Python搁置不保存嵌套键

如何解决Python搁置不保存嵌套键

我正在使用 saveSign = () => { this.ref.current.saveImage(); } 模块来保存一些 Python 对象（示例中的字符串）。

当我尝试将对象保存为嵌套键时，它没有被保存。

shelve

代码应该打印：

class Car:
    def __init__(self,ID):
        self.id = ID

    def save_to_shelf(self):
        with shelve.open('shelf') as shelf:
           if not shelf.get('users'):
                shelf['users'] = {}

            print(shelf['users'])
            try:
                shelf['users'][self.id] = "hello"
            except Exception as e:
                print(e)
            print('saved')
            print(shelf['users'])

car = Car(123)
car.save_to_shelf()

但它会打印：

{}
saved
{123: hello}

意思是它没有被保存

如果我打印键的值，它会给出 {} saved {}

KeyError

错误

shelf['users'][self.id] = "hello"
print(shelf['users'][self.id])

如果我在保存时执行以下操作，我可以保存它 而不是

Traceback (most recent call last):
  File "P:/Python practice/Shelll/main.py",line 3,in <module>
    car.save_to_shelf()
  File "P:/Python practice/Shelll\db.py",line 20,in save_to_shelf
    print(shelf['users'][self.id])
KeyError: '123'

这有效

with shelve.open('shelf') as shelf:
    shelf['users'][self.id] = "hello"

我想了解这背后的原因。据我所知， with shelve.open('shelf') as shelf: USERS = shelf['users'] USERS[self.id] = self.id shelf['users'] = USERS # or this works # with shelve.open('shelf') as shelf: # shelf['users'] = {self.id:"hello"} 对象用作字典。所以我之前保存的方式应该有效，但没有。