如何使自定义数据 class 可订阅

Question

考虑从 pydantic 包导出的此数据 class：

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

有 pydantic

您可以访问您的属性作为 pydantic 中的一个属性。

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

如果要使用[]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']

没有花里胡哨的

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}

如何使自定义数据 class 可订阅

How to make custom data class subscriptable

python-3.x

pydantic

有 pydantic

没有花里胡哨的