Ina ka rubuta ingantacciyar tabbatarwa a Pydantic?

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Accepted Answer

Bayan ƙayyadaddun hantsi, Pydantic yana ba ka damar rubuta **ingantacciyar hanyoyin tabbatarwa** tare da field validators (tabbatawa fili daya) da model validators (tabbatawa a cikin filaye masu yawa) — ga ƙa'idoji waɗanda ƙayyadaddun hantsi ba za su iya bayyana ba. (Tsarin da aka nuna shine Pydantic v2.)

## Field validators — tabbatawa/canza fili daya

```python
from pydantic import BaseModel, field_validator

class User(BaseModel):
    username: str
    password: str

@field_validator("username")
    @classmethod
    def username_alphanumeric(cls, v: str) -> str:
        if not v.isalnum():
            raise ValueError("username must be alphanumeric")   # → a 422 error
        return v.lower()                                         # can also TRANSFORM the value
```

A `@field_validator` yana aiwatar da ingantacciyar hanya a fili: ɗaga `ValueError` don kaddaci abin da bai gamasu ba (FastAPI yana canzar shi zuwa sanin 422), ko kuma kada darajar da aka canza (misali, daidaita zuwa ƙananan haruffa).

## Model validators — tabbatawa a cikin filaye da yawa

```python
from pydantic import model_validator

class SignupForm(BaseModel):
    password: str
    confirm_password: str

@model_validator(mode="after")
    def passwords_match(self):
        if self.password != self.confirm_password:    # compare MULTIPLE fields
            raise ValueError("passwords do not match")
        return self
```

A `@model_validator(mode="after")` yana aiwatar bayan jiya filaye duka an tabbata su, tare da damar zuwan gidanmu masu rikon — ana amfani da shi ga ƙa'idoji da suka ƙunshi **filaye masu yawa** (misali, tabbatawa cewa kalmar sirri ta dace, ko cewa kwanan farko ya isa wajen ƙarshe).

## Tabbatarwa da aka sauni sau da yawa ya cika da farko

```python
class Product(BaseModel):
    price: float = Field(gt=0)          # use Field constraints for simple rules
    sku: str = Field(pattern=r"^[A-Z]{3}-\d+$")
    email: EmailStr                      # specialized types for formats
# reach for custom validators only when constraints/types can't express the rule
```

Ga `Field` hantsi da nau'ikan da aka keɓe don ƙa'idoji masu sauƙi; amfani da ingantacciyar validators ga ainihin hanya ta kasua.

## Me ya sa hakan ya matuhu

Ingantacciyar Pydantic tabbatarwa ita ce mahimmanci don jera ƙa'idoji na kasua waɗanda suka wuce waje da ƙa'idoji masu faɗi da hantsi — kuma tun da tabbatarwa ita ce mahimmanci ga **tsaro da ingantacciyar data**, samun damar bayyana duk wata ƙa'ida ita ce mahimmanci. **Field validators** suna shawo da ƙa'idoji na fili daya (tabbatarwa na ingantacciyar tsarin, yada/canzawa), yayin da **model validators** suna shawo da buɗun ga **tabbatarwa a cikin filaye da yawa** (kalma sirri da suka dace, jeri na lokaci, buƙatun da suka dogara) waɗanda ƙa'idoji na matsayin fili ba za su iya bayyana ba.

Validators suna haɗa jiya da FastAPI — `ValueError` da aka ɗaga yana zama sanin 422 jiya kaina.

Jiyadar lokacin da za a yi amfani da hantsi/nau'ikan da aka sauni (ga ƙa'idoji masu sauƙi) kuɗi da ingantacciyar validators (ga ainihin hanya ta kasua), da kuma yadda field vs model validators suka bambanta, yana ba ka damar tabbatawa cewa abin da ya zo ya cika duk buƙatun aikina na aikinka, na ya yi hakan mahimmanci ilimi ga gina tsofaffin, daidai APIs.