Trailing slash middleware with option to redirect

Signed-off-by: Vishal Rana <vr@labstack.com>

middleware/slash.go

@@ -4,17 +4,39 @@ import (
 	"github.com/labstack/echo"
 )
 
+type (
+	// TrailingSlashConfig defines the config for TrailingSlash middleware.
+	TrailingSlashConfig struct {
+		// RedirectCode is the status code used when redirecting the request.
+		// Optional but when provided the request is redirected using this code.
+		RedirectCode int
+	}
+)
+
 // AddTrailingSlash returns a root level (before router) middleware which adds a
 // trailing slash to the request `URL#Path`.
 //
 // Usage `Echo#Pre(AddTrailingSlash())`
 func AddTrailingSlash() echo.MiddlewareFunc {
+	return AddTrailingSlashWithConfig(TrailingSlashConfig{})
+}
+
+// AddTrailingSlashWithConfig returns a AddTrailingSlash middleware from config.
+// See `AddTrailingSlash()`.
+func AddTrailingSlashWithConfig(config TrailingSlashConfig) echo.MiddlewareFunc {
 	return func(next echo.HandlerFunc) echo.HandlerFunc {
 		return func(c echo.Context) error {
-			url := c.Request().URL()
+			rq := c.Request()
+			url := rq.URL()
 			path := url.Path()
 			if path != "/" && path[len(path)-1] != '/' {
-				url.SetPath(path + "/")
+				path += "/"
+				uri := path + "?" + url.QueryString()
+				if config.RedirectCode != 0 {
+					return c.Redirect(config.RedirectCode, uri)
+				}
+				rq.SetURI(uri)
+				url.SetPath(path)
 			}
 			return next(c)
 		}
@@ -26,13 +48,26 @@ func AddTrailingSlash() echo.MiddlewareFunc {
 //
 // Usage `Echo#Pre(RemoveTrailingSlash())`
 func RemoveTrailingSlash() echo.MiddlewareFunc {
+	return RemoveTrailingSlashWithConfig(TrailingSlashConfig{})
+}
+
+// RemoveTrailingSlashWithConfig returns a RemoveTrailingSlash middleware from config.
+// See `RemoveTrailingSlash()`.
+func RemoveTrailingSlashWithConfig(config TrailingSlashConfig) echo.MiddlewareFunc {
 	return func(next echo.HandlerFunc) echo.HandlerFunc {
 		return func(c echo.Context) error {
-			url := c.Request().URL()
+			rq := c.Request()
+			url := rq.URL()
 			path := url.Path()
 			l := len(path) - 1
 			if path != "/" && path[l] == '/' {
-				url.SetPath(path[:l])
+				path = path[:l]
+				uri := path + "?" + url.QueryString()
+				if config.RedirectCode != 0 {
+					return c.Redirect(config.RedirectCode, uri)
+				}
+				rq.SetURI(uri)
+				url.SetPath(path)
 			}
 			return next(c)
 		}