Updating instances

In this section we’ll see how to update existing instances using DTOData.

PUT handlers

PUT requests are characterized by requiring the full data model to be submitted for update.

from __future__ import annotations

from dataclasses import dataclass

from litestar import Litestar, put
from litestar.dto import DataclassDTO, DTOConfig, DTOData
from litestar.params import FromPath


@dataclass
class Person:
    name: str
    age: int
    email: str
    id: int


class ReadDTO(DataclassDTO[Person]):
    config = DTOConfig(exclude={"email"})


class WriteDTO(DataclassDTO[Person]):
    config = DTOConfig(exclude={"id"})


@put("/person/{person_id:int}", dto=WriteDTO, return_dto=ReadDTO, sync_to_thread=False)
def update_person(person_id: FromPath[int], data: DTOData[Person]) -> Person:
    # Usually the Person would be retrieved from a database
    person = Person(id=person_id, name="John", age=50, email="email_of_john@example.com")
    return data.update_instance(person)


app = Litestar(route_handlers=[update_person])

This script defines a PUT handler with path /person/{person_id:int} that includes a route parameter, person_id to specify which person should be updated.

In the handler, we create an instance of Person, simulating a database lookup, and then pass it to the DTOData.update_instance() method, which returns the same instance after modifying it with the submitted data.

PATCH handlers

PATCH requests are characterized by allowing any subset of the properties of the data model to be submitted for update. This is in contrast to PUT requests, which require the entire data model to be submitted.

from __future__ import annotations

from dataclasses import dataclass

from litestar import Litestar, patch
from litestar.dto import DataclassDTO, DTOConfig, DTOData
from litestar.params import FromPath


@dataclass
class Person:
    name: str
    age: int
    email: str
    id: int


class ReadDTO(DataclassDTO[Person]):
    config = DTOConfig(exclude={"email"})


class PatchDTO(DataclassDTO[Person]):
    config = DTOConfig(exclude={"id"}, partial=True)


@patch("/person/{person_id:int}", dto=PatchDTO, return_dto=ReadDTO, sync_to_thread=False)
def update_person(person_id: FromPath[int], data: DTOData[Person]) -> Person:
    # Usually the Person would be retrieved from a database
    person = Person(id=person_id, name="John", age=50, email="email_of_john@example.com")
    return data.update_instance(person)


app = Litestar(route_handlers=[update_person])

In this latest update, the handler has been changed to a @patch() handler.

This script introduces the PatchDTO class that has a similar configuration to WriteDTO, with the id field excluded, but it also sets partial=True. This setting allows for partial updates of the resource.

And here’s a demonstration of use: