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Sarj Code Standards

no-duplicate-field-validator-body

Pydantic field validators in one model repeat the same body.

SARJ496 Rule source Tests Catalog JSON

Why

Two field validators with the same mode and the same body are one validation rule written twice; a later fix to one copy silently leaves the other field validated by the old rule.

Fix

List every field in one @field_validator(...) decorator and branch on info.field_name where the fields genuinely differ.

Examples

Before — flagged Two validators repeat one strip rule
models/contact.py
from pydantic import BaseModel, field_validator




class Contact(BaseModel):
    first_name: str
    last_name: str


    @field_validator("first_name", mode="before")
    @classmethod
    def strip_first(cls, value: str) -> str:
        return value.strip()


    @field_validator("last_name", mode="before")
    @classmethod
    def strip_last(cls, raw: str) -> str:
        return raw.strip()
After — preferred One validator names every field that shares the rule
models/contact.py
from pydantic import BaseModel, field_validator




class Contact(BaseModel):
    first_name: str
    last_name: str


    @field_validator("first_name", "last_name", mode="before")
    @classmethod
    def strip_names(cls, value: str) -> str:
        return value.strip()