tkinter无法将条目字符串转换为int

Question

我在一个类（StartPage）中有一个条目小部件，我必须在其中输入数字，输入保存在一个通用类（Variabili）中，该类可以从另一个类（FirstPage）访问。根据这个数字，我必须说出n个标签（其中n是我在上一页中输入的数字）。为此，我使用了for循环：for i in range(0, int(number))。问题是： 我一直收到这个错误：TypeError: IntVar() missing 1 required positional argument: 'name'

下面是代码：

import tkinter as tk                # python 3
from tkinter import font as tkfont
from typing_extensions import IntVar  # python 3


class SampleApp(tk.Tk):

    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)

        self.title_font = tkfont.Font(family='Helvetica', size=18, weight="bold", slant="italic")

        # the container is where we'll stack a bunch of frames
        # on top of each other, then the one we want visible
        # will be raised above the others
        container = tk.Frame(self)
        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        

        self.frames = {}
        for F in (StartPage, PageOne):
            page_name = F.__name__
            frame = F(parent=container, controller=self)
            self.frames[page_name] = frame

            # put all of the pages in the same location;
            # the one on the top of the stacking order
            # will be the one that is visible.
            frame.grid(row=0, column=0, sticky="nsew")

        self.show_frame("StartPage")

    def show_frame(self, page_name, *args):
        '''Show a frame for the given page name'''
        frame = self.frames[page_name]
        frame.tkraise()

    def get_page(self, classname):
        '''Returns an instance of a page given it's class name as a string'''
        for page in self.frames.values():
            if str(page.__class__.__name__) == classname:
                return page
        return None



class Variabili: 
    numero_finanziatori = tk.IntVar()
    
class StartPage(tk.Frame, Variabili):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller

        
        #label = tk.Label(self, text="Start Page: insert value")
        #label.pack(side="top", fill="x", pady=10)
        #self.some_input = tk.IntVar()
        #self.some_entry = tk.Entry(self, width=8, textvariable=self.some_input).pack()
        

        self.some_input = tk.StringVar()
        self.some_entry = tk.Entry(self, width=8, textvariable=Variabili.numero_finanziatori)
        self.some_entry.insert(0, "1")
        self.some_entry.pack()
        Variabili.numero_finanziatori = self.some_entry.get()
        
        button1 = tk.Button(self, text='Next Page', command=lambda: controller.show_frame("PageOne"))
        button1.pack()

class PageOne(tk.Frame, Variabili):   

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller

        
        labels_finanziatori = {
        'principale': [],
        'capitale_investito': [], 
        'tasso': [], 
        'tempo': []
        }
        dict_finanziatori = {
        'numero': [],
        'capitale_investito': [], 
        'tasso': [], 
        'tempo': [],
        }
        Finanziatore_Semplice = []

        k = 0

        for i in range(0, int(Variabili.numero_finanziatori)): 
            #MAIN label del finanziatore
            labels_finanziatori['principale'].append(tk.Label(self, text="Dati finanziatore numero "+str(i+1) +":\n"))
            labels_finanziatori['principale'][i].grid(row=i*(k+1), column = 0)
            k = k+1
            button = tk.Button(self, text="Go to the start page",
                           command=lambda: controller.show_frame("StartPage")).grid()

if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()

这是我得到的回溯：

File "c:/Users/trevi/Documents/WorkInProgress/Python/V0_3/backbone4.py", line 50, in <module>
    class Variabili:
  File "c:/Users/trevi/Documents/WorkInProgress/Python/V0_3/backbone4.py", line 51, in Variabili
    numero_finanziatori = tk.IntVar()
  File "C:\Users\trevi\Anaconda\Anaconda3\lib\tkinter\__init__.py", line 502, in __init__
    Variable.__init__(self, master, value, name)
  File "C:\Users\trevi\Anaconda\Anaconda3\lib\tkinter\__init__.py", line 317, in __init__
    self._root = master._root()
AttributeError: 'NoneType' object has no attribute '_root'

