Rewrite Middleware

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.

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 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.

Rewrite middleware should be registered via Echo#Pre() to get triggered before the router.

Custom Configuration

Usage

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

Configuration

// RewriteConfig defines the config for Rewrite middleware.
  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.
    Rules map[string]string `yaml:"rules"`

    // 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.
    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 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{
    Rewrite: map[string]string{
      "^/v1/*": "/v2/$1",
    },
    RegexRewrite: map[*regexp.Regexp]string{
      regexp.MustCompile("^/foo/([0-9].*)"):  "/num/$1",
      regexp.MustCompile("^/bar/(.+?)/(.*)"): "/baz/$2/$1",
    },
  }))