基于用户输入实现零售管理系统Combobox联动更新

原代码核心问题 #

• 联动逻辑仅在Combobox初始化时执行一次，未绑定用户选择事件，无法响应后续操作
• 控件变量作用域受限，回调函数无法访问dropdown内定义的Combobox
• 数据库操作后未关闭连接，存在资源泄漏
• 主窗口的invoice为局部变量，dropdown直接引用会导致报错

修正后的完整代码 #

import tkinter as tk
from tkinter import ttk
import sqlite3

def main_window():
    invoice = tk.Toplevel()
    # 绑定图片到窗口对象，避免被垃圾回收
    invoice.billimage1 = tk.PhotoImage(file="C:/Users/.../Documents/CODE/billimage.PNG")
    label2 = tk.Label(invoice, image=invoice.billimage1)
    label2.pack(fill="both", expand=True)
    return invoice

def dropdown(invoice):
    global combobox1, combobox2, combobox3

    conn = sqlite3.connect('store.db')
    c = conn.cursor()

    # 初始化品类选项
    c.execute("SELECT DISTINCT product_cat FROM raw_inventory")
    cat_list = [item[0] for item in c.fetchall()]

    # 初始化下拉框，子品类/产品初始为空
    combobox1 = ttk.Combobox(invoice, values=cat_list, width=60, font=('Arial', 14))
    combobox1.place(relx=0.035, rely=0.42)

    combobox2 = ttk.Combobox(invoice, values=[], width=60, font=('Arial', 14))
    combobox2.place(relx=0.035, rely=0.49)

    combobox3 = ttk.Combobox(invoice, values=[], width=60, font=('Arial', 14))
    combobox3.place(relx=0.035, rely=0.56)

    combobox4 = ttk.Combobox(invoice, values=[], width=60, font=('Arial', 14))
    combobox4.place(relx=0.035, rely=0.64)

    # 绑定选择事件
    combobox1.bind("<<ComboboxSelected>>", update_subcat)
    combobox2.bind("<<ComboboxSelected>>", update_product)

    conn.close()

def update_subcat(event):
    selected_cat = combobox1.get()
    if not selected_cat:
        combobox2.configure(values=[])
        combobox3.configure(values=[])
        return
    
    conn = sqlite3.connect('store.db')
    c = conn.cursor()
    c.execute("SELECT DISTINCT product_subcat FROM raw_inventory WHERE product_cat=?", (selected_cat,))
    subcat_list = [item[0] for item in c.fetchall()]
    combobox2.configure(values=subcat_list)
    combobox3.configure(values=[])  # 清空产品选项
    conn.close()

def update_product(event):
    selected_cat = combobox1.get()
    selected_subcat = combobox2.get()
    if not selected_cat or not selected_subcat:
        combobox3.configure(values=[])
        return
    
    conn = sqlite3.connect('store.db')
    c = conn.cursor()
    c.execute("SELECT product_name FROM raw_inventory WHERE product_cat=? AND product_subcat=?", 
              (selected_cat, selected_subcat))
    product_list = [item[0] for item in c.fetchall()]
    combobox3.configure(values=product_list)
    conn.close()

# 启动程序
root = tk.Tk()
root.withdraw()  # 隐藏默认主窗口
invoice_win = main_window()
dropdown(invoice_win)
root.mainloop()

关键改动说明 #

1. 事件绑定：通过<<ComboboxSelected>>事件，让用户选择时自动触发联动更新
2. 变量作用域：将Combobox设为全局变量，确保回调函数能访问并修改其选项
3. 动态查询：子品类和产品下拉框初始为空，仅在用户选择后从数据库查询对应数据，提升性能
4. 资源管理：每次数据库操作后关闭连接，避免资源泄漏
5. 图片引用修复：将图片绑定到窗口对象，防止被垃圾回收导致图片不显示

内容的提问来源于stack exchange，提问作者user21489407