devtools

python-devtools (pip install devtools) provides a number of tools which are useful during Python development, including debug() an alternative to print() which formats output in a way which should be easier to read than print as well as giving information about which file/line the print statement is on and what value was printed.

Pydantic integrates with devtools by implementing the __pretty__ method on most public classes.

In particular debug() is useful when inspecting models:

from datetime import datetime

from devtools import debug

from pydantic import BaseModel


class Address(BaseModel):
    street: str
    country: str
    lat: float
    lng: float


class User(BaseModel):
    id: int
    name: str
    signup_ts: datetime
    friends: list[int]
    address: Address


user = User(
    id='123',
    name='John Doe',
    signup_ts='2019-06-01 12:22',
    friends=[1234, 4567, 7890],
    address=dict(street='Testing', country='uk', lat=51.5, lng=0),
)
debug(user)
print('\nshould be much easier read than:\n')
print('user:', user)

Will output in your terminal:

{}

debug() is a development-time tool: it prints to the terminal of a process you're watching. The closest equivalent for a deployed application is Logfire, where models and validations show up as structured output you can browse and query.