python-3.x - 如何使自定义数据类可下标

Question

考虑从“pydantic”包派生的这个数据类：

from typing import List
from pydantic import BaseModel 
class Bucket(BaseModel):
    setting: List[str]
    fight_1: List[int]
    cause_1: List[str]

让我们my_bucket成为一个实例Bucket：

my_bucket = Bucket(setting = ['some_value'], fight_1 = [0], cause_1 = ['other_value'])

基本上我希望能够做到

my_bucket['setting']                                                                                                         

并返回['some_value']，但我得到：

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-18-cacbdc1698e9> in <module>
----> 1 my_bucket['setting']

TypeError: 'Bucket' object is not subscriptable

Answer 1

由于您没有定义__init__方法，因此您无法Bucket使用参数实例化 a。所以这是无效的：

my_bucket = Bucket(setting = ['some_value'], fight_1 = [0], cause_1 = ['other_value'])

你可以这样做：

my_bucket = Bucket()
my_bucket.setting = ['some_value']
my_bucket.fight_1 = [0]
my_bucket.cause_1 = ['other_value']

为了达到settingwith my_bucket["setting"]，您需要__getitem__在您的类中定义方法：

class Bucket(BaseModel):
    ...
    def __getitem__(self, item):
        return getattr(self, item)

现在你可以做my_bucket["setting"]，它会返回：

['some_value']

编辑：我相信以下代码是您真正想要的：

from typing import List
from pydantic import BaseModel

class Bucket(BaseModel):
    def __init__(self, setting: List[str], fight_1: List[int],
                 cause_1: List[str]):
        self.setting = setting
        self.fight_1 = fight_1
        self.cause_1 = cause_1
        super().__init__()

    def __getitem__(self, item):
        return getattr(self, item)


my_bucket = Bucket(setting=['some_value'], fight_1=[0],
                   cause_1=['other_value'])

print(my_bucket['setting'])

Answer 2

对于 python 数据类，这对我有用：

from dataclasses import dataclass

@dataclass
class MyCustomRequest:
    request: Dict
        
    def __getitem__(self, key):
        return super().__getattribute__(key)

>>> a = MyCustomRequest({"a":10})
>>> a["request"]
{"a":10}
>>> a.request
{"a": 10}