Rewrite

Rewrite middleware rewrites the URL path based on the provided rules. It is helpful for backward compatibility or for creating cleaner and more descriptive links.

All core middleware lives in the middleware package:

import "github.com/labstack/echo/v5/middleware"

Usage

e.Pre(middleware.Rewrite(map[string]string{
  "/old":              "/new",
  "/api/*":            "/$1",
  "/js/*":             "/public/javascripts/$1",
  "/users/*/orders/*": "/user/$1/order/$2",
}))

The values captured in asterisks can be retrieved by index, e.g. $1, $2, and so on. Each asterisk is non-greedy (translated to a capture group (.*?)); when using multiple asterisks, a trailing * matches the rest of the path.

Caution

Rewrite middleware should be registered via Echo#Pre() so it runs before the router.

Custom configuration

e := echo.New()
e.Pre(middleware.RewriteWithConfig(middleware.RewriteConfig{}))

Configuration

type RewriteConfig struct {
  // Skipper defines a function to skip middleware.
  Skipper Skipper

  // Rules defines the URL path rewrite rules. The values captured in asterisk can be
  // retrieved by index e.g. $1, $2 and so on.
  // Example:
  // "/old":              "/new",
  // "/api/*":            "/$1",
  // "/js/*":             "/public/javascripts/$1",
  // "/users/*/orders/*": "/user/$1/order/$2",
  // Required.
  Rules map[string]string

  // RegexRules defines the URL path rewrite rules using regexp.Regexp with captures.
  // Every capture group in the values can be retrieved by index e.g. $1, $2 and so on.
  // Example:
  // "^/old/[0.9]+/":     "/new",
  // "^/api/.+?/(.*)":     "/v2/$1",
  RegexRules map[*regexp.Regexp]string
}

Default configuration:

Name	Value
Skipper	DefaultSkipper

Regex-based rules

For advanced rewriting of paths, rules may also be defined using regular expressions. Normal capture groups can be defined using () and referenced by index ($1, $2, …) in the rewritten path.

RegexRules and normal Rules can be combined.

e.Pre(middleware.RewriteWithConfig(middleware.RewriteConfig{
  Rules: map[string]string{
    "^/v1/*": "/v2/$1",
  },
  RegexRules: map[*regexp.Regexp]string{
    regexp.MustCompile("^/foo/([0-9].*)"):  "/num/$1",
    regexp.MustCompile("^/bar/(.+?)/(.*)"): "/baz/$2/$1",
  },
}))