如何使自定义数据类可订阅？

Question

考虑从

pydantic

包派生的数据类：

from typing import List
from pydantic import BaseModel 


class Bucket(BaseModel):
    setting: List[str]
    fight_1: List[int]
    cause_1: List[str]

让

my_bucket

成为

Bucket

的实例：

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']                                                                                                         

然后回来

['some_value']

，但我得到的是：

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

TypeError: 'Bucket' object is not subscriptable

Answer 1

带 pydantic

您可以将您的属性作为 pydantic 中的属性进行访问。

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

如果想使用

[]

来访问，需要定义

__getitem__

:

from typing import List
from pydantic import BaseModel


class Bucket(BaseModel):
    setting: List[str]
    fight_1: List[int]
    cause_1: List[str]

    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'])  # ['some_value']

无 pydantic

如果您不想使用

pydantic

并创建自定义数据类，您可以这样做：

from dataclasses import dataclass


@dataclass
class CustomDataClass:
    data: int

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


obj = CustomDataClass(42)
print(obj.data)  # 42
print(obj["data"])  # 42, needs __getitem__ to be implemented

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}