| """ |
| Application Dispatcher |
| ====================== |
| |
| This middleware creates a single WSGI application that dispatches to |
| multiple other WSGI applications mounted at different URL paths. |
| |
| A common example is writing a Single Page Application, where you have a |
| backend API and a frontend written in JavaScript that does the routing |
| in the browser rather than requesting different pages from the server. |
| The frontend is a single HTML and JS file that should be served for any |
| path besides "/api". |
| |
| This example dispatches to an API app under "/api", an admin app |
| under "/admin", and an app that serves frontend files for all other |
| requests:: |
| |
| app = DispatcherMiddleware(serve_frontend, { |
| '/api': api_app, |
| '/admin': admin_app, |
| }) |
| |
| In production, you might instead handle this at the HTTP server level, |
| serving files or proxying to application servers based on location. The |
| API and admin apps would each be deployed with a separate WSGI server, |
| and the static files would be served directly by the HTTP server. |
| |
| .. autoclass:: DispatcherMiddleware |
| |
| :copyright: 2007 Pallets |
| :license: BSD-3-Clause |
| """ |
| import typing as t |
|
|
| if t.TYPE_CHECKING: |
| from _typeshed.wsgi import StartResponse |
| from _typeshed.wsgi import WSGIApplication |
| from _typeshed.wsgi import WSGIEnvironment |
|
|
|
|
| class DispatcherMiddleware: |
| """Combine multiple applications as a single WSGI application. |
| Requests are dispatched to an application based on the path it is |
| mounted under. |
| |
| :param app: The WSGI application to dispatch to if the request |
| doesn't match a mounted path. |
| :param mounts: Maps path prefixes to applications for dispatching. |
| """ |
|
|
| def __init__( |
| self, |
| app: "WSGIApplication", |
| mounts: t.Optional[t.Dict[str, "WSGIApplication"]] = None, |
| ) -> None: |
| self.app = app |
| self.mounts = mounts or {} |
|
|
| def __call__( |
| self, environ: "WSGIEnvironment", start_response: "StartResponse" |
| ) -> t.Iterable[bytes]: |
| script = environ.get("PATH_INFO", "") |
| path_info = "" |
|
|
| while "/" in script: |
| if script in self.mounts: |
| app = self.mounts[script] |
| break |
|
|
| script, last_item = script.rsplit("/", 1) |
| path_info = f"/{last_item}{path_info}" |
| else: |
| app = self.mounts.get(script, self.app) |
|
|
| original_script_name = environ.get("SCRIPT_NAME", "") |
| environ["SCRIPT_NAME"] = original_script_name + script |
| environ["PATH_INFO"] = path_info |
| return app(environ, start_response) |
|
|
