https://github.com/adriangb/xpresso

A composable Python ASGI web framework
https://github.com/adriangb/xpresso

api async backend json openapi pydantic python starlette swagger-ui web

Last synced: 14 days ago
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A composable Python ASGI web framework

• Host: GitHub
• URL: https://github.com/adriangb/xpresso
• Owner: adriangb
• License: mit
• Created: 2022-01-17T23:15:32.000Z (almost 3 years ago)
• Default Branch: main
• Last Pushed: 2023-03-18T22:28:49.000Z (over 1 year ago)
• Last Synced: 2024-10-18T12:19:34.620Z (26 days ago)
• Topics: api, async, backend, json, openapi, pydantic, python, starlette, swagger-ui, web
• Language: Python
• Homepage: https://xpresso-api.dev/
• Size: 6.46 MB
• Stars: 178
• Watchers: 5
• Forks: 4
• Open Issues: 16
• Metadata Files:
  • Readme: README.md
  • Contributing: CONTRIBUTING.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE.txt

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README

        


  







    





    





    





    





Xpresso is an ASGI web framework built on top of [Starlette], [Pydantic] and [di], with heavy inspiration from [FastAPI].

Some of the standout features are:

- ASGI support for high performance (within the context of Python web frameworks)

- OpenAPI documentation generation

- Automatic parsing and validation of request bodies and parameters, with hooks for custom extractors

- Full support for [OpenAPI parameter serialization](https://swagger.io/docs/specification/serialization/)

- Highly typed and tested codebase with great IDE support

- A powerful dependency injection system, backed by [di]

## Requirements

Python 3.7+

## Installation

```shell

pip install xpresso

```

You'll also want to install an ASGI server, such as [Uvicorn].

```shell

pip install uvicorn

```

## Example

Create a file named `example.py`:

```python

from pydantic import BaseModel

from xpresso import App, Path, FromPath, FromQuery

class Item(BaseModel):

    item_id: int

    name: str

async def read_item(item_id: FromPath[int], name: FromQuery[str]) -> Item:

    return Item(item_id=item_id, name=name)

app = App(

    routes=[

        Path(

            "/items/{item_id}",

            get=read_item,

        )

    ]

)

```

Run the application:

```shell

uvicorn example:app

```

Navigate to [http://127.0.0.1:8000/items/123?name=foobarbaz](http://127.0.0.1:8000/items/123?name=foobarbaz) in your browser.

You will get the following JSON response:

```json

{"item_id":123,"name":"foobarbaz"}

```

Now navigate to [http://127.0.0.1:8000/docs](http://127.0.0.1:8000/docs) to poke around the interactive [Swagger UI] documentation:

![Swagger UI](docs/readme_example_swagger.png)

For more examples, tutorials and reference materials, see our [documentation].

## Inspiration and relationship to other frameworks

Xpresso is mainly inspired by FastAPI.

FastAPI pioneered several ideas that are core to Xpresso's approach:

- Leverage Pydantic for JSON parsing, validation and schema generation.

- Leverage Starlette for routing and other low level web framework functionality.

- Provide a simple but powerful dependency injection system.

- Use that dependency injection system to provide extraction of request bodies, forms, query parameters, etc.

Xpresso takes these ideas and refines them by:

- Decoupling the dependency injection system from the request/response cycle, leading to an overall much more flexible and powerful dependency injection system, packaged up as the standalone [di] library.

- Decoupling the framework from Pydantic by using `Annotated` ([PEP 593]) instead of default values (`param: FromQuery[str]` instead of `param: str = Query(...)`).

- [Middleware on Routers] so that you can use generic ASGI middleware in a routing-aware manner (for example, installing profiling middleware on only some paths without using regex matching).

- Support for [lifespans on any Router or mounted App] (this silently fails in FastAPI and Starlette)

- [dependency injection into the application lifespan] and support for [multiple dependency scopes].

- Formalizing the framework for extracting parameters and bodies from requests into the [Binder API] so that 3rd party extensions can do anything the framework does.

- Support for [customizing parameter and form serialization].

- Better performance by implementing [dependency resolution in Rust], [executing dependencies concurrently] and [controlling threading of sync dependencies on a per-dependency basis].

### Inspiration **to** FastAPI

When I originally concieved Xpresso I wasn't sure what the goal was. I didn't necessarily want to replace FastAPI, I know how much work open source is and was not and am not willing to commit to something like that. So I always thought of the project more as a testing ground for interesting ideas for ASGI web frameworks in general and FastAPI in particular.

I am happy to report that in this sense it has been a _smash hit_. In the time since writing the above differences:

- Starlette added support for middleware on routers.

- The ASGI spec, Starlette and FastAPI added support for returning data from lifespans, which I think may be an even better idea than dependency scopes.

- FastAPI added support for PEP593 annotations, taking direct inspiration from Xpresso's approach.

- I've established a strong working relationship with Sebastián, FastAPI's author, and I foresee more ideas from Xpresso leaking into FastAPI in some way or another.

So where does that leave Xpresso? It's going to stay around, but it's less likely to become a stable production ready framework: it can provide more value to the community as an exprimental proving ground for ideas than as yet another "production ready" web framework.

[Starlette]: https://github.com/encode/starlette

[Pydantic]: https://github.com/samuelcolvin/pydantic/

[FastAPI]: https://github.com/adriangb/xpresso

[di]: https://github.com/adriangb/di

[Uvicorn]: http://www.uvicorn.org/

[documentation]: https://www.xpresso-api.dev/

[Swagger UI]: https://swagger.io/tools/swagger-ui/

[dependency injection into the application lifespan]: https://xpresso-api.dev/latest/tutorial/lifespan

[multiple dependency scopes]: https://xpresso-api.dev/latest/tutorial/dependencies/scopes/

[dependency resolution in Rust]: https://github.com/adriangb/graphlib2

[executing dependencies concurrently]: https://xpresso-api.dev/latest/advanced/dependencies/performance/#concurrent-execution

[controlling threading of sync dependencies on a per-dependency basis]: https://xpresso-api.dev/latest/advanced/dependencies/performance/#sync-vs-async

[PEP 593]: https://www.python.org/dev/peps/pep-0593/

[Binder API]: https://xpresso-api.dev/latest/advanced/binders/

[customizing parameter and form serialization]: https://xpresso-api.dev/latest/tutorial/query_params/#customizing-deserialization

[lifespans on any Router or mounted App]: https://xpresso-api.dev/latest/tutorial/lifespan/

[Middleware on Routers]: https://xpresso-api.dev/0.14.1/tutorial/middleware/#middleware-on-routers