Cerasus
Cerasus is a simple dispatcher and quickstart function for ASGI apps based on Hypercorn with Request/Response objects from Starlette.
The dispatcher uses a mapping like this:
{
'GET': {
'': webapp.index,
'/': webapp.index,
'/items/get': webapp.api.items.get
},
'POST': {
'/items/add': webapp.api.items.add
}
}No REST. No Routes. What can be simpler?
The mapping is constructed by expose decorators. Here's an example that matches the mapping above:
from cerasus import expose, quickstart
from starlette.requests import Request
from starlette.responses import HTMLResponse, JSONResponse
class APIError(Exception):
def __init__(self, status_code, description):
self.status_code = status_code
self.description = description
class Items:
@expose
async def get(self, request):
items = []
# get items
# ...
return JSONResponse(dict(status='success', items=items))
@expose(methods='POST')
async def add(self, request):
item = await request.json()
# add item
# ...
return JSONResponse(dict(status='success'))
class Api:
# Customized error handling for API.
# Error handlers can be either coroutines that return Starlette Response objects, or just objects:
_undefined_method = JSONResponse(dict(status='error', description='Method not allowed'), status_code=405)
_undefined_handler = JSONResponse(dict(status='error', description='Bad endpoint'), status_code=404)
async def _exception_handler(self, request, exc):
return JSONResponse(dict(status='error', description=exc.description), status_code=exc.status_code)
# Note that children "inherit" error responses, i.e. we do not define them for Items
items = Items()
class Webapp:
api = Api()
@expose(name='/')
async def index(self, request):
return HTMLResponse('<h1>Hello</h1>')
async def open_db():
pass
async def close_db():
pass
if __name__ == "__main__":
quickstart(
Api(),
{
'bind': ['127.0.0.1:12345']
'alpn_protocols': ['h2']
},
base_urlpath = '/',
on_startup = open_db,
on_shutdown = close_db
)
