From 95d3f10bc96358eef717722e7a614a0970b3c8e1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emanuel=20Gu=C3=A9vel?= <guevel.emanuel@gmail.com>
Date: Sun, 20 Apr 2025 16:06:55 +0200
Subject: [PATCH] HtmxMiddleware: add Vary header to prevent caching issues

See https://htmx.org/docs/#caching
---
 src/jetzig/middleware/HtmxMiddleware.zig | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/jetzig/middleware/HtmxMiddleware.zig b/src/jetzig/middleware/HtmxMiddleware.zig
index 26f26fd..06d7ffe 100644
--- a/src/jetzig/middleware/HtmxMiddleware.zig
+++ b/src/jetzig/middleware/HtmxMiddleware.zig
@@ -19,17 +19,21 @@ pub fn afterRequest(request: *jetzig.http.Request) !void {
 
 /// If a redirect was issued during request processing, reset any response data, set response
 /// status to `200 OK` and replace the `Location` header with a `HX-Redirect` header.
+/// Add Vary response header to prevent caching the page without layout for requests not coming
+/// from htmx.
 pub fn beforeResponse(request: *jetzig.http.Request, response: *jetzig.http.Response) !void {
-    switch (response.status_code) {
-        .moved_permanently, .found => {},
-        else => return,
-    }
-
     if (request.headers.get("HX-Request") == null) return;
 
-    if (response.headers.get("Location")) |location| {
-        response.status_code = .ok;
-        request.response_data.reset();
-        try response.headers.append("HX-Redirect", location);
+    switch (response.status_code) {
+        .moved_permanently, .found => {
+            if (response.headers.get("Location")) |location| {
+                response.status_code = .ok;
+                request.response_data.reset();
+                try response.headers.append("HX-Redirect", location);
+            }
+        },
+        else => {
+            try response.headers.append("Vary", "HX-Request");
+        },
     }
 }