Python，在按钮组合框中获取值时出现问题

Question

我试图用一个按钮获取当前组合框的值并显示消息。 但是我做了一些错误的事情来正确的选择值。在

AttributeError: 'SelectDB' object has no attribute 'cmb'

如何获取combobox值？在

^{pr2}$

Answer 1

试试看，我做了些改变

import sqlite3
from tkinter import *
from tkinter import ttk
from tkinter import messagebox

class SelectDB:
    def __init__(self, wind) :
        self.wind = wind
        self.wind.title ('MyApp')
        ttk.Label(self.wind, text="Select you're Database:").grid (row = 0, column = 0)
        self.cbCombo = ttk.Combobox(self.wind, width="10", values=("Local (sqllite)","MYSQL"))
        self.cbCombo.grid (row = 0, column = 1)
        ttk.Button(text="Start", command=self.checkcmbo).grid (row = 1, column = 0)

    def checkcmbo(self):

        if self.cbCombo.current()!=-1:
            if self.cbCombo.current() ==0:
                msg="You choos sqlite"
            else:
                msg="You choos MYSQL"

            messagebox.showwarning('MyApp',msg,)
        else:
            messagebox.showwarning('MyApp','You must choose something!',)

if __name__ == '__main__':
    wind = Tk()
    application = SelectDB(wind)
    wind.mainloop()

Answer 2

Entry对象和所有其他小部件的grid、pack和place函数返回None。在python中，当您执行a（）.b（）时，表达式的结果是b（）返回的任何结果，因此Entry（…）.grid（…）将不返回任何结果。在

你应该把它分成两行

    self.cmb = ttk.Combobox(self.wind, width="10", values=("Local (sqllite)","MYSQL"))
    self.cmb.grid (row = 0, column = 1)

class SelectDB:
def __init__(self, wind) :
    self.wind = wind
    self.wind.title ('MyApp')

    ttk.Label(self.wind, text="Select you're Database:").grid (row = 0, column = 0)

    self.cmb = ttk.Combobox(self.wind, width="10", values=("Local (sqllite)","MYSQL"))
    self.cmb.grid (row = 0, column = 1)
    btn = ttk.Button(text="Start", command=self.checkcmbo).grid (row = 1, column = 0)

def checkcmbo(self):
    if self.cmb.get() == "Local (sqllite)":
        messagebox.showinfo("What user choose", "you choose Local (sqllite)")
    elif self.cmb.get() == "MYSQL":
        messagebox.showinfo("What user choose", "you choose MYSQL")
    else:
        messagebox.showinfo("What user choose", "NOTHING")

  if __name__ == '__main__':
      wind = Tk()
      application = SelectDB(wind)
      wind.mainloop()