如何在python中制作删除元素的按钮

Question

我正在用Python制作一个简单的任务管理器，但我想不出一种方法可以让按钮删除任务（如果制作完成）。

我尝试制作一个删除项目的功能，但没有成功。由于某种原因，该函数仅删除第一项，然后开始给出错误：

ValueError：list.remove（x）：x不在列表中

import json
from tkinter import *

PATH = "data.json"


class Data:
    data: list[dict] = []

    def __init__(self):
        self.read_data()

    def read_data(self):
        with open(PATH, "r") as file:
            self.data = json.load(file)

    def write_data(self):
        with open(PATH, "w") as file:
            json.dump(self.data, file, indent=4)

    def update_ids(self):
        id = 0
        for task in self.data:
            task['id'] = id
            id += 1
        self.write_data()

    def write_task(self, name: str, date: str, importance: str):
        self.data.append({
            "name": name,
            "date": date,
            "importance": importance,
            "id": self.data[-1]['id'] + 1
        })
        self.write_data()

    def get_task(self, id: int) -> dict:
        for task in self.data:
            if task['id'] == id:
                return task

    def __iter__(self):
        for task in self.data:
            yield task

    def delete_task(self, id: int):
        self.data = [task for task in self.data if task['id'] != id]
        self.write_data()


Tasks = Data()


class Window(Tk):
    tasks: list[dict] = []

    def __init__(self):
        super().__init__()
        self.protocol("WM_DELETE_WINDOW", self.on_closing)

        self.create_tasks()
        self.render_tasks()
        self.mainloop()

    def create_tasks(self):
        for task in Tasks:
            label = Label(self, text=f"task :{task['name']} \ndate : {task['date']}", fg=task['importance'])
            button = Button(self, text="Delete")

            pack = {
                "label": label,
                "button": button
            }
            self.tasks.append(pack)

            def function():
                label.destroy()
                button.destroy()
                self.tasks.remove(pack)
                Tasks.delete_task(task['id'])
                self.render_tasks()

            button.config(command=function)

    def render_tasks(self):
        for task in self.tasks:
            task['label'].pack()
            task['button'].pack()

    def on_closing(self):
        Tasks.update_ids()
        self.destroy()


if __name__ == "__main__":
    wnd = Window()

Answer 1

您遇到的问题是如何定义 function() 。您在其中所做的就是引用局部变量（标签、按钮、包……），这些变量在您执行循环时会被修改。循环完成后，这些变量保留最后一次迭代的值，这就是为什么您总是在第一次按时删除最后一个（无论按哪个按钮），而第二次则失败。

您可以做的是为所有这些值找到一些外部存储，以便您可以在删除时引用它们，并使用部分定义每个按钮的命令，以便每个按钮都有它所引用的条目的标识（如此处所解释）。

我对你的程序做了一个非常粗略的修改来展示这个想法。至少您会看到正确的项目从窗口中消失，尽管它缺少数据中的删除：

import json
from tkinter import *
from functools import partial

PATH = "data.json"


class Data:
    data: list[dict] = []

    def __init__(self):
        self.read_data()

    def read_data(self):
        with open(PATH, "r") as file:
            self.data = json.load(file)

    def write_data(self):
        with open(PATH, "w") as file:
            json.dump(self.data, file, indent=4)

    def update_ids(self):
        id = 0
        for task in self.data:
            task['id'] = id
            id += 1
        self.write_data()

    def write_task(self, name: str, date: str, importance: str):
        self.data.append({
            "name": name,
            "date": date,
            "importance": importance,
            "id": self.data[-1]['id'] + 1
        })
        self.write_data()

    def get_task(self, id: int) -> dict:
        for task in self.data:
            if task['id'] == id:
                return task

    def __iter__(self):
        for task in self.data:
            yield task

    def delete_task(self, id: int):
        self.data = [task for task in self.data if task['id'] != id]
        self.write_data()


Tasks = Data()

class Window(Tk):
    tasks: dict[dict] = {}
    
    def __init__(self):
        super().__init__()
        self.protocol("WM_DELETE_WINDOW", self.on_closing)

        self.create_tasks()
        self.render_tasks()
        self.mainloop()

    def create_tasks(self):
        for task in Tasks:
            label_text = f"task :{task['name']} \ndate : {task['date']}"
            label = Label(self, text=label_text, fg=task['importance'])
            button = Button(self, text="Delete")

            pack = {
                "label": label,
                "button": button
            }
            
            self.tasks[label_text]=pack

            def function(t):
                print(t)
                print(self.tasks[t])
                self.tasks[t]['label'].destroy()
                self.tasks[t]['button'].destroy()
                #Tasks.delete_task(self.tasks[t]['id'])
                self.tasks.pop(t)
                self.render_tasks()

            button.config(command=partial(function, label_text))

    def render_tasks(self):
        for task in self.tasks.values():
            print(task)
            task['label'].pack()
            task['button'].pack()

    def on_closing(self):
        Tasks.update_ids()
        self.destroy()


if __name__ == "__main__":
    wnd = Window()