I am trying to do a validation on passwords where if they dont match, return an error. But I want to assign the error to field.
class RequestFile(
BaseModel
):
password: str = Field(..., min_length=8, max_length=128)
confirm_password: str = Field(..., min_length=8, max_length=128)
@field_validator("password")
def password_validate(cls, v: str) -> str:
if not v.strip():
raise ValueError("Password required")
return v
@field_validator("confirm_password")
def confirm_password_validate(cls, v: str) -> str:
if not v.strip():
raise ValueError("Confirm Password Required")
return v
@model_validator(mode="before")
def check_passwords_match(cls, values):
password = values.get("password")
confirm_password = values.get("confirm_password")
if password != confirm_password:
raise ValueError("Passwords does not match")
return values
In the code above, when either password or confirm_password failed validation (char length), it pushes the ValueError to field password and confirm_password respectively. However, when they dont match, it returns the ValueError but not on any field. How to push the ValueError to either password or confirm_password? Preferrably in confirm_password
There is an example in the official documentation.
To explain briefly, after-validators can access parsed fields via the info argument.
from pydantic import BaseModel, Field, field_validator
from pydantic_core.core_schema import ValidationInfo
class RequestFile(BaseModel):
password: str = Field(..., min_length=8, max_length=128)
confirm_password: str = Field(..., min_length=8, max_length=128)
@field_validator("password")
@classmethod
def password_validate(cls, v: str) -> str:
if not v.strip():
raise ValueError("Password required")
return v
@field_validator("confirm_password")
@classmethod
def confirm_password_validate(cls, v: str) -> str:
if not v.strip():
raise ValueError("Confirm Password Required")
return v
@field_validator("confirm_password", mode="after")
@classmethod
def check_passwords_match(cls, value: str, info: ValidationInfo) -> str:
if value != info.data["password"]:
raise ValueError("Passwords do not match")
return value
RequestFile(
password="password123",
confirm_password="password12",
)
pydantic_core._pydantic_core.ValidationError: 1 validation error for RequestFile
confirm_password
Value error, Passwords do not match [type=value_error, input_value='password12', input_type=str]
For further information visit https://errors.pydantic.dev/2.11/v/value_error