[Document] Order of middlewares

I just started a project with starlette awesome, and found a small issue about the docs related on the order of execution of middlewares… My case, is so usual, like in django:

auth_middleware that depends on session_middleware

Seems like the order is inverse on the order you declare them:

app.add_middleware(AuthenticationMiddleware, backend=middlewares.AuthBackend())
app.add_middleware(middlewares.SessionMiddleware)

The session one is executed first but needs to be added later. I’m not against it, it’s an onion, and can be seen in both directions… But I thought that at least should be documented.

On the API side, perhaps is a nice idea, to just instantiate them on a single call, like:

app.add_middlewares([
   middlewareX, middlewareY  # in order of execution... (at least when the request is entering..)
])

[invokermain]

had the same issue, just adding some documentation would be great as this is a pretty opaque bug to fix.

[aminalaee]

I think this was achieved in Version 0.13.0. From the current docs:

Every Starlette application automatically includes two pieces of middleware by default:

• ServerErrorMiddleware - Ensures that application exceptions may return a custom 500 page, or display an application traceback in DEBUG mode. This is always the outermost middleware layer.
• ExceptionMiddleware - Adds exception handlers, so that particular types of expected exception cases can be associated with handler functions. For example raising HTTPException(status_code=404) within an endpoint will end up rendering a custom 404 page.

Middleware is evaluated from top-to-bottom, so the flow of execution in our example application would look like this:

• Middleware
  • ServerErrorMiddleware
  • TrustedHostMiddleware
  • HTTPSRedirectMiddleware
  • ExceptionMiddleware
• Routing
• Endpoint

So this can be closed now.