Flatten redirect chains using recursive sql query

redirects.go

@@ -10,7 +10,7 @@ import (
 var errRedirectNotFound = errors.New("redirect not found")
 
 func serveRedirect(w http.ResponseWriter, r *http.Request) {
-	redirect, more, err := getRedirect(r.Context(), slashTrimmedPath(r))
+	redirect, err := getRedirect(r.Context(), slashTrimmedPath(r))
 	if err == errRedirectNotFound {
 		serve404(w, r)
 		return
@@ -18,12 +18,6 @@ func serveRedirect(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
-	// Flatten redirects
-	if more {
-		for more == true {
-			redirect, more, _ = getRedirect(r.Context(), trimSlash(redirect))
-		}
-	}
 	// Send redirect
 	w.Header().Set("Location", redirect)
 	render(w, templateRedirect, struct {
@@ -34,17 +28,16 @@ func serveRedirect(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusFound)
 }
 
-func getRedirect(context context.Context, fromPath string) (string, bool, error) {
+func getRedirect(context context.Context, fromPath string) (string, error) {
 	var toPath string
-	var moreRedirects int
-	row := appDb.QueryRowContext(context, "select toPath, (select count(*) from redirects where fromPath=(select toPath from redirects where fromPath=?)) as more from redirects where fromPath=?", fromPath, fromPath)
-	err := row.Scan(&toPath, &moreRedirects)
+	row := appDb.QueryRowContext(context, "with recursive f (i, fp, tp) as (select 1, fromPath, toPath from redirects where fromPath = ? union all select f.i + 1, r.fromPath, r.toPath from redirects as r join f on f.tp = r.fromPath) select tp from f order by i desc limit 1", fromPath)
+	err := row.Scan(&toPath)
 	if err == sql.ErrNoRows {
-		return "", false, errRedirectNotFound
+		return "", errRedirectNotFound
 	} else if err != nil {
-		return "", false, err
+		return "", err
 	}
-	return toPath, moreRedirects > 0, nil
+	return toPath, nil
 }
 
 func allRedirectPaths() ([]string, error) {