spacs 0.0.8

Simple Pydantic AIOHTTP Client Sessions

SPACS: Simple Pydantic AIOHTTP Client Sessions

A package to assist in managing and using long-lived AIOHTTP client sessions with simplicity. Built to handle Pydantic objects.

Features

• Handles request params and bodies as either Pydantic objects or native Python dictionaries, converting items to JSON-safe format.
• Abstracts away internals of managing the request/response objects, instead either returning parsed response content on success, or raising a specialized error object.
• Automatically manages persistent connections to be shared over extended lifespan across application, cleaning up all open connections on teardown.
• Utilizes modern Python type hinting.

Installation

Using poetry (preferred):

poetry add spacs

Using pip:

pip install spacs

Basic Usage

SPACS currently supports the HTTP methods GET, POST, PUT, and DELETE. All methods take the same, singular SpacsRequest argument. The following are some common patterns to be utilized when working with SPACS.

Request With Params

import asyncio
from spacs import SpacsClient, SpacsRequest

async def example():
    client = SpacsClient(base_url="https://httpbin.org")
    request = SpacsRequest(path="/get", params={"foo": "bar"})
    result = await client.get(request)
    print(result)
    await client.close()


loop = asyncio.new_event_loop()
loop.run_until_complete(example())

Sending Pydantic objects via request body

import asyncio
from spacs import SpacsClient, SpacsRequest
from pydantic import BaseModel

class Person(BaseModel):
    name: str
    age: int

async def example():
    client = SpacsClient(base_url="https://httpbin.org")
    person = Person(name="James", age=25)
    request = SpacsRequest(path="/post", body=person)
    response = await client.post(request)
    print(response)
    await client.close()


loop = asyncio.new_event_loop()
loop.run_until_complete(example())

Tip: Response Model

For all examples here, if the API declares that response bodies will only contain json data representing a Pydantic object, the payload can be deserialized into an object by specifying a Pydantic class in the request. For example, using our above Person model:

request = SpacsRequest(path="/post", body=person, response_model=Person)
response = await client.post(request)
assert isinstance(response, Person)

Handling Errors

Manual Error Handling

import asyncio
from spacs import SpacsClient, SpacsRequest, SpacsRequestError

async def example():
    client = SpacsClient(base_url="https://httpbin.org")
    request = SpacsRequest(path="/status/404")
    try:
        await client.get(request)
    except SpacsRequestError as error:
        print({"code": error.status, "reason": error.reason})
    await client.close()


loop = asyncio.new_event_loop()
loop.run_until_complete(example())

Injecting Error Handler

import asyncio
from spacs import SpacsClient, SpacsRequest, SpacsRequestError

async def error_handler(error: SpacsRequestError) -> None:
    print(f"It blew up: {error.reason}")

async def example():
    client = SpacsClient(base_url="https://httpbin.org", error_handler=error_handler)
    request = SpacsRequest(path="/status/504")
    response = await client.get(request)
    await client.close()
    assert response is None


loop = asyncio.new_event_loop()
loop.run_until_complete(example())

Closing sessions

In the above examples, a client.close() call is made. This is to ensure that the underlying AIOHTTP session is properly cleaned up, and is a step that should always be performed on application teardown. Alternatively, the following can be used to close all open sessions without having to directly reference a client instance:

await SpacsClient.close_all()

SPACS is not affiliated with httpbin.org.

Building

poetry build