering Steel", "Carburized Steel", "Upgraded Steel", "Nitrogenous Steel"]
  27. x=IntVar()
  29. def material_category_selection():
  30.     global material_category
  31.     if(x.get()==0):
  32.         material_category="commonsteel"
  33.     elif(x.get()==1):
  34.         material_category="solderingsteel"
  35.     elif(x.get()==2):
  36.         material_category="carburizedsteel"
  37.     elif(x.get()==3):
  38.         material_category="upgradedsteel"
  39.     elif(x.get()==4):
  40.         material_category="nitrogenoussteel"
  41.     else:
  42.         tkinter.messagebox.showwarning(title="Error!", message="Something went wrong!")
  44. for index in range(len(material_category_option)):
  45.     radiobutton = Radiobutton(material_category_frame, 
  46.     text=material_category_option[index], 
  47.     variable=x, 
  48.     value=index,
  49.     padx=20,
  50.     pady=10,
  51.     command=material_category_selection)
  53. for widget in material_category_frame.winfo_children():
  54.     widget.grid_configure(padx=10, pady=5)
  56. button = tkinter.Button(frame, text="Enter Data", command= enter_data)
  57. button.grid(row=3, column=1, sticky="news", padx=20, pady=10)
  59. window.mainloop()

答案1

得分: 1

错误是由于 material_category_selection() 尚未执行，因此 material_category 未被创建。

我建议将 material_category_selection() 的逻辑放入 enter_data() 中，因为我看不到 material_category_selection() 有任何必要性：

  1. # 移除通配符导入，因为不建议使用
  2. import tkinter
  3. from tkinter import messagebox
  5. def enter_data():
  6.     global material_category
  7.     try:
  8.         if(x.get()==0):
  9.             material_category="普通钢"
  10.         elif(x.get()==1):
  11.             material_category="焊接钢"
  12.         elif(x.get()==2):
  13.             material_category="渗碳钢"
  14.         elif(x.get()==3):
  15.             material_category="升级钢"
  16.         elif(x.get()==4):
  17.             material_category="含氮钢"
  18.         else:
  19.             raise Exception("出现了问题！")
  20.         print(material_category)
  21.         window.destroy()
  22.     except Exception as ex:
  23.         messagebox.showwarning(title="错误！", message=ex)
  25. # GUI
  27. window = tkinter.Tk()
  28. window.title("应力数据输入")
  29. window.resizable(0, 0)
  31. frame = tkinter.Frame(window)
  32. frame.pack()
  34. material_category_frame =tkinter.LabelFrame(frame, text="材料类别")
  35. material_category_frame.grid(row= 0, column=1, padx=20, pady=10)
  37. material_category_option=["普通钢", "焊接钢", "渗碳钢", "升级钢", "含氮钢"]
  39. x = tkinter.IntVar() # 默认值将设置为0
  40. for index, text in enumerate(material_category_option):
  41.     radiobutton = tkinter.Radiobutton(material_category_frame,
  42.                                       text=text,
  43.                                       variable=x,
  44.                                       value=index,
  45.                                       padx=20,
  46.                                       pady=10) # 移除了command选项
  47.     radiobutton.grid_configure(padx=10, pady=5, sticky="w")
  49. button = tkinter.Button(frame, text="输入数据", command= enter_data)
  50. button.grid(row=3, column=1, sticky="news", padx=20, pady=10)
  52. window.mainloop()
英文:

The error is caused by that material_category_selection() has not been executed yet so material_category is not created.

I would suggest to put the logic of material_category_selection() into enter_data() as I don't see any necessity of material_category_selection():

  1. # removed wildcard import as it is not recommended
  2. import tkinter
  3. from tkinter import messagebox
  5. def enter_data():
  6.     global material_category
  7.     try:
  8.         if(x.get()==0):
  9.             material_category="commonsteel"
  10.         elif(x.get()==1):
  11.             material_category="solderingsteel"
  12.         elif(x.get()==2):
  13.             material_category="carburizedsteel"
  14.         elif(x.get()==3):
  15.             material_category="upgradedsteel"
  16.         elif(x.get()==4):
  17.             material_category="nitrogenoussteel"
  18.         else:
  19.             raise Exception("Something went wrong!")
  20.         print(material_category)
  21.         window.destroy()
  22.     except Exception as ex:
  23.         messagebox.showwarning(title="Error!", message=ex)
  25. #GUI
  27. window = tkinter.Tk()
  28. window.title("Stress Data Entry")
  29. window.resizable(0, 0)
  31. frame = tkinter.Frame(window)
  32. frame.pack()
  34. material_category_frame =tkinter.LabelFrame(frame, text="Material Category")
  35. material_category_frame.grid(row= 0, column=1, padx=20, pady=10)
  37. material_category_option=["Common Steel", "Soldering Steel", "Carburized Steel", "Upgraded Steel", "Nitrogenous Steel"]
  39. x = tkinter.IntVar() # value 0 will be set by default
  40. for index, text in enumerate(material_category_option):
  41.     radiobutton = tkinter.Radiobutton(material_category_frame,
  42.                                       text=text,
  43.                                       variable=x,
  44.                                       value=index,
  45.                                       padx=20,
  46.                                       pady=10) # removed command option
  47.     radiobutton.grid_configure(padx=10, pady=5, sticky="w")
  49. button = tkinter.Button(frame, text="Enter Data", command= enter_data)
  50. button.grid(row=3, column=1, sticky="news", padx=20, pady=10)
  52. window.mainloop()

答案2

得分: 0

在你的情况下，如果用户没有点击“Radiobutton”而点击了“'Enter Data'”，它会调用“enter_data()”，但你从未定义了“material_category”，会导致“NameError”。因此，你可以使用错误处理：

  1. def enter_data():
  2.     try:
  3.         print(material_category)
  4.         window.quit()
  5.     except NameError:
  6.         tkinter.messagebox.showwarning(title="Error!", message="Please provide a material!")
英文:

In your case, if the user does not click a Radiobutton but clicks 'Enter Data', it calls enter_data(), but you never defined material_category, giving a NameError. So, you can use error handling:

  1. def enter_data():
  2. try:
  3. print(material_category)
  4. window.quit()
  5. except NameError:
  6. tkinter.messagebox.showwarning(title="Error!", message="Please provide a material!")

huangapple
  • 本文由 发表于 2023年7月14日 04:00:48
  • 转载请务必保留本文链接：https://go.coder-hub.com/76682861.html
  • python
  • radio-button
  • tkinter
  • tkinter-entry
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