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Overview

The slash middleware handles trailing slashes in URLs by adding or removing them with redirects. Use it for URL consistency and SEO.

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Installation

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

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Quick Start

app := mizu.New()

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

// Remove trailing slash: /about/ → /about
app.Use(slash.Remove())

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Functions

FunctionDescription
Add()Add trailing slash (301 redirect)
AddCode(code)Add with custom status code
Remove()Remove trailing slash (301 redirect)
RemoveCode(code)Remove with custom status code

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Examples

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Add Trailing Slash

app.Use(slash.Add())
// /about    → 301 → /about/
// /contact  → 301 → /contact/
// /about/   → (no redirect)
// /         → (no redirect)

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Remove Trailing Slash

app.Use(slash.Remove())
// /about/   → 301 → /about
// /contact/ → 301 → /contact
// /about    → (no redirect)
// /         → (no redirect)

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Temporary Redirect

app.Use(slash.AddCode(302))     // Temporary redirect
app.Use(slash.RemoveCode(307))  // Preserve HTTP method

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Behavior

  • Root path / is never modified
  • Query strings are preserved
  • Uses 301 (Permanent) by default

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Technical Details

The slash middleware implements trailing slash normalization through HTTP redirects. It provides four main functions that return middleware handlers:

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Implementation

  • Add(): Wraps AddCode() with HTTP 301 (Moved Permanently) status
  • AddCode(code int): Returns middleware that checks if path lacks trailing slash and redirects to add it
  • Remove(): Wraps RemoveCode() with HTTP 301 (Moved Permanently) status
  • RemoveCode(code int): Returns middleware that checks if path has trailing slash and redirects to remove it

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Internal Logic

  1. Path Extraction: Reads the request URL path from c.Request().URL.Path
  2. Root Protection: Always skips the root path / to prevent infinite redirects
  3. Slash Detection: Uses strings.HasSuffix(path, "/") to check for trailing slash
  4. Target Construction: Builds redirect URL by adding/removing trailing slash
  5. Query Preservation: Appends ? + c.Request().URL.RawQuery if query string exists
  6. Redirect Execution: Calls c.Redirect(code, target) with specified status code
  7. Pass-through: Calls next(c) if no redirect needed

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Performance Characteristics

  • Zero allocations for paths that don’t need redirection
  • Single string concatenation for building redirect target
  • Early exit for root path and paths already in correct format
  • No regular expressions - uses simple string operations

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Best Practices

  • Choose one style and be consistent
  • Use 301 for permanent SEO benefit
  • Apply early in middleware chain

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Testing

The slash middleware includes comprehensive test coverage for all functions and edge cases:
Test CaseDescriptionExpected Behavior
Add - adds trailing slashRequest to /test with Add() middlewareRedirects to /test/ with 301 status
Add - preserves queryRequest to /test?foo=bar with Add() middlewareRedirects to /test/?foo=bar preserving query string
Add - skips rootRequest to / with Add() middlewareReturns 200 OK, no redirect performed
AddCode - custom statusRequest to /test with AddCode(307) middlewareRedirects to /test/ with 307 status
Remove - removes trailing slashRequest to /test/ with Remove() middlewareRedirects to /test with 301 status
Remove - preserves queryRequest to /test/?foo=bar with Remove() middlewareRedirects to /test?foo=bar preserving query string
Remove - skips rootRequest to / with Remove() middlewareReturns 200 OK, no redirect performed
RemoveCode - custom statusRequest to /test/ with RemoveCode(302) middlewareRedirects to /test with 302 status