Python DTO

Data Transfer Objects (DTO) with Python.

Install

pip install py_dto

Requires Python 3.9 or newer. Tested on Python 3.9 through 3.14.

Usage

Define the object properties with types defined, then pass a dict with data.

Basic example

For type hinting

from py_dto import DTO

# This DTO will be used as a type definition
class UserProfile(DTO):
    avatar: str

# The DTO with the properties defined
class User(DTO):
    profile: UserProfile
    name: str
    email: str
    age: int
    tags: list[str]

# Create the DTO instance
user = User({
    'profile': UserProfile({'avatar': 'https://i.pravatar.cc/300'}),
    'name': 'John',
    'email': 'john@example.com',
    'age': 42,
    'tags': ['developer', 'python']
})

print(user.name) # 'John'
print(user.profile.avatar) # https://i.pravatar.cc/300

The Any type

Even DTO are supposed to specify data types, you can use the Any type to accept literally any type for a property:

from py_dto import DTO
from typing import Any

# The DTO accepts "any" type of data for the "name" property
class User(DTO):
    name: Any

# Create the DTO instance
user = User({
    'name': 'John',
})

print(user.name) # 'John'

user = User({
    'name': 123,
})

print(user.name) # 123

Dealing with None

Imagine you are retrieving data from a database table where a column is empty for some records.

By using python's Optional type on a specific property, the DTO will not raise an exception if a None value is set.

from py_dto import DTO
from typing import Optional

# The DTO "name" property can be a str or a None value
class User(DTO):
    name: Optional[str]

# Create the DTO instance with a "str"
user = User({
    'name': 'John',
})

print(user.name) # 'John'

# Create the DTO instance with a "None"
user = User({
    'name': None,
})

print(user.name) # None

# Any other type will raise an exception
try:
    user = User({
        'name': 123,
    })
except:
    print('123 does not have a "str" nor a "None" type')

License

This project is open-sourced software licensed under the MIT license.

Original idea comes from spatie/data-transfer-object package for PHP.