Middleware

Middleware wraps the request/response cycle — it runs before a handler sees the request and after it produces a response. Use it for cross-cutting concerns: CORS, compression, security headers, logging.

Adding middleware

app.add_middleware() accepts middleware in two forms — a configured instance, or a class together with its keyword options:

from veloce import CORSMiddleware, Veloce

app = Veloce()

# Instance form — build the middleware, then add it.
app.add_middleware(
    CORSMiddleware(
        allow_origins=["*"],
        allow_methods=["GET", "POST", "PUT", "DELETE"],
    )
)

# Class form — pass the class and its options; Veloce constructs it.
app.add_middleware(CORSMiddleware, allow_origins=["*"])

Middleware can also be passed when constructing the app, via the middleware=[...] argument to Veloce(...).

Built-in middleware

Middleware	Purpose
CORSMiddleware	Cross-Origin Resource Sharing
GZipMiddleware	Response compression
CSRFMiddleware	Double-submit-cookie CSRF protection
SessionMiddleware	Signed, timestamped session cookies
TrustedHostMiddleware	Host-header allow-list
HTTPSRedirectMiddleware	Redirect plain HTTP to HTTPS
ProxyFix	Honour X-Forwarded-* from trusted proxies

All are importable from the top-level veloce package.

Function middleware

For one-off logic, register a function with @app.middleware("http"). It receives the request and a call_next callable that runs the rest of the stack:

@app.middleware("http")
async def add_timing_header(request, call_next):
    response = await call_next(request)
    response.headers["X-Powered-By"] = "veloce"
    return response

Class-based middleware

For reusable middleware, subclass BaseHTTPMiddleware and implement dispatch:

from veloce import BaseHTTPMiddleware


class RequestIDMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request, call_next):
        response = await call_next(request)
        response.headers["X-Request-ID"] = new_id()
        return response


app.add_middleware(RequestIDMiddleware())

Ordering

Middleware runs in the order it is added on the way in, and in reverse on the way out — the first one added is the outermost layer.