03-middleware

Middleware Example

This example demonstrates how to use and create custom middleware in Fox.

Features

• Built-in middleware (Logger, ResponseTime, Recovery)
• Custom authentication middleware
• Custom rate limiting middleware
• Request ID middleware
• Route-specific middleware
• Middleware groups

Running

go run main.go

Testing

Public Routes

# Home page
curl http://localhost:8080/

# Health check
curl http://localhost:8080/health

Protected Routes (Require Authentication)

# Without token (should fail)
curl http://localhost:8080/api/profile

# With invalid token (should fail)
curl -H "Authorization: Bearer invalid-token" \
  http://localhost:8080/api/profile

# With valid token (should succeed)
curl -H "Authorization: Bearer valid-token" \
  http://localhost:8080/api/profile

# Get data with valid token
curl -H "Authorization: Bearer valid-token" \
  http://localhost:8080/api/data

Rate Limited Routes

# First request (should succeed)
curl http://localhost:8080/limited/resource

# Immediate second request (should fail with 429)
curl http://localhost:8080/limited/resource

# Wait 1 second and try again (should succeed)
sleep 1
curl http://localhost:8080/limited/resource

Route-Specific Middleware

curl http://localhost:8080/special

Logger Middleware

curl http://localhost:8080/with-logger

Middleware Execution Order

1. Global middleware execute first (in order of Use())
2. Group middleware execute next
3. Route-specific middleware execute last
4. Handler executes
5. Middleware post-processing (in reverse order)

Request → Logger → ResponseTime → RequestID → Recovery →
         → [Group Auth] → [Route Specific] → Handler

Creating Custom Middleware

func MyMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        // Before request
        start := time.Now()

        // Process request
        c.Next()

        // After request
        duration := time.Since(start)
        fmt.Printf("Request took %v\n", duration)
    }
}

// Use it
router.Use(MyMiddleware())

Aborting Request

func AuthMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        if !isAuthorized(c) {
            c.AbortWithStatusJSON(401, gin.H{"error": "unauthorized"})
            return
        }
        c.Next()
    }
}

Built-in Middleware

Fox provides these built-in middleware:

• fox.Logger(): Request logging with TraceID
• fox.NewXResponseTimer(): Response time tracking
• gin.Recovery(): Panic recovery (from Gin)