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+++ title = "Rewrite Middleware" description = "Rewrite middleware for Echo" [menu.main] name = "Rewrite" parent = "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",
    },
  }))