尝试调用函数提交到 MySQL 时如何修复“未定义变量”

Posted 2023-02-24

【中文标题】尝试调用函数提交到 MySQL 时如何修复“未定义变量”

【英文标题】：How to fix ' variable not defined' when trying to call a function to submit to MySQL

【发布时间】：2019-08-31 03:23:27

【问题描述】：

我是 Tkinter 的新手，并试图创建一个函数来连接到我的 GUI 中的“提交”按钮，以便它将数据输入到我的 mysql 数据库中。反馈告诉我'itemCode_entry' is not defined 在def inv_submit(): 函数中。我正在尝试从def inv_menu(): 函数中获取来自itemCode_entry 的输入，并将其输入到MySQL 语句中的def inv_submit():。

这是我得到的反馈。

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Users\darre\AppData\Local\Programs\Python\Python37\lib\tkinter\__init__.py", line 1702, in __call__
    return self.func(*args)
  File "Import_Test_Code2.py", line 103, in <lambda>
    submit_btn = Button(btm_frame, text='Submit', bg=color1, command= lambda : inv_submit())
  File "Import_Test_Code2.py", line 207, in inv_submit
    item = itemCode_entry.get()
NameError: name 'itemCode_entry' is not defined

from tkinter import *
import mysql.connector

#  ======================MySQL Connection================================================================

mydb = mysql.connector.connect(
    host = "localhost",
    user = "root",
    passwd = "....",
    database = "testdb",
    )

# Create Cursor Instance
my_cursor = mydb.cursor()

# Create Database
#my_cursor.execute("CREATE DATABASE trialProjectdb")

root = Tk()
root.geometry('500x500')
root.title('Database Control')


color1 = 'grey77'
color2 = 'grey88'

item = int()
brandName = StringVar()
#unitsPer = int()
units = int()
cost = float()

#  ======================Frames================================================================

top_frame = Frame(root, width=500, height=80, bg=color1)
top_frame.pack(side=TOP)

btm_frame = Frame(root, width=500, height=500, bg=color2)
btm_frame.pack(side=TOP)


#  ======================Inventory=============================================================
inv_btn = Button(top_frame, text='Inventory', width=20,
             command= lambda : inv_menu())
inv_btn.place(x=0, y=0)

#  ======================Functions=============================================================

def inv_menu():

        menu_label = Label(btm_frame, text='Inventory', font=('arial', 12, 'bold'), bg=color2)
    menu_label.place(x=200, y=10)

    line = Label(btm_frame, text='______________________________________________________'
                            '________________________________________________', bg=color2)
    line.place(x=0, y=30)

    itemCode_label = Label(btm_frame, text='Item Code:', bg=color2)
    itemCode_label.place(x=22, y=60)

    itemCode_entry = Entry(btm_frame, textvariable=item)
    itemCode_entry.place(x=90, y=60)

    brand_label = Label(btm_frame, text='Brand:', bg=color2)
    brand_label.place(x=45, y=90)

    brand_entry = Entry(btm_frame, textvariable=brandName)
    brand_entry.place(x=90, y=90)

    units_label = Label(btm_frame, text='Units Per:', bg=color2)
    units_label.place(x=28, y=120)

    units_entry = Entry(btm_frame, textvariable=units)
    units_entry.place(x=90, y=120)

    unitCost_label = Label(btm_frame, text='Unit Cost:', bg=color2)
    unitCost_label.place(x=28, y=150)

    unitCost_entry = Entry(btm_frame, textvariable=cost)
    unitCost_entry.place(x=90, y=150)

    submit_btn = Button(btm_frame, text='Submit', bg=color1, command= lambda : inv_submit())
    submit_btn.place(x=90, y=180)


def inv_submit():


    item = itemCode_entry.get()
    brandName = brand_entry.get()
    units = units_entry.get()
    cost = unitCost_entry.get()


    my_cursor.execute("CREATE TABLE IF NOT EXIST 'trialprojectdb'.'Inventory' (Item_Code INTEGER AUTO_INCREMENT PRIMARY KEY , Brand VARCHAR(255), Units INTEGER(10), In_Stock INTEGER, Unit_Cost FLOAT(12,2)")

    my_cursor.execute("INSERT INTO Inventory (itemCode, brand, unitsPer, unitCost) VALUES(%s,%s,%s,%s)", (item, brandName, units, cost))

    mydb.commit()

    conn.close()



root.mainloop()

一旦我填写了“库存”表单inv_menu() 中的信息，我希望“提交”按钮submit_btn 将数据提交到MySQL 以更新数据库。

【问题讨论】：

itemCode 到底应该是什么？ itemCode_entry = Entry(btm_frame, textvariable=itemCode) "itemCode" 没有在任何地方定义

@alex067 抱歉。我尝试了很多方法来修复它，以至于我输入了错误的代码。我刚刚对代码和输出进行了编辑。谢谢。

What are the rules for local and global variables in Python?

【参考方案1】：

使其成为全局条目小部件：

global itemCode_entry
itemCode_entry = Entry(btm_frame, textvariable=item)
itemCode_entry.place(x=90, y=60)

【参考方案2】：

您遇到的问题是范围界定。例如，item = itemCode_entry.get() 在您的 inv_submit() 函数中。这将导致一个问题，因为在“inv_submit()”函数的范围内或程序的全局范围内都找不到“itemCode_entry.get()”。

一个可能的解决方案是这样的：

来自

dev inv_menu():
...
return itemCode_entry, brand_entry, units_entry, unitCost_entry

在你的

dev inv_submit():
item, brandName, units, cost = inv_menu()