[英]How to use values from list to validate some calculations in pydantic BaseModel?
[英]How to use values from list as pydantic validator?
我想創建 pydantic model 來驗證用戶表單。 我的 model 值之一應從名稱列表中進行驗證。 我使用枚舉成功創建了 model,如下所示:
from enum import Enum
class Fruit(str, Enum):
APPLE = 'apple'
BANANA = 'banana'
MELON = 'melon'
from pydantic import BaseModel
class UserForm(BaseModel):
fruit: Fruit
name: str
現在我想將枚舉切換到我的代碼中的值列表:
fruit = ['apple','banana','melon']
我怎樣才能做到這一點?
tnx
您可以通過以下方式使用validator
:
from pydantic import BaseModel, ValidationError, validator
class UserForm(BaseModel):
fruit: str
name: str
@validator('fruit')
def fruit_must_be_in_fruits(cls,fruit):
fruits=['apple','banana','melon']
if fruit not in fruits:
raise ValueError(f'must be in {fruits}')
return fruit
try:
UserForm(fruit="apple",name="apple")
except ValidationError as e:
print(e)
如果不符合條件,它將引發驗證錯誤。
您也可以通過Literal
類型列表來執行此操作。 像這樣:
import pydantic
from typing import Literal, List
class M(pydantic.BaseModel):
fruits: List[Literal["apple", "orange"]]
print(M.parse_obj({"fruits":["apple", "orange"]})) # OK fruits=['apple', 'orange']
print(M.parse_obj({"fruits":["apple", "orange", "potato"]})) # Error unexpected value potato
您可以通過其.__members__
字典獲取有關枚舉的信息 - 在這里您可以簡單地迭代它的鍵:
from enum import Enum
class Fruit(str, Enum):
APPLE = 'apple'
BANANA = 'banana'
MELON = 'melon'
# only need __members__ if you need more infos about it
print(Fruit.__members__)
# you do not need the __members__ if you just want the keys
print([name.lower() for name in Fruit])
Output:
# enums __members__ dictionary
{'APPLE': <Fruit.APPLE: 'apple'>,
'BANANA': <Fruit.BANANA: 'banana'>,
'MELON': <Fruit.MELON: 'melon'>}
# lower keys
['apple', 'banana', 'melon']
我提出了一個優雅的解決方案。
from pydantic import BaseModel
from typing import List
from enum import Enum
class Fruit(str, Enum):
APPLE = 'apple'
BANANA = 'banana'
MELON = 'melon'
class UserForm(BaseModel):
fruits: List[Fruit]
name: str
就是這樣。
檢查上面的代碼:
將上面的代碼放在文件main.py
中。
跑
python -i main.py
>>> uf = UserForm(fruits=['apple','banana'],name='hello')
>>> uf
UserForm(fruits=[<Fruit.APPLE: 'apple'>, <Fruit.BANANA: 'banana'>], name='hello')
>>> af = UserForm(fruits=['monkey','apple'],name='hello')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pydantic/main.py", line 400, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 1 validation error for UserForm
fruits -> 0
value is not a valid enumeration member; permitted: 'apple', 'banana', 'melon' (type=type_error.enum; enum_values=[<Fruit.APPLE: 'apple'>, <Fruit.BANANA: 'banana'>, <Fruit.MELON: 'melon'>])
>>>
pydantic 會引發錯誤,因為monkey
不在水果中。
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