API Star ✨🚀✨🌟

A smart Web API framework, designed for Python 3.

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Install API Star:

$ pip3 install apistar

Create a new project:

$ apistar new --template minimal
app.py
tests.py
$ cat app.py
from apistar import App, Route

def welcome():
    return {'message': 'Welcome to API Star!'}

app = App(routes=[
    Route('/', 'GET', welcome)
])

Run the application:

$ apistar run
Running at http://localhost:8080/

Run the tests:

$ apistar test
tests.py ..
===== 2 passed in 0.05 seconds =====

---

Requests

API Star allows you to dynamically inject various information about the incoming request into your views using type annotation.

from apistar import http

def show_request(request: http.Request):
    return {
        'method': request.method,
        'url': request.url,
        'headers': dict(request.headers)
    }

def show_query_params(query_params: http.QueryParams):
    return {
        'params': dict(query_params)
    }

def show_user_agent(user_agent: http.Header):
    return {
        'user-agent': user_agent
    }

Some of the components you might use most often:

Component	Description
Request	The HTTP request. Includes .method, .url, and .headers attributes.
Headers	The request headers, returned as a dictionary-like object.
Header	Lookup a single request header, corresponding to the argument name. Returns a string or None.
QueryParams	The request query parameters, returned as a dictionary-like object.
QueryParam	Lookup a single query parameter, corresponding to the argument name. Returns a string or None.
Body	The request body. Returns a bytestring.

---

Responses

By default API star expects view to return plain data, and will return 200 OK responses.

def create_project():
    return {'name': 'new project', 'id': 123}

You can instead set the status code or headers by annotating the view as returning a Response.

def create_project() -> Response:
    data = {'name': 'new project', 'id': 123}
    headers = {'Location', 'http://example.com/project/123/'}
    return Response(data, status=201, headers=headers)

---

URL Routing

Use {curly_braces} in your URL conf to include a URL path parameter.

def echo_username(username):
    return {'message': f'Welcome, {username}!'}

app = App(routes=[
    Route('/{username}/', 'GET', echo_username)
])

Use type annotation on the view method to include typed URL path parameters.

users = {0: 'penny', 1: 'benny', 2: 'jenny'}

def echo_username(user_id: int):
    username = users[user_id]
    return {'message': f'Welcome, {username}!'}

app = App(routes=[
    Route('/{user_id}/', 'GET', echo_username)
])

Parameters which do not correspond to a URL path parameter will be treated as query parameters.

def echo_username(username):
    if username is None:
        return {'message': 'Welcome!'}
    return {'message': f'Welcome, {username}!'}

app = App(routes=[
    Route('/hello/', 'GET', echo_username)
])

---

WSGI

Because API views are so dynamic, they'll even let you drop right down to returning a WSGI response directly:

from apistar import wsgi

def hello_world() -> wsgi.WSGIResponse:
    wsgi.WSGIResponse(
        '200 OK',
        [('Content-Type', 'text/plain')],
        [b'Hello, world!']
    )

You can also inject the WSGI environment into your view arguments:

def debug_environ(environ: wsgi.WSGIEnviron):
    return {
        'environ': environ
    }

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Testing

API Star includes the py.test testing framework. You can run all tests in a tests.py module or a tests/ directory, by using the following command:

$ apistar test

The simplest way to test a view is to call it directly.

from app import hello_world

def test_hello_world():
    assert hello_world() == {"hello": "world"}

There is also a test client, that allows you to make HTTP requests directly to your application, using the requests library.

from apistar.test import TestClient

def test_hello_world():
    client = TestClient()
    response = client.get('/hello_world/')
    assert response.status_code == 200
    assert response.json() == {"hello": "world"}

Requests made using the test client may use either relative URLs, or absolute URLs. In either case, all requests will be directed at your application, rather than making external requests.

response = client.get('http://www.example.com/hello_world/')

---

Components

You can create new components to inject into your views, by declaring a class with a build method. For instance:

import base64

class Username(str):
    """
    A component which returns the username that the incoming request
    is associated with, using HTTP Basic Authentication.
    """
    @classmethod
    def build(cls, authorization: http.Header):
        if authorization is None:
            return None
        scheme, token = authorization.split()
        if scheme.lower() != 'basic':
            return None
        username, password = base64.b64decode(token).decode('utf-8').split(':')
        return cls(username)

You can then use your component in a view:

def say_hello(username: Username):
    return {'hello': username}

A complete listing of the available built-in components:

Component	Description
app.App	The application instance.
http.Method	The HTTP method of the request, such as GET.
http.Host	The host component of the request URL, such as 'example.com'.
http.Port	The port number that the request is made to, such as 443.
http.Scheme	The scheme component of the request URL, such as 'https'.
http.Path	The path component of the request URL, such as /api/v1/my_view/.
http.QueryString	The query component of the request URL, such as page=2.
http.URL	The full URL of the request, such as https://example.com/api/v1/my_view/?page=2.
http.Body	The body of the request, as a bytestring.
http.QueryParams	A multi-dict containing the request query parameters.
http.QueryParam	A single request query parameter, corresponding to the keyword argument name. Automatically used for data arguments.
http.Headers	A multi-dict containing the request headers parameters.
http.Header	A single request query parameter, corresponding to the keyword argument name.
http.Request	The full request instance.
http.Response	A return type for returning an HTTP response explicitly.
http.ResponseData	A return type for plain data responses.
wsgi.Environ	The WSGI environ of the incoming request.
wsgi.Response	A return type for directly returning a WSGI response.
routing.URLPathArgs	A dictionary containing all the matched URL path arguments.
routing.URLPathArg	A single URL path argument, corresponding to the keyword argument name. Automatically used for data arguments with a matching URL path component.
pipelines.ArgName	The keyword argument with which a component is being injected into the view. May be used within component build methods.

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Performance

The following results were obtained on a 2013 MacBook Air, using the simplest "JSON Serialization" TechEmpower benchmark.

Framework	Configuration	Requests/sec	Avg Latency
API Star	gunicorn + meinheld	25,195	7.94ms
Sanic	uvloop	21,233	10.19ms
Falcon	gunicorn + meinheld	16,692	12.08ms
Flask	gunicorn + meinheld	5,238	38.28ms

A pull request has been issued to add API Star to future rounds of the TechEmpower benchmarks. In the future we plan to be adding more realistic & useful test types, such as database query performance.

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Deployment

A development server is available, using the run command:

$ apistar run

The recommended production deployment is GUnicorn, using the Meinheld worker.

$ pip install gunicorn
$ pip install meinheld
$ gunicorn app:app.wsgi --workers=4 --bind=0.0.0.0:5000 --pid=pid --worker-class=meinheld.gmeinheld.MeinheldWorker

Typically you'll want to run as many workers as you have CPU cores on the server.

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Development

To work on the API Star codebase, you'll want to clone the repository, and create a Python virtualenv with the project requirements installed:

$ git clone [email protected]:tomchristie/apistar.git
$ cd apistar
$ ./scripts/setup

To run the continuous integration tests and code linting:

$ ./scripts/test
$ ./scripts/lint

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API Star is BSD licensed code.
Designed & built in Brighton, England.
— ⭐️ —