[英]Pydantic add field to model after a model validation (add filed to incoming model)
[英]How do add an assembled field to a Pydantic model
假设我有 model
class UserDB(BaseModel):
first_name: Optional[str] = None
last_name: Optional[str] = None
我如何制作另一个 model,它是从这个构建的,并且有一个字段根据这个 model 中的字段而变化?
例如,像这样的东西
class User(BaseModel):
full_name: str = first_name + ' ' + last_name
像这样构造也许
User.parse_obj(UserDB)
谢谢!
如果您不想在User
中保留first_name
和last_name
,那么您可以
__init__
。full_name
。两种方法都可以满足您的要求:
from typing import Optional
from pydantic import BaseModel, validator
class UserDB(BaseModel):
first_name: Optional[str] = None
last_name: Optional[str] = None
class User_1(BaseModel):
location: str # for a change
full_name: Optional[str] = None
def __init__(self, user_db: UserDB, **data):
super().__init__(full_name=f"{user_db.first_name} {user_db.last_name}", **data)
user_db = UserDB(first_name="John", last_name="Stark")
user = User_1(user_db, location="Mars")
print(user)
class User_2(BaseModel):
first_name: Optional[str] = None
last_name: Optional[str] = None
full_name: Optional[str] = None
@validator('full_name', always=True)
def ab(cls, v, values) -> str:
return f"{values['first_name']} {values['last_name']}"
user = User_2(**user_db.dict())
print(user)
output
location='Mars' full_name='John Stark'
first_name='John' last_name='Stark' full_name='John Stark'
更新:对于使用response_model
,您可以通过以下方式自定义__init__
:
class User_1(BaseModel):
location: str # for a change
full_name: Optional[str] = None
# def __init__(self, user_db: UserDB, **data):
def __init__(self, first_name, last_name, **data):
super().__init__(full_name=f"{first_name} {last_name}", **data)
user_db = UserDB(first_name="John", last_name="Stark")
user = User_1(**user_db.dict(), location="Mars")
print(user)
我创建了一个 pip package 似乎完全可以满足您的需求。 这是链接: https://pypi.org/project/pydantic-computed/
您的示例将如下所示:
from pydantic import BaseModel
from pydantic_computed import Computed, computed
class UserDB(BaseModel):
first_name: Optional[str] = None
last_name: Optional[str] = None
class User(UserDB):
full_name: Computed[str]
@computed('full_name')
def compute_full_name(first_name: str, last_name: str):
return first_name + ' ' + last_name
# parsing also works as normal:
user_db = UserDB(first_name='John', last_name='Doe')
user = User.parse_obj(user_db)
print(user.full_name) # Outputs "John Doe"
这也适用于 response_model(例如在 FastAPI 中),因为计算值实际上是在 full_name 属性上设置的。
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