A Dispatcher extension for Sanic which also acts as a Sanic-to-WSGI adapter
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README.md

Sanic-Dispatcher

A Dispatcher extension for Sanic that also acts as a Sanic-to-WSGI adapter

Allows you to do this: (seriously)

from sanic import Sanic, response
from sanic_dispatcher import SanicDispatcherMiddlewareController
from flask import Flask, make_response, current_app as flask_app

app = Sanic(__name__)

dispatcher = SanicDispatcherMiddlewareController(app)

child_sanic_app = Sanic("MyChildSanicApp")

child_flask_app = Flask("MyChildFlaskApp")

@app.middleware("response")
async def modify_response(request, response):
    response.body = response.body + b"\nModified by Sanic Response middleware!"
    response.headers['Content-Length'] = len(response.body)
    return response

@app.route("/")
async def index(request):
    return response.text("Hello World from {}".format(request.app.name))

@child_sanic_app.route("/")
async def index(request):
    return response.text("Hello World from {}".format(request.app.name))

@child_flask_app.route("/")
def index():
    app = flask_app
    return make_response("Hello World from {}".format(app.import_name))

dispatcher.register_sanic_application(child_sanic_app, '/sanicchild', apply_middleware=True)
dispatcher.register_wsgi_application(child_flask_app.wsgi_app, '/flaskchild', apply_middleware=True)

if __name__ == "__main__":
    app.run(port=8001, debug=True)

Installation

pip install Sanic-Dispatcher

How To Use

First make a Sanic application the way you normally do:

from sanic import Sanic

app = Sanic(__name__) # This creates a sanic app

app becomes your 'base' or 'parent' sanic app which will accommodate the Dispatcher extension

Create a Dispatcher

from sanic_dispatcher import SanicDispatcherMiddlewareController

dispatcher = SanicDispatcherMiddlewareController(app)

dispatcher is your new dispatcher controller. Note: This takes a reference to app as its first parameter, but it does not consume app, nor does it return app.

I want to dispatch another Sanic App

app = Sanic(__name__)

dispatcher = SanicDispatcherMiddlewareController(app)

otherapp = Sanic("MyChildApp")

dispatcher.register_sanic_application(otherapp, "/childprefix")

@otherapp.route('/')
async def index(request):
    return response.text("Hello World from Child App")

Browsing to url /childprefix/ will invoke the otherapp App, and call the / route which displays "Hello World from Child App"

What if the other App is a Flask App?

from flask import Flask, make_response

app = Sanic(__name__)

dispatcher = SanicDispatcherMiddlewareController(app)
flaskapp = Flask("MyFlaskApp")

# register the wsgi_app method from the flask app into the dispatcher
dispatcher.register_wsgi_application(flaskapp.wsgi_app, "/flaskprefix")

@flaskapp.route('/')
def index():
    return make_response("Hello World from Flask App")

Browsing to url /flaskprefix/ will invoke the Flask App, and call the / route which displays "Hello World from Flask App"

What if the other App is a Django App?

import my_django_app

app = Sanic(__name__)

dispatcher = SanicDispatcherMiddlewareController(app)
# register the django wsgi application into the dispatcher
dispatcher.register_wsgi_application(my_django_app.wsgi.application,
                                     "/djangoprefix")

Browsing to url /djangoprefix/ will invoke the Django App.

Can I run a default application?

The Sanic App app you create at the start is also the default app.

When you navigate to a URL that does not match a registered dispatch prefix, this Sanic app will handle the request itself as per normal.

app = Sanic(__name__)

dispatcher = SanicDispatcherMiddlewareController(app)

otherapp = Sanic("MyChildApp")

dispatcher.register_sanic_application(otherapp, "/childprefix")

@app.route('/')
async def index(request):
    return response.text("Hello World from Default App")

@otherapp.route('/')
async def index(request):
    return response.text("Hello World from Child App")

Browsing to url / will not invoke any Dispatcher applications, so app will handle the request itself, resolving the / route which displays "Hello World from Default App"

I want to apply common middleware to the registered applications!

Easy!

import my_django_app
from flask import Flask, make_response, current_app

app = Sanic(__name__)

dispatcher = SanicDispatcherMiddlewareController(app)

child_sanic_app = Sanic("MyChildSanicApp")

child_flask_app = Flask("MyChildFlaskApp")

@app.middleware("request")
async def modify_request(request):
    request.headers['Content-Type'] = "text/plain"

@app.middleware("response")
async def modify_response(request, response):
    response.body = response.body + b"\nModified by Sanic Response middleware!"
    response.headers['Content-Length'] = len(response.body)
    return response

@app.route("/")
async def index(request):
    return response.text("Hello World from {}".format(request.app.name))

@child_sanic_app.route("/")
async def index(request):
    return response.text("Hello World from {}".format(request.app.name))

@child_flask_app.route("/")
def index():
    app = current_app
    return make_response("Hello World from {}".format(app.import_name))

dispatcher.register_sanic_application(child_sanic_app,
                                      '/childprefix', apply_middleware=True)
dispatcher.register_wsgi_application(my_django_app.wsgi.application,
                                     '/djangoprefix', apply_middleware=True)
dispatcher.register_wsgi_application(child_flask_app.wsgi_app,
                                     '/flaskprefix', apply_middleware=True)

The key here is passing apply_middleware=True to the relevant register application function. By default apply_middleware is set to False for all registered dispatcher applications.

In this example the Sanic Request Middleware modify_request will be applied to ALL requests, including those handled by applications registered on the dispatcher. The request middleware will be applied to the request before it is passed to any registered applications.

In this example the Sanic Response Middleware modify_response will be applied to ALL responses, including those which were generated by applications registered on the dispatcher. The response middleware will be applied to the response after it is processed by the registered application.