Redirect

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Overview

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Installation

import "github.com/go-mizu/mizu/middlewares/redirect"

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Quick Start

app := mizu.New()

// Redirect HTTP to HTTPS
app.Use(redirect.HTTPSRedirect())

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Functions

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Examples

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HTTPS Redirect

// Permanent redirect to HTTPS
app.Use(redirect.HTTPSRedirect())

// Temporary redirect (307)
app.Use(redirect.HTTPSRedirectCode(307))

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WWW Handling

// Add www prefix
app.Use(redirect.WWWRedirect())

// Remove www prefix
app.Use(redirect.NonWWWRedirect())

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Trailing Slash

// Add trailing slash: /about → /about/
app.Use(redirect.TrailingSlashRedirect())

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Custom Redirect Rules

app.Use(redirect.New([]redirect.Rule{
    {From: "/old-page", To: "/new-page", Code: 301},
    {From: "/blog", To: "/articles", Code: 302},
}))

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Regex Redirects

app.Use(redirect.New([]redirect.Rule{
    {
        From:  `^/posts/(\d+)$`,
        To:    "/articles/$1",
        Regex: true,
        Code:  301,
    },
}))

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Combined Redirects

app.Use(redirect.HTTPSRedirect())
app.Use(redirect.NonWWWRedirect())

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API Reference

func HTTPSRedirect() mizu.Middleware
func HTTPSRedirectCode(code int) mizu.Middleware
func WWWRedirect() mizu.Middleware
func WWWRedirectCode(code int) mizu.Middleware
func NonWWWRedirect() mizu.Middleware
func NonWWWRedirectCode(code int) mizu.Middleware
func TrailingSlashRedirect() mizu.Middleware
func TrailingSlashRedirectCode(code int) mizu.Middleware
func New(rules []Rule) mizu.Middleware

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Rule Type

type Rule struct {
    From  string  // Source path or regex
    To    string  // Target URL ($1, $2 for captures)
    Code  int     // HTTP status code (default: 301)
    Regex bool    // Is From a regex pattern?
}

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Status Codes

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Technical Details

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Implementation Overview

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HTTPS Redirect

• Checks if the request is non-HTTPS by examining c.Request().TLS and the X-Forwarded-Proto header
• Constructs the HTTPS URL using the request’s host and request URI
• Returns redirect response with the specified status code (default: 301)

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WWW Domain Redirect

• WWWRedirect: Checks if the host lacks the “www.” prefix and adds it
• NonWWWRedirect: Checks if the host has the “www.” prefix and removes it
• Preserves the original protocol (HTTP/HTTPS) by checking TLS and X-Forwarded-Proto
• Constructs the redirect URL with the modified host

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Trailing Slash Redirect

• Examines the request path to see if it lacks a trailing slash
• Skips the root path (”/”) to avoid unnecessary redirects
• Preserves query strings when redirecting
• Adds ”/” suffix to the path before redirecting

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Custom Rule-Based Redirect

• Compiles regex patterns at initialization time for performance
• Sets default status code (301) if not specified
• For each request, iterates through rules in order:
  • Regex rules: Uses FindStringSubmatch to capture groups, replaces $0, $1, $2, etc. in the target URL
  • Exact match rules: Performs simple string comparison on the path
• Preserves query strings by appending RawQuery to the target URL
• Returns the first matching rule’s redirect

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Performance Considerations

• Regex patterns are compiled once during middleware initialization, not on each request
• Rules are evaluated in order; place more frequently matched rules first
• HTTPS and WWW redirects perform minimal string operations
• Query string preservation adds negligible overhead

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Best Practices

1. Order Matters: Apply HTTPS redirect before WWW/non-WWW redirects
2. Status Codes: Use 301 for permanent SEO-friendly redirects, 307/308 to preserve HTTP methods
3. Regex Efficiency: Keep regex patterns simple; complex patterns impact performance
4. Rule Organization: Place frequently matched rules at the beginning of the rules array
5. Testing: Always test redirects with query strings and various HTTP methods

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Testing

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Related Middlewares

• slash - Trailing slash handling
• rewrite - URL rewriting (no redirect)
• secure - HTTPS with security headers