Answer 1

IntVar继承自Variable class

from inspect import signature
import tkinter


print("\n  - IntVar Method Resolution Order   -\n")

print(tkinter.IntVar.mro())

print("\n  - __init__ signature   -\n")

print("Variable:", signature(tkinter.Variable.__init__))
print("IntVar:", signature(tkinter.IntVar.__init__))

输出：

  - IntVar Method Resolution Order   -

[<class 'tkinter.IntVar'>, <class 'tkinter.Variable'>, <class 'object'>]

  - __init__ signature   -

Variable: (self, master=None, value=None, name=None)
IntVar: (self, master=None, value=None, name=None)

关键是调用IntVar（）需要一个主窗口（或根窗口）

从Variable class开始：

if not master:
    master = _get_default_root('create variable')
self._root = master._root()
self._tk = master.tk

此错误的原因是调用IntVar时找不到默认根。 如果root已在脚本中声明，则通常不将其指定为IntVar参数

import tkinter


print("\n  - root   -\n")

root = tkinter.Tk()
print(root.tk)
print("is _default_root:", tkinter._default_root is root)

print("\n  - IntVar   -\n")

var = tkinter.IntVar()
print(var._tk)

输出：

  - root   -

<_tkinter.tkapp object at 0x00000080E160E7B0>
is _default_root: True

  - IntVar   -

<_tkinter.tkapp object at 0x00000080E160E7B0>

脚本中root = tkinter.Tk()的类似物是app = SampleApp()。这就是为什么这些变量在与SampleApp关联的类中工作

---

但是问题不是这个错误，而是PageOne类中的标签是根据在StartPage类的条目中输入的值形成的

在应用程序中，所有帧都在SampleApp类的__init__方法中初始化。这样，您可以通过控制器（self.controller.frames[page_name]）访问帧

在本例中，我从一个类操作另一个类的元素。还有other options

import tkinter as tk                # python 3
from tkinter import font as tkfont
#from typing_extensions import IntVar  # python 3


class SampleApp(tk.Tk):
    # same
    ...


class StartPage(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        
        # TypeError is thrown for self.some_input.get() if the value entered is not a number
        # see: https://stackoverflow.com/questions/4140437/interactively-validating-entry-widget-content-in-tkinter
        # https://anzeljg.github.io/rin2/book2/2405/docs/tkinter/entry-validation.html
        self.some_input = tk.IntVar()
        # set the default to 1
        self.some_input.set(1)
        self.some_entry = tk.Entry(self, width=8, textvariable=self.some_input)
        self.some_entry.pack()
        # button to open the next page with certain conditions
        button1 = tk.Button(self, text='Next Page', command=self.show_next_frame)
        button1.pack()

    def show_next_frame(self):
        if self.some_input.get() == 0:
            pass
        else:
            # create labels in the PageOne class using the entered value
            self.controller.frames["PageOne"].create_labels(self.some_input.get())
            # reset the default to 1
            self.some_input.set(1)
            # show the prepared page
            self.controller.show_frame("PageOne")


class PageOne(tk.Frame):   

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller
        
        self.labels_finanziatori = {
        'principale': [],
        'capitale_investito': [], 
        'tasso': [], 
        'tempo': []
        }
        dict_finanziatori = {
        'numero': [],
        'capitale_investito': [], 
        'tasso': [], 
        'tempo': [],
        }
        Finanziatore_Semplice = []

    def create_labels(self, some_input):
        k = 0

        for i in range(0, some_input): 
            # create new labels
            label = tk.Label(self, text="Dati finanziatore numero "+str(i+1) +":\n")
            label.grid(row=i*(k+1), column = 0)
            # you can save labels if needed
            self.labels_finanziatori['principale'].append(label)
            k = k+1
        # button on the side of the labels
        button = tk.Button(self, text="Go to the start page",
                           command=lambda: self.controller.show_frame("StartPage")).grid(row=0, column=1)


if __name__ == "__main__":
    app = SampleApp()
    app.mainloop()