ShahriyarR

from pydantic import BaseModel

class DBCredentialsModel(BaseModel):
    comment: str
    password: Password
    uri: DBUri
    port: DBPort
    host: DBHost

    class Config:

ShahriyarR

import json

class CustomDBCredentialsEncoder(json.JSONEncoder):
    def default(self, obj):
        try:
            # Intentionally omit other fields
            return {"uri": obj.uri.get_secret()}
        except AttributeError:
            return super().default(obj)
            

ShahriyarR

@dataclass
class DBCredentials:
    password: Password
    uri: DBUri
    port: DBPort
    host: DBHost

ShahriyarR

>>> print(credentials)
DBCredentialsWithDescriptors(password=ReadOnce[secrets=*****], uri=ReadOnce[secrets=*****], port=ReadOnce[secrets=*****], host=ReadOnce[secrets=*****])

ShahriyarR

>>> credentials = DBCredentialsWithDescriptors()
>>> credentials.password.get_secret()
'db-password'

>>> credentials.password.get_secret()
...
readonce.UnsupportedOperationException: ('Not allowed on sensitive value', 'Sensitive data was already consumed')

ShahriyarR

@dataclass
class DBCredentialsWithDescriptors:
    password: Password = Password("db-password")
    uri: DBUri = DBUri("mysql://")
    port: DBPort = DBPort(3306)
    host: DBHost = DBHost("localhost")

ShahriyarR

from readonce import ReadOnce

class Password(ReadOnce):
    def __init__(self, password: str) -> None:
        super().__init__()
        self.add_secret(password)


class DBUri(ReadOnce):
    def __init__(self, uri: str) -> None:

ShahriyarR

DBPassword(password="awesome")
...
AttributeError: 'DBPassword' object has no attribute 'password'

ShahriyarR

from readonce import ReadOnce
from dataclasses import dataclass

@dataclass
class DBPassword(ReadOnce):
    password: str
    def __post_init__(self):
        # This is going to fail with "AttributeError: 'DBPassword' object has no attribute 'password'"
        self.add_secret(self.password)

ShahriyarR

>>> obj = Password(password="awesome_password")
>>> print(obj)
ReadOnce[secrets=*****]
>>> obj
ReadOnce[secrets=*****]