How would you implement middleware in Go using the standard library pattern vs a framework?

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Accepted Answer

// Standard library middleware
type Middleware func(http.Handler) http.Handler

// Logging middleware
func Logger(logger *slog.Logger) Middleware {
    return func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            start := time.Now()
            rw := &responseWriter{ResponseWriter: w, code: 200}
            next.ServeHTTP(rw, r)
            logger.Info("request",
                slog.String("method", r.Method),
                slog.String("path", r.URL.Path),
                slog.Int("status", rw.code),
                slog.Duration("duration", time.Since(start)),
            )
        })
    }
}

// Auth middleware
func RequireAuth(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        token := r.Header.Get("Authorization")
        if !validateToken(token) {
            http.Error(w, "unauthorized", http.StatusUnauthorized)
            return
        }
        next.ServeHTTP(w, r)
    })
}

// Chain middleware
func Chain(h http.Handler, middlewares ...Middleware) http.Handler {
    for i := len(middlewares) - 1; i >= 0; i-- {
        h = middlewares[i](h)
    }
    return h
}

// Usage
handler := Chain(
    mux,
    Logger(logger),
    RequireAuth,
    RateLimiter(100),
) Standard library: no dependencies, explicit, full control — preferred for simple services Gin: Use() method chains middleware; request context via gin.Context; fast router with params Echo: similar to Gin, cleaner API, built-in binder and validator Chi: 100% compatible with net/http; lightweight router with middleware support For most APIs: net/http + Chi or stdlib routing (Go 1.22) is sufficient without a full framework

How would you implement middleware in Go using the standard library pattern vs a framework?

Middleware in Go is a function that wraps an http.Handler and returns a new http.Handler. This pattern is the same whether using the standard library or frameworks like Gin and Echo.

How would you implement middleware in Go using the standard library pattern vs a framework?

Middleware in Go is a function that wraps an http.Handler and returns a new http.Handler. This pattern is the same whether using the standard library or frameworks like Gin and Echo.

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