Rewrite | Echo

Rewrite middleware allows to rewrite an URL path based on provided rules. It can be helpful for backward compatibility or just creating cleaner and more descriptive links.

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 asterisk can be retrieved by index e.g. $1, $2 and so on. Each asterisk will be non-greedy (translated to a capture group (.*?)) and if using multiple asterisk a trailing * will match the "rest" of the path.

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.Rexexp 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
}

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

RegexRules and normal Rules can be combined.

  e.Pre(RewriteWithConfig(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",
    },
  }))